Harpoon 4: Modern Tactical Naval Warfare Rulebook

Table of Contents

Table of Contents

• Chapter One – Introduction
  • 1.1 Background
  • 1.2 Limits
  • 1.3 Players
  • 1.4 Scale
  • 1.5 Equipment
  • 1.6 Organization
  • 1.7 Game Counters
• Chapter Two – Game Mechanics
  • 2.1 Game Preparation
  • 2.2 Turn Sequence
  • 2.3 Size Classification
  • 2.4 Movement Planning
  • 2.5 Recording Planning
  • 2.6 Detailed Example: A Border in the Gulf
• Chapter Three – Movement
  • 3.1 Ship Movement
  • 3.2 Submarine Movement
  • 3.3 Aircraft Movement
  • 3.4 Missile Movement
  • 3.5 Torpedo Movement
  • 3.6 Collisions and Ramming
  • 3.7 Units Arriving in the Battle Area
• Chapter Four – Detection
  • 4.1 Detection System Basics
  • 4.2 Radars
  • 4.3 Electronic Support Measures (ESM)
  • 4.4 Sonars
  • 4.5 Visual Observation
  • 4.6 Infrared Detection Systems (Thermal Imagers)
  • 4.7 Magnetic Anomaly Detector (MAD)
  • 4.8 Laser Detection Systems
• Chapter Five – Weapon Characteristics
  • 5.1 Weapon Directors
  • 5.2 Rate of Fire
  • 5.3 SSM, SAM, and ASM Missile Guidance Systems
  • 5.4 AAM Guidance Systems
  • 5.5 Torpedo Guidance Systems
• Chapter Six – Combat
  • 6.1 Firing Solutions
  • 6.2 General Combat Procedures
  • 6.3 Air Attacks
  • 6.4 Surface Ship Attacks
  • 6.5 Submarine Attacks
  • 6.5.3 Submerged-Launch Anti-Ship Missiles
  • 6.6 Directed-Energy (Laser) Weapons
  • 6.7 Electronic Warfare
• Chapter Seven – Combat Results
  • 7.1 General Concept
  • 7.2 Damage
  • 7.3 Critical Hits
  • 7.4 Repairs
  • 7.5 Equipment Availability (optional rule)
• Chapter Eight – Aircraft Availability
  • 8.1 Pilots and Flight Crew
  • 8.2 Aircraft Damage
  • 8.3 Aircraft Maintenance

Chapter One – Introduction

1.1 Background

Harpoon simulates modern naval combat. It covers air, surface, or submarine engagements at a tactical (individual) level. Its description of how naval forces are used allows a player with little or no experience of naval combat to understand the underlying principles of naval warfare and to learn.

Modern naval warfare differs radically from "classic" World War II-style naval warfare. In 1939, at the start of the war, there were two types of naval units, with few offensive options for each. Surface units fired guns or launched torpedoes against other surface units, fired guns against aircraft, and dropped depth charges against submarines. Aircraft dropped bombs or torpedoes against ships, and depth charges against submarines. Submarines torpedoed merchant ships, attacking warships only when they happened to be in the right place at the right time. The only detection devices available were sonar (brand new and overrated), radar (still secret), and visual observation.

Naval warfare 50 years later is completely different. New types of weapons and detection devices have given ships, aircraft, and submarines entirely new capabilities. Helicopters, nuclear propulsion, nuclear weapons, infrared sensors, guided missiles, and many other systems have spread through all naval equipment and multiply the possibilities of detecting and destroying an opponent.

Whereas before, battleships or hundreds of aircraft were needed to win, today a single aircraft, a single missile, or even just a decision can decide victory. The rare modern naval combat engagements have revealed that combat today is more intense than in World War II, concentrating the same violence into a fraction of the time. During World War II, ships sailed in columns and then deployed into combat formation; reaction time was measured in hours. Today's naval units must always be in combat formation, and attacks can be launched only seconds after detection.

As you can imagine, the capabilities of naval weapons have been greatly improved since 1939. Naval gunnery, whose fundamentals remain unchanged, has seen its range and accuracy increased. Torpedoes have longer range, and are faster and more accurate than their World War II ancestors. Radars have increased range, better resolution, and greater reliability. Everything used by combatants during World War II is still used, but with greater power and better efficiency.

As might be expected, entirely new naval capabilities have developed since World War II. Technology has produced new weapons and equipment to meet the needs of modern naval operations. Helicopters give small ships the ability to extend the range of their detection and attack systems. Satellites let commanders detect and target surface ships that no friendly unit has spotted. Missiles make even the smallest ships genuine threats to the largest. Countermeasures make ships and aircraft less detectable by sonar and radar. And as new naval capabilities are added to the inventory, the options (and problems) facing commanders increase.

Technology is the driving force behind these new capabilities, naval warfare being more sensitive to technological change than land warfare. On land, the dominant force remains the infantry; technology has not changed that much. At sea, on the other hand, the development of a new weapon or detection device can have dramatic effects. Naval warfare consists of machines fighting other machines, directed and crewed by men who are part of them and who handle what the machines cannot do. Since naval warfare became mechanized, the goal has been to take man out of the "loop" to maximize speed and efficiency. Automatic guns on mounts are one example, as are automated propulsion systems and combat systems. Not only are men removed from dangerous and difficult tasks, but response time is reduced along with the manpower needed aboard. The Aegis system is the perfect example: it detects, identifies, and engages hostile air targets without human intervention (though under human direction). Technological advances make such a system possible, but they also increase the burden on the man ultimately responsible, the ship's commander. He must interpret the information presented to him, since Aegis cannot give the commander everything he needs to know.

What does this mean for a naval wargame? Technology is complex and costly, with many small details and limitations that can put off a player. A game should give players only meaningful detail and ignore the rest. Some details simply are not important to the player at his level of control. The commander of a ship or formation is not interested in an aircraft's maintenance log, or the exact frequency of its sonars; his subordinate officers handle that, leaving him the view of the whole picture.

Harpoon keeps detail at the appropriate level, so that the player takes on the role of a ship's commander. The game assumes that guns fire the appropriate ammunition and that the target is in range. If that is not the case, the gun does not fire. The player must concentrate on tactical decisions. Should he order two ships to detach from the formation to reconnoiter? Or should he keep them in formation to increase its defensive strength? The player, as ship or formation commander, gives orders such as "engage that target with your guns," or "send a two-ship group to see if the enemy force is in that direction." The role of a formation commander is to end hesitation and decide, sometimes on the basis of errors or incomplete information, on the best course of action.

Harpoon gives the player the same decision-making power as a battle group commander fighting in a modern naval engagement. It gives him the information available to the commander for making decisions. More than that, it lets the player make his decisions and see their results in a combat simulation.

All this means that Harpoon resembles a serious simulation, but all wargames strive toward that goal. We just want Harpoon players to understand that they can use the game not only to fight each other in a structured way, but also to understand what happens on the world's oceans. It can be used to recreate naval engagements such as the Falklands or the Persian Gulf, or to explore confrontations that never took place.

Although we consider Harpoon a game, it was not designed with balanced play in mind; it is closer to a simulation. The data reflect real weapons and equipment from around the world, used within a game system that lets them interact. Tactics ordinarily used in the real world work in this simulation. We cannot say whether a player will have better than 50% odds of beating the other; that depends on who has the initiative and on the players' skill.

Every player will learn naval tactics by playing Harpoon. He will learn the relative value of naval units and how they can act together. He will be able to reproduce recent naval engagements and examine what forces were present, or try hypothetical units purely on the game board to see if they were worthwhile. Over a longer period, he will be able to appreciate how a country's naval forces serve its national interests.

But no player has to understand modern naval warfare to begin playing Harpoon. With each game, and with experience, an understanding of naval warfare will come naturally.

These rules assume an understanding of basic terms (whose definitions are available in the dictionary) such as cruiser, destroyer, sonar, or radar. Anything beyond these basics is explained in the appropriate section of the rules. Annex P contains a list of abbreviations used in the rules.

When a player has gained experience with Harpoon, and has read books on the subject, he will discover that the rule is too simple. Then change the rule. We had to radically simplify certain aspects of naval warfare in order to both increase playability and make the game easy to learn. Harpoon has a modular architecture that allows chapters of the rules to be changed or added with minimal effort. New weapon systems can also easily be added.

Units are expressed in real-world units of measure: knots, meters, kilograms, degrees. We were forced to use damage points to quantify a ship's ability to withstand damage, but the formulas for converting any ship to this system appear in Annex Q. It also contains the usual values for metric conversion and for converting the game to different scales.

In designing Harpoon, we made a number of assumptions about how units could interact in order to produce what we consider a realistic result. These assumptions form the game's guiding thread and strongly influence how it should be played.

1. The hardest part of naval warfare is finding and targeting the opponent's position. As during World War II, and even more so today. The proliferation of detectors has not changed the detection process much.

2. A modern ship is relatively easy to destroy. During World War II, a ship could absorb several hits or explosions before its effectiveness was diminished. A modern ship has many fragile systems that can be damaged and is far less armored. Modern weapons also have greater explosive power, mass for mass. As a result, a single hit will most often inflict enough damage to put a ship out of action (a "mission kill").

3. Today's reactions must be faster than during World War II. World War II naval wargames use turns of 3 to 6 minutes. That represents the time it takes commanders to understand what is happening, then to give orders based on the information they have gathered (the decision cycle). Because of the speed of most threats, ships must react faster, which translates into 30-second engagement turns. This makes the high-speed tactical maneuvering of a ship more important than during World War II. When a missile is moving at 600 knots while a ship is moving at 30 knots, the ship's relative displacement is insignificant, except as it relates to turning to bring its weapons to bear.

Finally, all information used in this game comes from unclassified government, civilian, or military sources listed in the bibliography. We simply gathered information from many different sources, compared them, and tried to resolve differences by making the best use of them and translating them into common values. We have also indicated the books or publications we recommend as good summaries and useful background that every good naval wargamer should have in his library.

The information available in this game is as accurate and current as possible, but some data, such as hit probabilities and exact weapon ranges, may vary from source to source. However, certain prestigious works such as Combat Fleets of the World and Jane's Fighting Ships can prove to be good sources regarding weapon or sensor performance. Data on the physical characteristics of aircraft or missiles is easy to find. Performance information is suspect in every case because it is based on test firings conducted under ideal conditions. There is little information gathered under combat conditions to judge by. Modern game designers must accept that the systems they describe are being used for the first time, and that only a minority will perform at their best. A majority will perform with limited effectiveness, and another minority will fail. There is no way to predict what will work.

Naming Ships. Most warships of at least corvette size are named after a person, a place, an event, an animal, or even a plant or mineral. The procedure for giving a ship a name is called christening ("commissioning") and is equivalent to a baptism for a newborn. The ceremony, steeped in tradition, marks the "birth" of the ship.

A commonly made mistake when referring to a ship is to say "the USS Iwo Jima." This is equivalent to calling one of your friends "the Jeff" or "the Marie." A ship's name, and the way it is used, should reflect that fact. It can be useful to remember that a prefix such as USS or HMS is the equivalent of "Mr." preceding a name, or a very suitable formal way of referring to it. Although many sources, including the Navy's own, put the name before important terms, even within an article, this formulation is incorrect.

Once past this first hurdle, a ship's name must be written in italics. The ship's name, Iwo Jima, must be written in italics.

Some ship classes are named after the first ship of the class, for example the Spruance class. Other classes may be designated after a category, such as the British "County" or "Duke" classes. These class names are not written in italics, because they are not carried by any single ship.

Likewise, Russian and Chinese ship names are not written in italics. In other words, Petropavlosk is a Kara-class unit. Some people prefer to write "KARA" in capital letters, but this makes the text too bulky.

Some ships that have entered service ("been commissioned") have no name. We know that most Russian submarines are designated by the random number appearing on their hull. As these ships are in service, the number appearing on their hull is their name and must therefore be written in italics. For example, the Russian Typhoon class (NATO code name) includes the units TK-208 and TK-12.

We know the names of most Soviet/Russian equipment, but their NATO designation is more widespread. We apply the following convention: if we use the Russian name of the equipment, we will immediately follow it with its NATO designation in brackets. For example, we may refer to the Project 971 Bars class of submarines [Akula]. NATO designations will appear in brackets only for Russian names.

1.2 Limits

Harpoon's rules simulate surface, subsurface, or air attacks against naval units, aircraft, and certain land units. They cover surface gunnery, cruise missiles, SAMs, and electronic and anti-submarine warfare.

The annexes provide the characteristics of Belgian, Canadian, French, German, Iranian, Israeli, Italian, Indian, Dutch, Norwegian, Portuguese, Swedish, Russian, British, American, and Yugoslav ships. Ships of other nations will be covered by future supplements, or may be incorporated into play using Annex Q.

The rules do not cover amphibious assaults, mine warfare, towing, or clandestine resupply, because the time required for these evolutions or these tactical doctrines does not involve naval combat.

1.3 Players

Harpoon requires two players — one for each side of the scenario. Harpoon plays best, however, with three, with a referee.

In Harpoon, a referee is in charge of the entire game; he sets up the scenario and distributes information to the players before and during the game. The referee observes everything that happens during the scenario. He interprets and enforces the rules. He determines which side can make detections, and reveals which side is detected. When the scenario is over, he can comment on the actions of both sides, explaining to them what happened, what could have happened, and what the best solutions were.

1.4 Scale

Harpoon uses several scales to compress distance and time, making them manageable.

1.4.1 Turns. Three types of turns are used. The intermediate turn represents 30 minutes. The tactical turn represents 3 minutes. The engagement turn lasts 30 seconds.

1.4.2 Distance. Distance is measured in nautical miles, the standard unit of distance at sea. A nautical mile equals 2,000 yards or 6,000 feet, just a bit less than the 5,280 feet of a standard mile. Harpoon uses a variable distance scale, but the typical scale is one inch to one nautical mile, or one inch to two nautical miles. Since distances are expressed in miles, other scales are possible: 10 inches to one nautical mile for close-in ASW actions, or one inch to 5 nautical miles for long-range air battles.

1.4.3 Altitude. Altitude above sea level is measured in meters.

1.4.4 Depth. Depth is expressed in terms of depth levels, as explained in Chapter 3.

1.4.5 Speed. Speeds are given in knots (nautical miles per hour). A ship's or aircraft's speed in knots divided by two gives that unit's movement distance during a 30-minute intermediate turn. Speed in knots divided by 20 gives the distance covered in a 3-minute tactical turn. Speed divided by 240 gives the distance covered during the movement phase of an engagement turn (15 seconds). There are two movement phases in an engagement turn.

1.5 Equipment

This Harpoon box contains the following components:

1 rulebook, 1 scenario book 1 data annex book, 2 counter sheets 2 ten-sided dice, 2 six-sided dice

In addition, the following equipment is required:

Copies of the ship, aircraft, and submarine reference sheets, tactical orders sheets, air operations sheets, air mission planning sheets, and formation sheets. These are supplied at the back of the scenario book.

A flat playing area of approximately 120 cm by 240 cm. A larger playing area can be useful. The game does not require a hex-covered map.

A measuring system. Distances are measured deck-to-deck from one ship to another.

A protractor.

Graph paper. Submarine movements are logged on graph paper.

A pocket calculator is strongly recommended, but not essential.

Pencils and pens.

Dice. The minimum required is 2 ten-sided dice (D10) and 2 six-sided dice (D6). They are supplied with the game. More dice allow for faster, smoother play.

Miniature ships (or counters) representing the units required by the scenario. If the ships used in the scenario are not included in the box, counters must be made to represent them, although all ships referenced by the quick-start booklet are included on the counter sheet.

1.6 Organization

Harpoon is organized into two books and a booklet. The rulebook describes the game's concepts and rules. The Data Annex Book contains detailed information on a number of ships, aircraft, weapons, and sensors. The quick-start booklet summarizes the rules and provides an introduction to the game's scenarios.

Players will learn the system and naval tactics by playing the scenarios. Additional scenarios will become available soon in future publications.

The rulebook also contains blank versions of the game's reference sheets. These are photocopiable; they should remain unmarked so they can serve as a source of additional copies. Players are permitted to photocopy them without restriction.

1.7 Game Counters

This game includes a set of pre-cut cardboard ships and aircraft, which are an alternative to metal or plastic miniatures. Other markers represent missiles in flight or locations on the playing surface.

Miniature ships in 1/2400 or 1/3000 scale are perfect for Harpoon. Aircraft may be represented by miniatures or cardboard counters. Miniature submarines are not usually necessary. Missiles are ideally represented by cardboard counters.

Other ship scales are also possible. Annex Q provides information for converting Harpoon to 1/1200. It is also possible to play Harpoon directly on paper or a map, dispensing with counter representation of units.

Chapter Two – Game Mechanics

Harpoon simulates reality. The rules aim, within certain limits, to describe how naval warfare works in the real world. They encourage players to use tactics that can be used in real naval warfare. Because the game aims to be realistic, common sense is a valuable asset in Harpoon. Rules or interpretations that seem unreasonable may be changed or ignored. The game should feel real to the players.

Scenarios may be run by a referee (an independent person who applies the rules and gives information to each side), or by the players themselves.

2.1 Game Preparation

Once a scenario has been chosen, players need a Ship Reference Sheet for each of their ships and an Air Data Card for each aircraft or group of aircraft. The ships and aircraft used are those mentioned in the scenario. The masters of the Ship Reference Sheets and Air Data Cards may be photocopied without restriction.

Using the scenario's information, players prepare the Ship Reference Sheets and Air Data Cards by copying onto them the data provided in the Data Annex Book. These sheets then contain all the information each player needs to use his ships and aircraft during the scenario.

2.1.1 Filling Out the Ship Reference Sheets. Make a copy of the Ship Reference Sheet for each ship or submarine involved in the scenario being played. You can use the information available in Annex A to fill out the sheets. Transferring this data to the sheet will let you play faster without having to flip through book pages once the game has begun.

2.1.1.1 Annex A. Consult Annex A (in the Data Annex Book) and find the data for a scenario ship under its nationality and name. The listing gives general information on all ships of that class. Exceptions applicable to particular ships of the class are listed in the remarks.

2.1.1.2 Basic Data. The first part of the ship listing provides basic statistics and performance data. Fill in on the Ship Reference Sheet (items 1 through 9) the ship's name, class, type, displacement (in tons), speed (in knots), propulsion system, crew, mounted weapons, and the number of embarked aircraft.

A mounted weapon is defined as a weapon installed on a ship. This can be a single 20mm gun or an auto-reloading ASW rocket launcher, or a multi-cell vertical missile launch system. Many warships have several mounted weapons of different types.

2.1.1.3 Damage and Speed Loss. Transfer to the Ship Reference Sheet the damage and post-damage speeds from Annex A based on the appropriate references. If the vessel is a surface ship, disregard the line for submerged speeds on the Ship Reference Sheet.

Damage points, in Harpoon, measure the damage inflicted on a ship. Different weapons inflict different damage points. Ships can absorb such damage depending on their displacement, type, and construction. Annex Q provides a complete procedure for calculating the number of damage points a ship can absorb.

Special characteristics, provided for under the ship-construction rules, such as the use of unusual materials, allow a ship's damage-point level to be increased or decreased. For reference, these damage modifiers are noted in the ship remarks in Annex A, but are always already factored into the damage-point values.

2.1.1.4 Radars. Find the sensors section in the ship listing and transfer the name of each detector marked J (in the right-hand margin) to the radar section of the Ship Reference Sheet. Then go to Annex J to find each type of radar and transfer its statistics to the appropriate line of the Ship Reference Sheet.

2.1.1.5 Sonars. Return to the sensors section of the ship listing and transfer the name of each detector marked M (in the right-hand margin) to the sonar section of the Ship Reference Sheet. Then go to Annex M to find each type of sonar and transfer its statistics to the appropriate line of the Ship Reference Sheet.

2.1.1.6 Weapons. Find the weapons section of the ship listing and read each weapon line, noting its annex letter (marked to the right of each line).

Weapons are listed one per line, and give the firing arc, the number of barrels/rails/tubes per mount, the number of mounts on the ship, the weapon's name, the type of ammunition available per weapon carried, the rate of fire, and the presence of any fire-control director. The sample weapon data line below illustrates this format.

Copy the weapon's name into the appropriate section of the Ship Reference Sheet. Then go to Annex C (for guns), D (for missiles), E (for anti-submarine warfare systems — ASW), or F (for torpedoes), find each weapon, and transfer its statistics to the appropriate line of the Ship Reference Sheet. The missile's name can sometimes be found in place of the mounted weapon's name (e.g. Sea Wolf) or as ammunition (e.g. the Mk26 launcher can fire SM1MR or SM2MR missiles).

Sample weapon data line:

F (8) 1 Mk29 NATO SSparrow w/8 RIM-7M//1 MK91 (15) D

Reading, left to right: the annex letter where the weapon's data can be found; the firing arc (this single mount is oriented aft, with a blind arc forward); the number of tubes per mount (eight, in this case); the number of mounts of this type on the ship; the launcher's name; the rate of fire in rounds per engagement turn; the type of fire-control director radar; the number of director radars; the name of the ammunition type; and the number of rounds/salvos carried.

2.1.1.7 Remarks. Find the remarks section of the ship listing and read the information there carefully. Note anything specific to the ship and transfer it to the remarks section of the Ship Reference Sheet. Pay particular attention to important modifications and special features of weapons and detectors, general and critical armor, magazine capacities, and special rates of fire.

2.1.1.8 Weapon Firing Arcs. Every mounted weapon has a firing arc. A weapon mounted forward cannot fire aft because the ship's structure blocks its line of fire. Some weapons, such as large missile launchers, may not be able to train, and their arc is then limited by the weapon's ability to pivot once launched. The arc of each mounted weapon is specified in Annex A of the ship listing. If a target is not within a weapon's firing arc, that weapon cannot fire at it.

All arcs mentioned in Harpoon are shown on the shipboard weapon firing arcs diagram: Port Bow (PB), Starboard Bow (SB), Port Quarter (PQ), Starboard Quarter (SQ), Portside (P), Starboard Side (S), Forward (F), Aft (A), Port Aft (PA), Starboard Aft (SA), Port Wing (PW), and Starboard Wing (SW), each covering a defined arc measured from the bow or stern, with 30° cutouts fore and aft as shown. Each arc has an abbreviation which is given on the weapon's line. For example, "F" designates a weapon aimed forward, which has a blind zone aft.

A slash (/) designates the arcs of several mounts: P/S(1)2 indicates that there are two single mounts, one oriented to port and one oriented to starboard.

Some weapons can fire into more than one arc. The ampersand (&) combines arcs: P&PQ/S&SQ(1)2 indicates that there are two mounts with a single barrel each, one oriented to fire on both the port arc and the port quarter, and the other oriented to fire on both the starboard arc and the starboard quarter.

The parentheses contain the number of tubes, barrels, or rails each mount has.

2.1.1.9 Examples. Sample Ship Reference Sheets for an O.H. Perry-class frigate and an Iranian Houdong-class missile boat appear on pages 2-4 and 2-5. They are used in the detailed example in section 2.6.

2.1.2 Filling Out the Air Data Card. Make a copy of the Air Data Card for each group of 4 aircraft or fewer of the same type. Generally, each aircraft or helicopter operating alone should have its own card; aircraft operating together may share a single card.

2.1.2.1 Annex B. Take Annex B (in the Data Annex Book) and find the scenario's aircraft in the aircraft listing under its nationality and name. The listing gives general information on the aircraft. Exceptions and variants are listed in the remarks.

2.1.2.2 Basic Data. The first part of the aircraft listing provides basic statistics and performance data. Fill in on the Air Data Card (items 1 through 5) the aircraft type, mission, ceiling, ATA (air-to-air index), and D-ATA (air-to-air defense index).

2.1.2.3 Speed and Altitude. Transfer the speed and altitude values from Annex B to the appropriate sections of the Air Data Card. The value in brackets after the speed represents the distance in nautical miles per 15-second movement phase at that speed. For example, a speed of 240 knots should be written "240(1.0)".

2.1.2.4 Radar. Find the "sensors" section of the aircraft listing and transfer the name of each radar to the radar section of the Air Data Card. Then refer to Annex L, find each radar type, and transfer its statistics to the appropriate line of the Air Data Card.

2.1.2.5 Sonar. Return to the "sensors" section of the aircraft listing and transfer the name of each sonar or sonobuoy to the appropriate section of the Air Data Card. Then refer to Annex M1, find each sonar type, and transfer its statistics to the appropriate line of the Air Data Card. Consult Annex M2 for the aircraft's ASW systems.

2.1.2.6 Other Detectors. Return once more to the "sensors" section of the aircraft listing and transfer the name of each other detector to the detectors section of the Air Data Card. Then refer to the Data Annex Book, find each one, and transfer its statistics to the appropriate line of the Air Data Card. These detectors include:

• Radar — Annex J
• Sonar — Annex M
• FLIR — sections 4.6 and 4.6.2
• MAD — section 4.7
• ESM — section 4.3
• RWR — section 4.3
• LRMTS — section 4.8.3

2.1.2.7 Offensive Load. Find the weapons section of the aircraft listing and select a type of offensive load from that section. Note the name of each weapon in the offensive load and transfer the data to the appropriate section of the Air Data Card. Then refer to Annexes G or H, find the weapon, and transfer its statistics to the appropriate line of the Air Data Card.

2.1.2.8 Remarks. Find the remarks section of the aircraft listing and read the information given there carefully. Note any information applying to the aircraft and transfer these observations to the remarks section of the Air Data Card.

2.1.2.9 Aircraft Group. The Air Data Card can represent up to 4 aircraft of the same type operating together. In the remarks section of the Air Data Card, write one to four separate identification numbers to indicate the aircraft represented. These numbers will be used to identify the individual aircraft when orders are given or targets identified. As aircraft are destroyed, these numbers are crossed out.

2.2 Turn Sequence

Harpoon is played in turns. As long as there is a chance the two sides will detect each other, players may use 30-minute intermediate turns. This lets ships move long distances when there is no need to react or make a decision. Naval warfare consists of hours of boredom while both sides search for each other or move. The intermediate turn compresses time, speeding up the game and letting both sides play faster in real time.

While moving during intermediate turns, both sides should be executing a battle plan prepared before the game began. The plan can be modified if enemy units are detected or if some other change occurs, but having a plan at the start of the game speeds things up. This also reflects the tasks of real-life commanders.

Once enemies are detected, switch to 3-minute tactical turns.

If high-velocity units (missiles, aircraft) begin interacting with other units, the time scale drops to 30-second engagement turns. This gives players a chance to react to sudden threats and reflects the reaction speed of modern weapon systems.

The procedure is the same for all turns. The difference lies in the distance traveled. All players do the same thing (detailed by phase) at the same time. Players plan their actions at the same time; they reveal their orders and move their ships at the same time; they open fire at the same time. The rules allow only actions that could reasonably take place given the length of the turn.

2.2.1 Representing Time. Turns can be tracked in real-time units. For example, the first intermediate turn of a scenario might start at 0100 (01:00 on a 24-hour clock). The next turn will begin 30 minutes later at 0130, the next at 0200, and so on.

If two units enter each other's detection zones during the 0130 intermediate turn, movement slows down: the first tactical turn begins at 0130, the second at 0133, and so on. If the action slows back down after the 0130 intermediate turn, the first tactical turn begins at 0200, the next at 0203, and so on.

If the action moves to the 30-second engagement turn, these are noted with decimals. The next turn will begin at 0206.0, the next at 0206.5 (half a minute), the next at 0207.0, and so on.

2.2.2 Intermediate Turn Sequence. Intermediate turns last 30 minutes. No combat is allowed; only movement and detection are.

Unless the scenario begins with direct contact (i.e., within mutual detection ranges), the game begins with intermediate turns. If, at the end of any detection phase of an intermediate turn, a unit finds itself within detection range of another, the action is stopped. The units then revert to their starting positions from the beginning of the last intermediate turn. Then the action resumes in tactical turns, to allow for detection.

A player may request to switch to tactical turns or engagement turns at any point during an intermediate turn. This reflects the fact that, during a 30-minute turn, a player can react within 30 seconds — the length of an engagement turn — to a threat or a change in the situation. See section 2.2.5 on transitioning to shorter turns.

The game can alternate between intermediate and tactical turns. For example, if the submarine from section 2.2.5 comes within detection range, time shifts to tactical turns. It detects the enemy force and carries out a few actions, changing its depth and speed. The other side has not detected the submarine and will not be able to unless it closes the distance. The submarine may then decide to revert to intermediate turns with an order stating that if it loses contact, it reserves the option of returning to tactical turns to react.

This option is especially useful when there is a referee, when the other side does not know it has been detected. If there are several groups of units moving independently, only those with an interest in maintaining contact switch to tactical turns, while the others continue to move in 30-minute segments.

Players must carry out the following steps at each intermediate turn:

• Planning Phase. Players write their movement orders and other orders. Orders may be expressed as simple movements or as movements subject to specific time or encounter conditions. For example, a player may order Submarine 1 from the diagram on p. 2-8 to close on unit R4 at 30 knots to within 60 nm. This will take it less than a 30-minute intermediate turn to reach the objective; it will not go beyond that but will stop at the appropriate point. The player may then want to switch to tactical or engagement turns at that time, or continue moving in intermediate turns.
• Movement Phase. Units move a distance equivalent to 30 minutes of movement; aircraft may take off or land. Some units may not move for the full 30 minutes. For example, if a helicopter is on 5-minute alert and ordered to take off at the start of an intermediate turn, it will take off and move a distance equal to 25 minutes of flight. Conversely, if in an intermediate turn the player orders it to take off next turn, it will then fly for the full 30 minutes.
• Detection Phase. Players check their units' detectors to determine which are relevant and see whether they are within detection range of a hostile unit. If so, players must switch to tactical turns.

2.2.3 Tactical Turn Sequence. The tactical turn lasts 3 minutes. Air units may use this turn type if they are not interacting with other units. Torpedo combat and long-range missile combat are allowed. The following phases are carried out simultaneously by the players in each tactical turn.

• Planning Phase. Players write their movement orders, plan their fire, and so on. Orders may be expressed as simple movements or as movements subject to specific time or encounter conditions. Players may plan their fire for the next planned-fire phase only against targets detected during the previous detection phase.
• Movement Phase. Units move a distance equivalent to 3 minutes of movement. Aircraft may take off or land. Missiles and torpedoes that reach their target during this phase are resolved, and if they hit their target, damage is inflicted during this phase.
• Planned Fire Phase. All weapons that received a fire order during the planning phase fire simultaneously. Gun, ASW mortar, and depth-charge attacks in this phase are resolved immediately.

Missiles may be launched in this phase, but will not be able to move until the movement phase of the next tactical turn.

The Three-Minute Rule. During tactical-turn movement, the following shortcut can be used: take a unit's speed in knots and add two zeroes. This represents the distance traveled in yards in 3 minutes. E.g., a destroyer moving at 15 knots travels 1,500 yards in 3 minutes.

Firing guns or launching missiles can change a unit's signature (its detectability). This change takes effect immediately and affects its chances of being detected during the next detection phase.

• Detection Phase. Players exchange visual, radar, sonar, etc. information. Units attempt to detect ships, missiles, and aircraft. A unit can only react once the threat has been detected, even if the active player is aware of it.
• Reaction Fire Phase. All onboard weapons not yet used may fire on any newly detected threat or on targets already located.

Surface-to-surface missiles and non-homing torpedoes, which require preparation time before launch, cannot be launched during a tactical turn's reaction fire phase. If a player needs to launch surface-to-air missiles during a reaction fire phase, he must choose to switch to engagement turns (see 2.2.5 Transitioning to Shorter Turns).

Homing torpedoes launched during the reaction fire phase also cannot move until the turn's next movement phase. Because they are launched late, the rate of fire is halved. For example, a submarine that normally fires 4 torpedoes per tactical turn can only fire 2.

Autonomous weapons, which are subject to special rules for firing during 30-second engagement turns, are used normally during 3-minute tactical turns. If an autonomous weapon's reaction time is important to resolving the action, players may switch to engagement turns.

ASW mortar and depth-charge attacks are resolved immediately.

2.2.4 Engagement Turn Sequence. Engagement turns last 30 seconds. They are used to resolve movement and combat involving high-speed air units, or situations requiring detailed movement resolution. As soon as a missile or high-speed air unit comes within detection or firing range of an enemy ship, players must switch to engagement turns.

Each engagement turn consists of the following phases:

• First Movement
• First Fire
• Air Attack Resolution
• Detection
• Second Movement
• Second Fire
• Air Attack Resolution

There are 2 fire phases and 2 movement phases in an engagement turn, so at each movement phase, players move their air units the distance they cover in 15 seconds. Slower units, such as ships, helicopters, or torpedoes, may be moved the full 30 seconds' worth at the start of the engagement turn. If they are not directly involved in the action with the high-speed air units, the slower units may be moved a full 3 minutes' worth without a problem. (One key to speeding up the game is to minimize the number of times a player has to handle each unit, ship, aircraft, or missile.)

After each movement phase, a unit may open fire if able to do so. Most naval weapons can only open fire in the first fire phase, e.g. guns, missiles, etc. Their fire may be delayed to the second phase, but their movement will then be halved (missiles, torpedoes, etc.) or their damage halved (guns). Aircraft and autonomous weapons may fire in both phases. All other naval weapons may only fire once.

Weapons launched in a fire phase of an engagement turn will move for the first time in the following movement phase.

After all weapons fire, ship attacks by air units are resolved. Missile attacks against aircraft are resolved during the movement phase, when they reach their intended targets, but anti-ship missiles and high-speed aircraft may move so fast that a ship's short-range defensive weapons will have no chance of reaching them. For this reason, fast-moving attacking missiles or aircraft are frozen when they reach their target until all of the target's defensive weapons have opened fire.

Before the second movement phase, players have a detection phase, to give them a chance to detect new units.

2.2.5 Transitioning to Shorter Turns. A modern naval battle is very short. The May 1982 attack on HMS Sheffield, from missile launch to impact, took less than 3 minutes. During a fast-moving naval battle, many decisions must be made very quickly. If a commander lets the situation drift, even for a brief moment, he may find himself overtaken and unable to catch up.

Players may invoke a switch to shorter turns at any time, but they must request it during the planning phase or the detection phase of an intermediate or tactical turn.

If a player invokes a tactical turn during an intermediate turn, the next tactical turn will begin at the planning phase.

If a player invokes an engagement turn during a turn's planning phase, the next engagement turn will begin at the first movement phase. If it is invoked during the detection phase of a tactical turn, then the following engagement turn will begin at the second fire phase.

Example: A game begins at 1200. The players move in 30-minute Intermediate Turns, at 1230, 1300, and 1330. During the detection phase of the 1330 turn, one player's submarine has closed on an enemy group and needs to begin its approach. If the movement of the 1300 Intermediate Turn brought them too close together, it can be cancelled so that they return to their positions from the start of the 1300 turn. Otherwise, if the opponents are not too close, Tactical Turns can be invoked at the end of the turn, using the 1330 positions. We will assume this option was chosen.

The next Tactical Turn will run from 1330 to 1333. The players execute Tactical Turns 1330, 1333, 1336, 1339, 1342, and 1345. During the 1345 turn, the submarine fires a salvo of submerged-launch anti-ship missiles. The moment they leave the water, the other player visually and by radar detects the launch and asks to switch to Engagement Turns. This allows fire in the second fire phase of Engagement Turn 1348.0 (turn 1345 runs until 1348, and the movement for turn 1345 has already taken place). The Engagement Turns will each last 30 seconds.

2.2.6 Transitioning to Longer Turns. Once the need for rapid interaction has passed, players can speed up by moving from engagement turns to tactical turns until they resynchronize with intermediate turns.

Example: In the previous battle, the submarine opened fire during Engagement Turn 1348.0. The combat lasted 8 turns: 1348.0, 1348.5, 1349.0, 1349.5, 1350.0, 1350.5, 1351.0, 1351.5. Since the next tactical turn does not begin until 1354, the players can skip through turns 1352.0, 1352.5, 1353.0, 1353.5 by moving 4 movements at once and returning to tactical turns.

Turn Sequence Summary

Intermediate (30 minutes)	Tactical (3 minutes)	Engagement (30 seconds)
Planning	Planning	First Movement
Movement	Movement	First Fire
Detection	Planned Fire	Air Attack Resolution
	Detection	Detection
	Reaction Fire	Second Movement
		Second Fire
		Air Attack Resolution

2.2.7 Variation in Turn Sequences. Although the phases are presented fairly rigidly, they still have a degree of flexibility. If aircraft do not need to interact with other aircraft or missiles, they can move for 30 seconds in the first movement phase and skip the second.

When a missile reaches a target that cannot defend itself, impact and damage can be resolved immediately (i.e., during the movement phase). Otherwise, the attack must be delayed until the resolution phase. Immediate resolution keeps the playing surface clean, and the fewer the phases, the faster the game moves.

2.3 Size Classification

Several rules covering movement, detection, and combat depend on a unit's size. Aircraft and ships use the same size classification, based on the unit's radar cross-section (RCS).

Size Classification Table

	Ship RCS (m²)	Ship Displacement	Aircraft RCS (m²)	Aircraft Example
Large	1,000,000+	18,000+	100	Backfire
Medium	100,000	5,501–18,000	20	S-3 Viking
Small	10,000	351–5,500	5	F-15, B-1B
Very Small	1,000	21–350	0.1	F-18E, Rafale
Stealth	100	20 or less	0.01	B-2, F-117

Even though there is apparently a large size difference between a big ship and a big aircraft, RCS depends on the frequency and pulse characteristics specific to the radars used. To an air-search radar, a B-52 appears as large as an aircraft carrier does to a surface-search radar. More importantly, the maximum detection ranges for air and surface radars are based on the signatures of the largest units.

Note that size-class ratios are based on a ship unmodified by damage points. Some ships have modifiers based on their nationality, the materials used in their construction, or other special features. For example, a Spruance-class destroyer displaces 6,156 tons and would normally be able to absorb 199 damage points, but because it is built of aluminum, it can only withstand 169 damage points (a damage modifier of -15%). The Spruance's size value given in Annex A is based on the 199-point value.

2.4 Movement Planning

Players move and act simultaneously during the various phases of a turn. Many of these actions must be secretly planned before the phase occurs. Planning consists of thinking through, then writing down, the actions that ships and aircraft will carry out during a turn.

In Harpoon, players record the movements of their surface ships, submarines, and aircraft during the planning phase of each turn (intermediate or tactical). At the same time, they plan their fire, order aircraft to take off or land, and control the execution of their ships' activities. Planning is required for the movement of submarines, ships, aircraft, and any other human-controlled platform.

2.4.1 Elements. Planning a surface ship's movement requires two elements: heading and speed. Planning aircraft movement also includes altitude changes. Planning submarine movement includes depth changes. A unit's speed for the turn is expressed in knots or as distance per turn or phase. Course, or a change of heading, is expressed in degrees.

In standard naval terminology, North is 000°, East is 090°, South is 180°, and West is 270°. North is always true North (at the North Pole), as opposed to magnetic North, the two being distinct. Heading may be abbreviated as, e.g., 090°T, meaning zero-nine-zero degrees relative to true (geographic) North. The compass gives cardinal directions and their degree equivalents.

A protractor is very useful for pinning down the exact number of degrees of a turn. The playing surface should have a clearly marked North so that players are aware of their heading.

An aircraft's altitude change (climb or descent) is expressed in meters. If the aircraft climbs or descends to a new altitude level, its arrival at the new level must be noted. A submarine's depth change is treated as an order to move to a new level and as arrival at that new level.

2.4.2 Secret Submarine Movement. Submarine counters are placed on the playing surface only once they have been detected. In order to better track their movement, each submarine's starting position should be recorded relative to a few standard reference points on the playing surface. For example, a submarine should record its starting position as 26 inches along bearing 300° from the compass rose located on the playing surface.

Submarine movements may be plotted on graph paper at the most convenient scale. The positions of the opposing players' ships should also be marked on the same sheet. The submarine player observes the sonar detection rolls and informs his opponents when the submarine has been detected.

2.4.3 Missiles and Torpedoes. Planning is not required for missiles in flight and torpedoes in motion. They move automatically at their cruising speed toward the target assigned to them at launch.

Variations in course or altitude may occur due to the weapon's guidance system and the control the player exercises over its movement. A change of target may occur if the weapon's guidance system allows it. A change of target is noted on the log sheet.

2.5 Recording Planning

Planning is recorded on the Log Sheet (or any other equivalent sheet of paper). The Log Sheet provided in this book is an example of an acceptable format. The Log Sheet is used to accurately record each player's declared intentions during the turn.

Any Log Sheet can be used in two ways: one sheet for all orders, or one sheet per unit. When a single sheet is used for all orders, players note each unit and its sequence of orders on a single sheet. Additional sheets may be used to fill out the scenario.

When one sheet is used per unit, the player prepares a Log Sheet for each ship, aircraft, and submarine and records orders for each of them on its own sheet.

The Log Sheet has 6 columns: turn, unit, movement, targeting, fire, and remarks.

The turn column is used to record the time the order is given.

The unit column is used to record the precise type of ship or aircraft carrying out the action.

The movement column is used to record speed, direction, and depth/altitude.

The targeting column is used to record weapon guidance systems, fire-control status, and the presence of radar contacts.

The fire column is used to record orders to open fire on targets.

The remarks column is used to record activities not covered by the other columns.

Example of Secret Submarine Movement. This is simply a basic planning example, showing the type of information that needs to be recorded. Players may choose the scale to apply to the playing surface, though they may need to change scale during the game. Graph paper with 10 divisions per inch is most convenient. Planning can use the Log Sheet to keep track of the submarine's position, the status of its weapons and detectors, target information, and its damage level.

Situation: A US Los Angeles-class submarine has detected a group of Russian ships with their active sonars turned on. The player has chosen to remain at intermediate depth, moving at 15 knots. The referee has placed the units just beyond the maximum range of their sonars, or just beyond the range at which they have a chance of detecting each other. The longest-ranged sonar is the American BQQ-5C, which is being used passively (its towed array is retracted).

Planning: mark starting positions with an X, and later positions with a dot. Be sure to write the time next to each ship's starting position.

Not every movement in the turn needs to be plotted, as long as the units are moving slowly and their positions don't change much. At the starting speed of 15 knots, the ship moves 1,500 yards (0.75 nm) per tactical turn. If a player plots his movement every other tactical turn (6 minutes), mark his ship's position every 3,000 yards.

The referee may also let the submarine move in tactical turns while the Russians use intermediate turns, if the players cannot be separated.

ASW operations take a great deal of time (in the real world) and ships move very slowly. Players can prepare orders in advance such as "advance at 15 knots on the same heading with sonar active until something is detected or until 1030." The Russian player has issued such an order here. The US player can simply say he continues to close the distance and plans to fire at whatever range he chooses.

Note: not all ASW scenarios are this one-sided.

Mr. Bond's Laws of Wargaming

1. Turns take the same amount of time whether they are 30 seconds, 3 minutes, 30 minutes, or 8 hours. Use long turns to speed up the game.

2. The fewer units that have to move, the better. Move formations as a group, move distant units multiple turns at once, and eliminate units that are effectively out of the game.

3. Ask your players what their plans are — not just their next move, but their intentions for the coming hour and the one after. This forces them to take a longer view and clarifies what they will have to do turn by turn.

4. The time a player needs each turn will increase exponentially as his options multiply.

2.6 Detailed Example: A Border in the Gulf

You will find the ship reference sheets and air data card for this example's units on pages 2-4, 2-5, and 2-6.

Operational Situation. Groups in Saudi Arabia backed by Iran are calling for the fall of King Fadh's regime. The US then considerably increases its aid to the Saudis, both to counter the domestic threat and to prevent ambitious neighbors from taking advantage of Saudi weakness. This support becomes a problem for the Iranians, who believe the US is using Saudi instability to increase its influence in the country. They have therefore decided to launch a surprise attack on the support ships — a political "Pearl Harbor" intended to hurt and embarrass the Americans.

Tactical Situation. A US cargo ship is carrying military and economic aid intended for the Saudis. It is escorted by an O.H. Perry-class frigate.

Environment. A typical day in the Gulf. Sea state 2 with 10-knot winds from the NW, clear skies (dawn at 0600) with 30% visibility. Acoustic conditions are poor, depth limited to periscope depth. There is low radar ducting.

US Forces. USS Halyburton (FFG-40) (O.H. Perry class), with 2 embarked SH-60B Seahawk helicopters, and a merchant ship.

US Orders. Prevent any incident involving the American convoy by locating and identifying any potential threat. If ships ignore warnings and enter a 75 nm exclusion zone around the US units, they are to be considered hostile and armed force may be used if they do not leave the zone.

US Victory Conditions. Tactical victory: prevent any damage to all US units. Strategic victory: same, plus having destroyed all units attacking the convoy.

Iranian Forces. 2 Houdong-class missile boats, 306 and 308, crewed by Pasdaran.

Iranian Orders. Attack the convoy currently transiting the Persian Gulf. Inflict as much damage as possible.

Iranian Victory Conditions. Tactical victory: destroy a US unit. Strategic victory: sink a US merchant ship.

Setup. The game begins at 0600, at dawn, with a US frigate steaming ahead to the West (270°T) at 15 knots. The merchant ship steams 2,000 yards behind. The US player has ordered an SH-60B to take off at 0600 fitted with two jettisonable auxiliary tanks to conduct reconnaissance. The Iranian ships are placed to the Northwest, at a distance unknown to the US player.

The scenario begins with 30-minute intermediate turns. The referee makes the detection rolls and reports detections to the players.

0600: The US player's SH-60 takes off, executing orders to position itself 30 nm ahead. Moving at cruising speed and low altitude, it will arrive on station and climb to medium altitude during the turn's movement phase.

The SH-60B is equipped with a 3rd-generation ESM. During the detection phase, the helicopter succeeds at an ESM detection on bearing 313°. The contact is identified as a Chinese Type 756 radar, associated with a Houdong-class missile boat, a small-size ship class. The ESM line-of-sight table on page 4-6 shows that the maximum detection range is 158 nm for a small ship and a 3rd-generation ESM. Had this happened before the helicopter climbed from low to medium altitude, the player would have known only that the contact was at most 73 nm away, which is the horizon for a low-altitude aircraft detecting a small ship. The chance of detecting a radar by ESM during intermediate turns is 100%.

Although the helicopter is itself using its radar, the ship is out of its range: the Iranian ships have only a 2nd-generation ESM with shorter range. While the 3rd-generation ESM, at medium altitude against a small ship, has a horizon of 158 nm, the 2nd-generation receiver has a range of 142 nm; the Iranians therefore detect nothing. The Houdong's actual distance is 156 nm from the helicopter, and 168 nm from the Halyburton. This information is known only to the referee.

0630: The US player orders the helicopter to head 330°T, at cruising speed and medium altitude, to investigate the source of the radar signal. All other units continue as before.

At the detection phase, the Seahawk no longer sees anything on radar. The possibility that a missile boat is cruising nearby prompts the US player to order the other Seahawk to arm with 2 Penguin ASMs and a jettisonable tank. This will take 9 minutes to arm (section 3.3.5.7). It will be ready to take off at 0639. Due to the helicopter's limited flight endurance, the player orders it to stand by on the flight deck.

The distance separating the helicopter from the Houdong has now shrunk to 98 nm, and both Houdongs have successfully intercepted the APS-124 radar. They continue straight on, radars silent, using their ESM to gauge the range.

0700: The US and Iranian players continue moving as before. The Iranians hope to encounter a US aircraft and ships, and until the helicopter intentionally changes course, they must be heading the right way. All units move normally. No detection is made.

0730: At the detection phase, the helicopter's APS-124 radar detects two small surface contacts on a heading of 120°, moving at 26 knots. They are in a line-abreast formation, 5 nm apart.

The APS-124 has a range of 64 nm against small ships (see Annex L or the Air Data Card), and at medium altitude the radar horizon is 106 nm (section 4.2). The lower value, 64 nm, is used, and at the end of the 0730 turn's movement phase, the distance drops to 39 nm, and 142 nm from the US ships. Radar detection during an intermediate turn is automatic.

Although the Houdong's radar is on, it only has a range of 19 nm against a medium contact and 12 nm against a small contact. This is increased by positioning the ships in line abreast, but the Iranians have no chance of detecting an air or surface unit. Even if the US helicopter were within detection range, the Type 756 is a surface-search radar, and it cannot detect an aircraft flying above low altitude. The ESM detection gives the Iranian player an idea of the helicopter's location, but he will not be able to detect it as long as it stays at medium altitude.

0800: With a location, heading, and speed, the US player decides to intercept the 2 suspected missile boats. Although he has not positively identified them, fishing boats do not move at 26 knots in formation and do not carry Type 756 radars. The US player notes that at a distance of 142 nm, the ships are only 67 nm from the exclusion zone.

He turns to heading 345°, increasing his speed to a maximum of 29 knots. He also orders his reconnaissance helicopter to close to visual range for a positive identification of the contact. The helicopter changes heading 30° to port and continues closing. He orders the merchant ship to hold its course and continue.

The referee decides to switch to tactical turns at this point, since the helicopter is less than 30 minutes from the Houdongs. He does not tell the players, since such information might start the Iranian player thinking. He checks the line-of-sight range. An aircraft can see a ship at 14 nm (section 4.5.2), but visibility is 30%, so the range should be reduced to 4.2 nm. The helicopter must close to this distance to visually spot the ships. To identify their class, the helicopter must close even further, to half the line-of-sight range (section 4.5.8), i.e. 2.1 nm.

0803: After movement, the distance separating the Houdongs from the helicopter is 32 nm. No new detection is made.

0806: After movement, the distance separating the Houdongs from the helicopter is 24 nm.

0809: After movement, the distance separating the Houdongs from the helicopter is 16 nm.

0812: After movement, the distance separating the Houdongs from the helicopter is 8 nm.

0815: After movement, the distance separating the Houdongs from the helicopter is 2 nm. The player had ordered the helicopter to stop as soon as it reached visual identification range. Although it could close further, there is no need to. During the detection phase, the referee informs the American player that the two ships are Houdongs. The Iranians spot the helicopter at the same moment.

0818: The Iranian player makes a decision. He knows he has been discovered, which means he has lost the first half of the battle. Firing on the helicopter would prematurely reveal his hostile intentions well before the 75 nm exclusion zone. On the other hand, he only knows that the American ships are cruising somewhere beyond and are probably not yet within firing range. Destroying the helicopter, hoping there are no others nearby, will guarantee breaking contact with the US player's other units and will secure him a tactical victory.

At the first movement phase, the Iranian player orders his ships to accelerate to full speed and head toward the helicopter. The US player had ordered his helicopter to hold its position in visual contact with the ships at a distance of 2 nm. This is within range of the portable Igla SAMs carried aboard the ships. Each Houdong fires one missile during the first fire phase.

At the detection phase, the US player sees the missile launches and orders the helicopter to begin evasive maneuvers. At the following second movement phase, the missile moves 4.5 nm while the helicopter flees 0.4 nm, placing it 2.4 nm from its attackers. That's close, but the missiles will reach their target at the second movement phase, before the helicopter is out of range.

The missiles have an ATA score of 4.0, against the helicopter's score of 1.5. Using the procedures in 6.4.1.2 and 6.3.3, the chance to hit is 4.0 − 1.5, or 55%. Rolling 2D100, the Iranian player gets 97 and 30, shooting down the helicopter.

The Iranians shut down their radar.

0818.5: The American player immediately orders the other helicopter to take off. It will launch at 0823.5. He would also like to launch his SSMs against the Houdongs, but they are out of range. He orders the merchant ship to slow from 15 to 10 knots, to delay its approach to the Iranian ships.

The Iranians, having won a tactical victory, could withdraw, but they would not then have accomplished their full mission. They continue their run at a speed of 34 knots.

Because it will take time and the units are in a position to interact again, the referee chooses to switch back to tactical turns. He moves the ships and the aircraft forward 2.5 minutes (5 engagement turns), to resynchronize with the tactical turns.

0821: All units move according to their orders.

0824: The second helicopter takes off, armed with 2 Penguin ASMs and a jettisonable auxiliary tank. This takes one minute of its travel time (at maximum speed and medium altitude) until its takeoff at 0823. This places it 2.5 nm from the ship, at low altitude, heading toward the Houdongs' last known position.

0830: All units move as before. The helicopter is now 7.5 nm ahead of the Halyburton at medium altitude. The Houdongs are 100 nm from the frigate and a bit less from the helicopter. Their location and exact range are known only to the referee, but the US player knows where his helicopter was shot down.

The Iranians are beyond the helicopter's radar range, and they are not emitting. The Iranians can detect the APS-124 on their ESM; they roll a 55 and a 42 with a 90% chance of detection during a tactical turn (section 4.3) as soon as it climbs to medium altitude. While the SH-60B was on deck, the Iranians had trained their ESM on the likely takeoff point and the presumed location of the US warship.

0833: The helicopter closes on the Iranian Houdongs at a combined speed of 184 knots, 150 for the aircraft and 34 for the missile boats. The closing speed of the US and Iranian ships is 63 knots, accounting for the frigate's 29-knot speed. The helicopter is now 83.3 nm from the Iranians, while the US ship is 96.9 nm away.

The Iranians continue to track the helicopter's radar.

0836: Movement as before. The helicopter is 74.1 nm from the Iranians and the US frigate 93.8 nm.

0839: Movement as before. The helicopter is 64.9 nm from the Iranians and the US frigate 90.7 nm.

0842: Movement as before. The helicopter is 55.7 nm from the Iranians and the US frigate 87.6 nm.

At the detection phase, the referee rolls for the helicopter's radar, which detects one of the missile boats (90% chance during a tactical turn — he rolls a 37 and a 92). The helicopter relays the information to the US ship.

0845: The US player chooses to continue as before. He is nearly within Harpoon range and will need to attack before the Houdongs are close enough to launch their C802s, with a 15.5 nm margin.

The Houdong player is tracking the Seahawk's radar and has a good enough fix on its position to guess it has been detected. At the planning phase, he orders both ships to turn on their radars.

0848: Movement as before. The helicopter is 46.5 nm from the Iranians and the US frigate 84.4 nm.

At the detection phase, the referee rolls to see if the helicopter's radar has found the second Houdong and gets just barely a 90. The referee also rolls for ESM detection of the Houdongs' radars, and the US player detects them.

0851: Movement as before. The US player orders the Seahawk to close to firing range of its Penguin missiles, but no closer.

0854: Movement as before. The helicopter is 28.1 nm from the Iranians and the US frigate 78.1 nm.

At the planned fire phase, with barely a dozen nm before the Houdongs can fire, the US player, within Harpoon range, decides to launch two Harpoon missiles at one of the Houdongs. A counter representing 2 missiles is placed on the playing surface adjacent to the ship.

0857: Movement as before. The Harpoon missiles launched the previous turn move 25.8 nm.

At the end of the movement phase, the Seahawk is 18.9 nm away, the Harpoons 50.6 nm, and the Halyburton 75 nm from the Iranian ships.

At the planned fire phase, the US player launches two more Harpoon missiles at the second ship. As with the first missiles, a Harpoon counter is placed on the playing surface adjacent to the ship. It will move for the first time next turn.

0900: Having fired his SSMs, the US player has no further interest in closing the distance with the Houdongs and slows to 15 knots. Since the helicopter was ordered not to close nearer than Penguin firing range, it takes position 8 nm from the Houdongs, tracking them by radar. The US player, knowing Harpoons have been fired at each missile boat, tells the Seahawk pilot to hold his fire while he watches the results of the attack, so he can use his missiles to finish off any survivors.

0903: At the end of movement, the first pair of Harpoons reaches its target, Houdong 306. The second pair of Harpoons is 49.2 nm away, the helicopter 13 nm, and the Halyburton has closed to 70.1 nm.

The Iranian ships would have needed more elaborate AA defenses to engage the missiles over several engagement turns. In reality, their only weapon capable of engaging the Harpoon missiles is their mounted Model 69 30mm/65 gun. It has a range of 1.5 nm, which represents less than 30 seconds of movement for a Harpoon (4.3 nm). In this case, the delayed-impact rule (section 3.4.5) grants the 30mm one shot (at one Harpoon) — that's all the ship is allowed to do.

At the planned fire phase, the Iranian player consults his Ship Reference Sheet. The chance of hitting a close-in air target is 20%. This score, however, is reduced because the Harpoons are flying sea-skimming and because the Chinese Model 69 30mm/65 gun cannot fire at sea-skimming targets (section 6.4.1.1, anti-aircraft guns). The hit chance is halved for this reason, dropping to 10%. This chance is further reduced by 15% due to the Harpoons' very small signature. This drops the hit chance to −5%, but players always have at least a 1% chance to hit. The Iranian player fires and rolls a 56.

The Harpoon attack can now be resolved. 2 3rd-generation-radar missiles attack a small ship equipped with 2nd-generation decoys. Referring to the anti-ship missile attack table on page 6-5, the US player finds the Small Target Signatures table and applies the defense system's generation (2nd-generation ECM), the missile's generation (3rd), and uses the decoys-only column. The chance to hit is 60%. Rolling 2D100, the US player gets 13 and 16, so both missiles hit the Houdong. The Iranian ship can absorb 5 damage points, and each Harpoon inflicts 45, so Houdong 306 is annihilated.

0906: At the movement phase of this tactical turn, the second pair of Harpoons reaches Houdong 308. As in the previous turn, the Iranian player attempts a desperate shot with his 30mm at a 1% chance of success and misses with an 83. The US player rolls for his Harpoons, which have a 60% chance to hit. He gets 89 and 65, meaning both miss their target. These Harpoon variants have no reattack capability, so they continue on until they find another target or run out of fuel.

At the end of the movement phase, the Iranian player is at a distance of 67.6 nm. The US helicopter is positioned 8 nm away. At the detection phase, it is close enough to see, both visually and on radar, that the second Houdong is still operational. It then fires its 2 Penguin missiles during the reaction fire phase.

0909: At the movement phase, the 2 Penguins cover half the distance they should, since they were fired during the reaction phase: 528 knots/20, then divided by 2, or 13.2 nm. This means they will reach the Houdong at the movement phase. The Iranian captain can therefore fire once more with his 30mm. He rolls a 62.

The Penguin Mk2 Mod 7 is a 2nd-generation IR missile, not 3rd-generation like the Harpoons. Terminal IR-guided missiles are not affected by jammers. Consequently, the absence of a jammer aboard the Houdong is not a handicap for the Iranian. On the anti-ship missile attack table, a 2nd-generation missile against 2nd-generation decoys has a 49% chance to hit. The US player gets 78 and 25. The second missile therefore hits the missile boat and inflicts 24 damage points, enough to end the Iranians' career plans by sinking their ship, which could only absorb 5 damage points.

In the following turns, the US helicopter can conduct SAR (search and rescue) operations looking for the US helicopter crew and the Iranian crews of the sunken ships.

Had the Houdongs survived another tactical turn or two, they would have been within firing range, but would have had no precise idea of the US frigate's exact location. "To the Southeast" is not a valid firing solution, even for a snap shot.

This scenario is not meant to be balanced, but is intended to demonstrate the use of turns of different lengths, radar, ESM, and anti-air and anti-ship missiles. Both sides aggressively used the information gained from their detectors and weighed their tactical options against their victory conditions.

Chapter Three – Movement

Ships, submarines, aircraft, missiles, and torpedoes move during the movement phase of intermediate and tactical turns, and during the first phase of engagement turns. Aircraft and missiles, if engaged with other units, also move during the second movement phase of the engagement turn.

3.1 Ship Movement

Ships and submarines have a maximum speed given in Annex A, which may be reduced by damage.

When a ship is damaged, consult the Damage and Speed Breakdown Chart on the Ship Reference Sheet. The more damage a ship accumulates, the more its speed is reduced. Every 25% increment of its maximum damage-point total lost reduces its speed by 25%, until it reaches 90% damage, at which point its speed drops to zero (it drifts on the water). The ship sinks once it reaches 100% damage.

Ships are subject to restrictions on their speed and heading changes based on their size. The speed-change table gives the limits on a ship's speed and heading changes.

3.1.1 Speed Change. Ships have a limit on how quickly they can change speed. Their ability to accelerate or decelerate depends on their size and on whether or not they have controllable-pitch propellers (CPP). All ships fitted with CPP have their propulsion type noted in Annex A, e.g. "Diesel/CPP."

The speed-change table lists the acceleration and deceleration limits for each size class in a tactical turn. To get the rates for an engagement turn, simply divide by 6.

Submarines wishing to move quietly may only accelerate/decelerate by 50% of the speed given in the table. Any greater acceleration or deceleration will increase their noise level (see section 4.4.5).

3.1.1.1 Crash Back. Ships can brake faster than the normal limits allow by executing a Crash Back. The machinery is reversed and the deceleration rate is doubled. There is a 5% chance that this maneuver causes critical damage to the machinery. All ships executing a Crash Back cavitate.

3.1.1.2 Reverse. Maximum speed in reverse for any surface ship equals half its maximum forward speed. Submarines cannot go in reverse. A ship going in reverse has a 50% chance of losing its towed sonar array, if deployed, for each tactical turn it spends in reverse. It also has a 10% chance that its propeller becomes fouled by the sonar cable (treat as critical damage to the machinery).

3.1.1.3 Weather Effects. As wind and weather increase wave height, a ship pitches and rolls. In very rough weather, the ship plunges down the face of a wave and then slams into the next one. The impact can damage sonar domes, the rudder, and even buckle hull plates in the most severe cases. It also means the crew is especially shaken about.

As sea state increases, ships must slow down to prevent pitching. If the weather is too rough they must heave to, turning their bow into the wind and slowing to the bare minimum (3-5 knots). If this is combined with a strong headwind, they will be stationary.

Consult the Sea State/Speed table to see how fast a ship can move based on sea state. Cross-reference the ship's size with the sea state. An "M" means the ship can move at maximum speed. A fraction — 3/4, 1/2, or 1/4 — means the ship cannot move faster than that fraction of its maximum speed. An "H" means the ship must heave to and prevent pitching. Machinery damage can also restrict a ship's speed, but the fraction of the ship's speed is calculated from its original, undamaged speed.

Key: M = Maximum speed, no restriction. H = The ship must heave to.

3.1.2 Heading Changes and Turns. A ship needs a minimum distance to turn. Called "Advance," this is the distance the ship travels on its original heading until the rudder takes effect and it changes direction. Larger ships need more room than smaller ones.

Even if the ship has held a straight course for several turns, the player must still advance the specified distance before changing heading. The Advance is the distance traveled after the rudder has been put over to turn. If a player knows one or more turns in advance that he will need to turn at a particular point, and has enough room to maneuver, he may order the turn in advance on his order sheet. At that point, the ship will be allowed to turn from the start of movement.

In most cases, such as maneuvers on the open sea, advance distances are not a problem. Other times, such as at reduced speeds or in straits, the exact distance is very important. When navigating narrow channels, good navigators will not only mark the turning point, but will also precalculate the advance point and note it on the chart. The order to turn is given at that point.

Modern ships do not always fight at high speed. During ASW operations, they spend a lot of time at very low speed, listening with passive sonar. The number of turns it takes to train guns or turn to avoid a torpedo then becomes critical.

The ship turning-distance table lists most advances for each ship by size class for a normal and a tight turn. Most turns are executed normally, but in emergency situations, a ship can turn a bit tighter by "exceeding the limits." There is a 5% risk (5 or less on a D100) that the rudder breaks. If it fails, treat it as a "critical hit to the rudder." The ship continues circling until the "critical hit" is repaired.

Unless otherwise noted, all turns are considered to use "standard rudder."

Submerged submarines have their advance distance classed according to their size class.

Merchant ships are less maneuverable than warships and have their own table.

Note: Some ships are equipped with "bow thrusters," small, steerable, submerged electric motors. They are very small but can be used at low speed to give the ship's bow extra thrust. They are only used in port for maneuvering, not at full speed.

Ship Turning-Distance Table. Example: a frigate (small size class) is moving at 30 knots. It needs 200 yards before it can turn. At a scale of 2 inches to 1 mile, or 1 inch to 1,000 yards, the player moves the ship 2/10 of an inch and pivots 45°. It can spend the rest of its movement continuing in the same direction, or it can advance 200 yards and turn again.

Ships also suffer a loss of speed when turning due to rudder and hull drag. The amount of speed lost per 45° heading change is given in the "ship turning distance" table. In most cases, the speed loss will be regained during the Tactical Turn unless the ship is moving slowly and making many maneuvers. The "Speed Change" table (see also section 3.1.1) shows a ship's ability to accelerate within a 3-minute Tactical Turn. For example: a medium-size destroyer, moving at 35 knots, makes a normal 45° turn, causing it to lose 2 knots, while it has an acceleration of 5 knots per Tactical Turn. If the ship's total speed loss exceeds its acceleration capacity, its speed is immediately reduced by the difference.

Example: a small frigate begins its movement phase at a speed of 30 knots and makes 2 standard 45° turns, slowing the ship by 4 knots total. It can accelerate by 8 knots (we are above half maximum speed), so the acceleration will offset the loss from turning. Had it made a series of 5 45° maneuvers, losing 10 knots, the engines could only make up 8 knots, reducing the effective speed to 28 knots.

3.1.3 Maneuvers Permitting Flight Operations. Ships must maneuver in specific ways to allow certain air operations.

3.1.3.1 Aircraft Carriers. Carriers add their own speed to the wind speed to give fixed-wing aircraft optimal launch conditions. This lets aircraft carry a heavier load or have greater launch safety margins. Many carriers have angled decks, at the bow or stern, allowing takeoffs and landings while heading directly into the wind or with a 10° crosswind from port. The sum of the ship's speed and the wind speed must equal 30 knots (see Annex N, environment). Ships fitted only with forward and aft flight decks (e.g. Invincible) must head directly into the wind. Ships with large landing areas (LPH, LHA, CV, CVH) allow helicopters and VTOL aircraft to take off with wind from any direction.

3.1.3.2 Ships with a Helipad. Ships fitted with a helipad must steam with a 30° starboard crosswind. The sum of the ship's speed and the wind speed must be 30 knots. The wind must not come directly from ahead or astern because of turbulence caused by the ship's superstructure and exhaust gases. Approaching from the starboard bow gives the helicopter pilot the best view of the landing area.

3.2 Submarine Movement

Submarines maneuver on the surface like surface ships. Because most of a submarine is submerged even when surfaced, it has a very deep keel. Submarines cannot submerge in less than 20 fathoms of water and cannot operate in less than 5 fathoms of water.

3.2.1 Depth Changes. Submarines can change depth, moving between specific depth levels. The illustration on page 3-4 shows the various depth levels. The submarine depth-levels table gives the exact depths for each level.

Submarine Depth Levels. The periscope/snorkel level is a special level that is part of shallow depth, to which special detection rules apply (the submarine can raise a mast, but is easier to detect).

A submarine can change depth by planning the level it wants to reach as a movement order written on the Log Sheet. Depending on its speed, a submarine may take several tactical turns to reach its target level. The submarine speed/levels table lists the number of zones a submarine can cross based on its speed.

Submarine Speed/Levels Table

Speed	Number of levels crossable
1-10 knots	2
11-20 knots	3
21-30 knots	5
31 knots and up	8

Example: a submarine at 25 knots at shallow depth can dive to intermediate level V.

Submarines can perform emergency surfacing, which lets them rise as if they had one extra speed bracket. Submarines moving at 31 knots do not benefit from emergency surfacing because they are limited by the hull's resistance to level changes. Submarines executing an emergency surfacing must rise at least 3 levels and cavitate.

The sea surface is not considered a level for submarines changing depth. Once the submarine is at shallow depth, it may surface, but this is a separate operation.

3.2.1.1 Surface. Submarines rarely operate at this depth, but may need to surface due to damage or to carry out a special movement.

To surface, a submarine must be at periscope depth or shallow depth at the start of the turn. It takes a submarine 3 minutes (one tactical turn) to surface. It may use its maximum surface speed during the movement phase of the turn in which it surfaces.

Submerging takes 3 minutes (one tactical turn). The submarine's player must declare whether he is submerging to periscope depth or shallow depth. He may use his maximum submerged speed the turn after submerging.

3.2.1.2 Periscope Depth. This is a special sub-level of shallow depth with its own specific detection and combat rules. The submarine is very close to the surface. A submarine player entering shallow depth must declare whether he remains at shallow depth or goes to periscope depth. The submarine may switch between shallow depth and periscope depth on each engagement turn by ordering it during the planning phase.

The submarine is submerged, but close enough to the surface to use its periscope, snorkel, and radar and ESM masts. It can fire submerged-launch missiles and mast-mounted SAMs. A submarine cannot deploy its snorkel, periscope, or masts if its speed exceeds 15 knots. If all masts are retracted, it can move at its maximum submerged speed.

A submarine at periscope depth is visible (by day) as a dark shadow in the water; this shadow is visible to aircraft flying at low altitude up to 1.5 nm away during the detection phase. This distance is reduced by visibility conditions. See section 4.5.4 to resolve detection.

If a submarine moves at 8 knots or more at periscope depth, it leaves a visible wake on the surface. This "Kelvin wake" is produced by the hull and is present even if the periscope is retracted. This is visible to aircraft flying at low or medium altitude at a distance of up to 3 nm, for sea states between 0 and 3, during the detection phase. A submarine does not produce a visible "Kelvin wake" below periscope depth. See section 4.5.4 to resolve detection.

3.2.1.3 Shallow Depth. The submarine is above the thermocline, but is less detectable than at periscope depth. It can fire submerged-launch missiles. It cannot use its periscope or its other mast-mounted detectors.

The thermocline is a boundary layer separating two water masses of different temperatures that affects sound propagation. Sonar range across the thermocline is reduced.

3.2.1.4 Intermediate Level. The submarine is below the thermocline (layer), thereby reducing its chances of being detected by surface ships. The thermocline is a layer marking a sharp temperature change between 2 water levels that can bend/deflect sound. The submarine's sonar range for detecting surface ships is reduced, and other detectors cannot be used to find surface ships.

The intermediate level is divided into 5 sub-levels, I, II, III, IV, and V. The submarine can move between these sub-levels (depending on its permitted depth), but the player must constantly record which sub-level it occupies. For some submarines, this is the last sub-level that can be safely reached.

3.2.1.5 Deep Level. This is the maximum level most submarines can safely reach. This level is used by submarines to escape detection or weapons fired at them.

The deep level is divided into 5 sub-levels, I, II, III, IV, and V. The submarine can move between these sub-levels (depending on its maximum permitted depth), but the player must constantly record which sub-level it occupies.

3.2.1.6 Very Deep Level. The submarine is at a greater depth than the deep level. Only submarines expressly authorized to operate at this depth level by the ship listing in Annex A can move to this level.

3.2.2 Movement of Submerged Submarines. Undetected submarines move with reference to a point arbitrarily fixed on the playing surface. Submerged submarine movement is plotted on a sheet of graph paper (the recommended scale is 10 squares/inch, with one square side equal to 500 yards). The submarine's starting point may be determined randomly or by mutual agreement. The submarine player will keep track of the other ships and will tell his opponent when the submarine is detected. Submarines that are detected but submerged are represented by a counter and move normally. If contact is lost, remove the counter from the playing surface, or leave it at its last known position (the "datum").

3.2.3 Diesel Submarine Battery Endurance. Nuclear submarines can maneuver underwater indefinitely at whatever speed they choose. Diesel submarines, on the other hand, suffer from much greater limitations.

A diesel submarine currently uses "diesel-electric" propulsion. When surfaced, or when using its snorkel, it runs on its diesel engine and can devote part of the power it produces to recharging its electric batteries. Diesel propulsion is noisy and easy to detect. When submerged, the submarine uses electric motors, which are nearly completely silent.

The batteries can supply a low-intensity current, sufficient to maintain a slow patrol speed for several days. On the other hand, if the submarine moves at full speed, the charge in those same batteries will only last about an hour. In the game, each diesel submarine's battery endurance is expressed in "charge units." This is the number of hours its batteries will last at five knots. At higher speeds, the consumption rate increases rapidly.

For the most part, battery endurance will be used up as players execute intermediate turns (30 minutes) or tactical turns (3 minutes). To determine how much the battery has discharged in an hour, take the submarine's average speed over the last two intermediate turns or the last 20 tactical turns and apply the result to the battery charge/discharge table.

Example: a Type 209 submarine, with 64 (out of 75) charge units in its batteries, tries to gain a firing position against a merchant ship moving at 12 knots. To do so, the submarine must accelerate to 16 knots for one intermediate turn, then to 12 knots for the next. The average speed during this hour of movement is 14 knots, which corresponds to 12 charge units, which must be deducted from its batteries. Once the hour has elapsed, the battery will have only 52 charge units in reserve (69%).

A submarine can recharge its batteries by running on the surface or at periscope depth with its snorkel mast raised. If it moves at up to 50% of its maximum speed, it can recharge at the maximum rate. If it moves at half that speed, the recharge rate is halved.

Battery Recharge Table

Battery Level	Recharge Rate (units/hour)
0-70%	20
71-100%	10

Example: after a successful attack on the merchant ship, the Type 209 comes to periscope depth, raises its snorkel and ESM masts and one of its periscopes, and begins recharging its batteries. The submarine's batteries have 33 charge units (44%), and the captain chooses to move at half his maximum speed. After two hours, the ESM system detects a maritime patrol aircraft's radar. The submarine's CO retracts the masts, including the snorkel, and orders a deeper dive. During those two hours, the submarine recharged its batteries by 30 charge units. During the first hour, the submarine was able to recharge at 20 units per hour because its starting level was 44%. The 20 charge units accumulated during that hour bring the battery's charge to (33+20) / 75 = 70%. The second hour will see the recharge rate slow to 10 units per hour, since the battery's charge level has reached 70%. The 10 units per hour will then bring the battery to 63 units, or 84%.

3.2.4 Air-Independent Propulsion (AIP). This is a new technology that lets a diesel-electric submarine stay submerged for longer periods by giving it the option of using an alternative power source for low-speed operations. If the submarine's speed is 7 knots or less, the AIP system may be used to recharge the battery. Although not as flexible or as powerful as nuclear propulsion, AIP submarines are less expensive.

The technologies are still under development, but include fuel cells, Stirling engines, and sometimes small nuclear reactors. In Annex A, submarines fitted with air-independent propulsion systems are marked "AIP-Electric."

Air-independent propulsion systems can supply up to 3 charge units/hour to power the submarine. The total potential output of an AIP system is 400 charge units. Once this output has been used up, the submarine must return to port to replenish its fuel and oxygen tanks.

Example: the Swedish Götland-class (A-19) submarine is fitted with a Stirling-engine AIP system. If it needs to move at 4 knots, the battery will let it maintain this speed for 100 hours, or 4.2 days. With the AIP system, the Götland can maintain a speed of 4 knots for 500 hours (100 hours of battery plus 400 hours of AIP system), or about 3 weeks. On the other hand, if the Götland moves at 9 knots, the submarine's endurance will be 167 hours, or about 7 days, after which the battery will be drained and the AIP system will need to be replenished.

3.3 Aircraft Movement

Aircraft move at greater speeds than ships or submarines. They move twice during each engagement turn, during the first and second movement phases. Aircraft movement during the second movement phase is planned at that time, just before it is executed.

Air-Independent Propulsion (AIP). Submarines with diesel-electric propulsion systems have limited submerged endurance because they depend on electrochemical storage batteries as their main power source. Because electric propulsion motors deliver power proportional to the cube of the submarine's speed, submarines that can move for several days at 5 knots will only be able to sprint for 1 or 2 hours using the same charge. Of course, no submarine commander will let his batteries run flat in combat, so the endurance he can count on for sprinting is far lower than that. Once the submarine's batteries are exhausted, it must "snort" to recharge them. It must surface or come to periscope depth to do this, and the submarine then becomes far more vulnerable to detection by passive sonar, radar, and infrared detectors. At the same time, its own sonar will be less effective.

Several approaches have been tried to reduce this vulnerability, but all involve, in one form or another, an air-independent propulsion (AIP) system. This is an alternative propulsion system that uses liquid oxygen stored in refrigerated tanks. The fuel may be diesel fuel or hydrogen gas, but all AIP systems are based on combustion that requires a source of oxygen. AIP's main advantage is that it can significantly increase low-speed endurance, but it has only a marginal effect when the submarine operates at high speed.

For the most part, the various AIP systems offer roughly the same increase in low-speed endurance. At a speed of 5 knots, an AIP system can improve submerged endurance by a factor of five. As a result, instead of a submerged endurance of 4 days, a submarine fitted with AIP can remain submerged for 20 days. However, if the submarine's speed increases, the AIP system cannot keep up with the propulsion motor's demand, and the battery will again supply most of the power. At high speed (20 knots and above), an AIP system will supply less than 10% of the power needed by the main propulsion motor and will have virtually no impact on the submarine's endurance.

Since a submarine spends about 75% of its time on patrol, with only occasional high-speed bursts, AIP systems can offer an improvement in submerged endurance, as long as the submarine does not need to move very fast or very far. This is ideal for littoral submarines.

Aircraft can change heading or altitude during each of the two phases. Planned aircraft movement can include speed and heading, altitude, altitude changes, turns, and takeoff or landing orders.

Aircraft can enter or leave the battle area and thus the game. Note the positions of off-map air units.

3.3.1 Dogfighting. It is possible to plan for aircraft to enter close air combat. The order to plan is "dogfight," and the decision to accept or decline a dogfight is indicated at the start of each movement phase. Aircraft involved in a dogfight do not plan their movement. Instead, they move randomly (see 6.3.3.3). If one of the aircraft attacked in a dogfight does not engage in the dogfight, then the other, dogfighting aircraft moves along with it. Examples of this include cruise missiles, hovering helicopters, bombers in formation, and any air unit that, for whatever reason, does not wish to maneuver against the other aircraft but wishes to continue on its course.

3.3.2 Speeds. Aircraft speeds are affected by altitude. The denser air at low altitude slows jet aircraft and forces them to burn fuel faster than at high altitude. Air above 11,000 meters lets them fly at maximum speed, but is too thin for turboprop aircraft or helicopters. These operate more efficiently in the denser air near sea level.

All aircraft operate at two or three speeds:

• Cruise speed. The most efficient speed for covering the greatest distance. It is normally around 75% to 80% of maximum engine power.
• Full military power. This is 100% of engine power without afterburner. As such, most aircraft will fly at their maximum speed, which can be up to 50% higher than cruise speed. However, they will burn two to three times more fuel. Hovering helicopters must use full military power.
• Afterburner. Some aircraft, generally high-performance jets, are equipped with afterburners. This equipment increases aircraft speed beyond full military power by injecting fuel into the jet exhaust. This lets them abruptly double their speed, but burns their fuel more than twenty times faster than at cruise speed.

Players controlling aircraft in Harpoon must declare which of these three speed types they are moving at. This speed type determines how fast the aircraft flies and how fast it burns fuel. Fuel consumption due to acceleration is explained in section 3.3.6.3.

Aircraft usually combine these speed types over the course of a mission. A fighter will use full military power for a few minutes at takeoff, then throttle back to cruise speed until it approaches its objective. Near its objective, it will accelerate to full military power and carry out its attack. It may also use brief bursts of afterburner if engaged in air combat, or to escape the target area more quickly. Finally, it will use cruise speed to return to base.

Aircraft must move at least 20% of their maximum speed to maintain altitude, except for fixed-wing VTOL aircraft and helicopters during their transition phase between forward flight and hovering. Hovering helicopters and fixed-wing VTOL aircraft must remain stationary while hovering.

Aircraft carrying more than 60% of their external payload, which includes auxiliary tanks, cannot exceed the speed of sound. This is 5.5 nm/engagement turn at very low altitude (V/low), 5.4 nm/engagement turn at medium altitude, and 4.8 nm/engagement turn at high and very high altitude.

3.3.2.1 Speed Change. An aircraft can accelerate up to 10% of its ATA value times its maximum speed (for that altitude) at full military power during a movement phase. If an aircraft is using its afterburner, use its afterburner speed value instead. No aircraft can accelerate beyond its maximum speed. It can decelerate by 20% of its maximum speed at the start of a phase. If an aircraft is changing altitude level during a phase, use the slower of the two maximum speeds when calculating acceleration or deceleration.

Example 1: An E-3 Sentry (ATA of 0.5) has a maximum speed of 460 knots at high altitude. It can accelerate by 0.5 x 10% x 460 knots, or 23 knots, during a 15-second movement phase.

Example 2: A lightly loaded F-16C Falcon (ATA of 4.5) has a maximum speed of 735 knots at full military power at high altitude. It can accelerate by 4.5 x 10% x 735 knots, or 331 knots, during a 15-second movement phase (yes, it can, I was there).

Not feeling fast enough, the F-16 pilot chooses to use afterburner. His acceleration becomes 4.5 x 10% x 1,158 knots, or 521 knots, that phase.

3.3.2.2 Hovering. A helicopter can hover at very low altitude at a speed of 0. To hover, the helicopter must be at very low altitude (or above land). The player then plans "hover" as the movement. Both movement phases of the tactical turn must be used to complete the transition to hovering flight. During the movement phase of the next turn, the helicopter will be hovering.

During this type of flight, the helicopter remains stationary and collision risk is handled as if it were a ship (see 3.6). It is then treated as a sea-skimming air target or as a surface target (at the firer's choice), including during the transition phase (in either direction). Its engines are at full military power while hovering, including during the transition phase (in either direction).

A helicopter must move downwind when it ends its hover.

3.3.3 Heading Changes and Turns. Each aircraft has an air-to-air defense value (D-ATA) given in Annex B of the aircraft listing. An aircraft with a D-ATA of .5 can turn 90° in one phase. All others, including helicopters, can turn up to 180° in one phase, or in other words, take whatever heading they want.

3.3.4 Altitudes and Altitude Changes. Aircraft and missiles can be at one of 5 general altitude levels: very low, low, medium, high, and very high. The altitude table gives the characteristics of the different altitude levels. Piloted aircraft must record their exact altitude (normally in hundreds of meters); different climb rates will lead aircraft to reach the various altitude levels at different times. Aircraft can change altitude by climbing or descending. The altitude-change table gives the climb value assigned to each aircraft type. Missiles or other air units at very low altitude are considered to be sea-skimming.

Aircraft climbing at more than 50% of their maximum climb value cannot accelerate at the same time. Aircraft diving at more than 50% of their maximum descent value can double their acceleration rate and increase their speed by 150%.

Altitude Table

Altitude Level	Feet	Meters
Very High (V. High)	44,621-65,617	13,601-20,000
High	24,607-44,620	7,501-13,600
Medium	6,563-24,606	2,001-7,500
Low	329-6,562	101-2,000
Nap of Earth (NOE)	99-328	31-100

Over land only. Dangerous for aircraft.

| Very Low (V Low) | 0-98 | 0-30 |

Over sea only. Dangerous for aircraft.

Altitude Change Table

Aircraft Type	Climb per Phase (meters)	Descent per Phase (meters)
Helicopters	150	225
Four-engine aircraft	150	225
High-performance aircraft (lightly loaded or unloaded)	1000	1500
All other aircraft	500	750

Note: aircraft with a lightly-loaded ATA value of 2.5 or better in Annex B are considered "high-performance."

3.3.4.1 Very Low Altitude / Nap of Earth (NOE). This special altitude level is part of the low-altitude level, but allows flying close to the surface of the ground or water, with risks. Very low altitude runs from sea level to 30 meters above the waves. Nap-of-earth altitude (NOE) covers the 31 to 100 meter band.

An aircraft flying at very low altitude literally skims the surface of the sea. Many cruise missiles, such as the Exocet, fly at this altitude. Aircraft run a collision risk against ships and terrain if they come within 500 yards (0.25 nm) of them (see section 3.6). At very low altitude, aircraft CANNOT use their terrain-following radar as a navigation aid. Most terrain-following systems have a minimum operating altitude of 30 meters (100 feet) or more.

Aircraft flying over land can use nap-of-earth (NOE) flight to hide by hugging the contours of the terrain between 31 and 100 meters above ground level. Note that both the resolution and the risk of NOE flight are similar to very low altitude flight over water, except that the maximum altitude is 100 instead of 30 meters. There is also a minimum altitude of 30 meters. Flying below 30 meters over land gives the aircraft no additional protection, and the risk of crashing becomes extremely high.

From this altitude, aircraft can only strafe, fire unguided rockets, and drop gravity bombs. They cannot fire guided missiles or drop guided weapons. Delayed-fuze bombs (weapons fitted with retarding fins) can be dropped without penalty. Non-retarded ordnance has a 50% chance of reaching the ground without exploding, and, if the bomb does explode, a 10% chance over water and a 25% chance over land of damaging the aircraft that dropped it. Bombs that do not explode only inflict 25% of their damage value on their target.

Aircraft at very low altitude (NOE) cannot exceed 650 knots (Mach 0.98), or 32.5 nm per tactical turn, or 2.7 nm per movement phase of an engagement turn.

3.3.4.1.1 Helicopters. Rotary-wing aircraft can fly at very low altitude (NOE) without restriction.

3.3.4.1.2 Hovercraft. Hovercraft do not actually fly but move on an air cushion. They can operate at very low altitude without restriction.

3.3.4.1.3 Conventional Aircraft. Fixed-wing aircraft, especially jets, have problems when flying at very low altitude. They are much faster and can correct their altitude less finely than helicopters, so flying them requires the pilot's full concentration. Turbulence at very low altitude is also very strong and can force an aircraft to quickly change altitude. Entering even a slight turn increases the risk of suddenly losing altitude. The risk is sometimes justified by the desire to reduce the risk of detection by lowering the radar horizon and preventing certain weapon types from engaging the aircraft.

NOE flight is very hazardous and demands the pilot's full attention. At speeds above 400 knots, the terrain streaming beneath the aircraft becomes a blur, and the effect is similar to flying through a tunnel. The aircraft is considered to be at the low-altitude level, but must constantly maneuver to stay close to the ground.

There is a chance that a fixed-wing aircraft will crash if it flies at nap of earth, unless it is fitted with an obstacle-avoidance radar or a terrain-following radar. This is due to turbulence, unexpected terrain, and enemy activity. This crash probability must be checked with a die roll on every engagement turn during which the aircraft flies at nap of earth. The crash probability is given by the very low/NOE crash table (based on the aircraft's speed).

Modifiers:

• +2% if the aircraft turns more than 30° during an engagement turn.
• +3% if the aircraft is the target of a guided missile, OR
• +2% if the aircraft is the target of anti-aircraft artillery fire (AAA, which includes infantry weapons)

See also section 6.3.7, pilot experience modifiers (optional rule).

Only one of the last two modifiers may be applied during an engagement turn. If the aircraft is targeted by both missiles and anti-aircraft artillery, use only the guided-missile modifier.

The roll is made at the end of the engagement turn, and is based on the aircraft's movement and the attacks made against it during that turn.

Example: an Argentine Dagger is about to attack a Royal Navy Type 42 destroyer armed with Sea Dart missiles in the Falklands Strait. The Dagger has a maximum speed of 725 knots at very low altitude. It approaches its target at 725 knots at low altitude. As it comes within range of the Sea Darts' engagement envelope, it drops to very low altitude and must immediately slow to 650 knots, since no aircraft can move at Mach 1 at very low altitude. It moves 5.4 nm during this engagement turn. At the end of the turn, there is an 8% chance the aircraft crashes into the sea. It will use another engagement turn to approach the target, and at the end of that turn the crash probability will again be 8%. On the following turn, the aircraft turns 45°. Its crash probability will then be 10% (8% for its speed above 551 knots at very low altitude, plus 2% because it turns more than 30°).

The pilot takes the risk because the Sea Dart missile system has a very low probability of hitting a target at very low altitude. Likewise, most anti-aircraft guns have a reduced chance of hitting their target if it is sea-skimming.

On the next turn, it comes within range of the ship's defensive weapons. It is targeted by Sea Darts but is not hit. Its crash probability is now 11% (8% plus 3% for having been attacked by Sea Darts). The ship's anti-aircraft (AA) guns also open fire, but the larger +3% modifier subsumes the +2% AAA modifier. The two modifiers are not cumulative. Even though the firing player knows the missile has little chance of hitting its target, the pilot has no certainty of coming through unscathed. Under the pressure of combat, the pilot is not at all sure of the exact type of missile fired at him, let alone of the problems posed by his altitude.

After attacking the Type 42, the pilot enters within 0.2 nm of the Canberra, under fire from various infantry weapons deployed on deck. The crash probability is then 10% (8% plus 2% for being exposed to AAA fire). The Dagger pilot must also check for a possible collision with the Canberra (section 3.6) before disengaging from the ship, climbing slightly to low altitude, and disappearing over the horizon.

3.3.4.2 Low-Altitude Flight over Land. An aircraft flying over land must account for natural terrain and man-made structures. All terrain-related specifics apply at the low-altitude level. There is no very-low-altitude level over land, except for beaches or other specific terrain defined during scenario setup.

Aircraft at the low-altitude level over land must have a method or means of guiding their flight over the terrain. This can be done by eye (when visibility is 25% or better), by an infrared imaging system (such as FLIR — in clear weather with visibility of 10% or better), or by an obstacle-avoidance radar or terrain-following radar (in any visibility condition). Use of a radar can be detected by ESM. Failure to avoid an obstacle results in the aircraft's elimination, due to its interaction with the land/air interface and its infinite coefficient of friction.

3.3.5 Aircraft Takeoffs and Landings. Some aircraft can land on and take off from carrier flight decks, helipads, the sea surface, as well as from the ground. Takeoff and landing are activities planned for both the aircraft and the ship involved. Players may order an aircraft launch during any type of turn: engagement, tactical, or intermediate. An aircraft can take off or land during any movement phase of an engagement turn.

3.3.5.1 Carriers and Flight Decks. A carrier is a ship of any type that has a flight deck. A flight deck may be straight (HMS Invincible), angled (Russian Kiev), or dual (USS Nimitz). Flight decks may have catapults to assist in launching fixed-wing aircraft. A carrier may have an arrestor wire to catch, stop, and hold a landing aircraft. Flight decks are noted in Annex A as straight, angled, or dual. For example, the Midway class has a dual flight deck.

3.3.5.2 Helipads. Ships fitted with a helipad are permitted to launch and recover helicopters and fixed-wing VTOL aircraft. The presence of helipads is given in the weapons or remarks section of the ships listed in Annex A. They are identified by their location (aft, midship, forward). The first number is the number of helicopters that can be carried; the number in parentheses is the number of helicopters that can take off or land at the same time. Additional information is given in the remarks section. For example, a Spruance-class destroyer is fitted with an aft pad (1) 2; one helicopter can take off at a time and it can carry two. Helipads may be fitted with recovery systems (typically Bear Trap or RAST type) that assist helicopters in landing. Small fixed-wing VTOL aircraft can take off from and land on helipads; however, they cannot use the recovery systems.

3.3.5.3 Sea Surface. Seaplanes and helicopters fitted with floats can take off from and land on the sea surface, subject to restrictions based on sea state.

3.3.5.4 Aircraft Takeoff. Aircraft can normally take off safely from ships in sea state 3 or less. There is a 20% chance per sea-state level above that of the aircraft crashing into the water on takeoff. The safe sea state can be increased by ship equipment or features listed in the safe sea state table.

For example, the Iowa is a large ship able to absorb more than 450 damage points; it allows a helicopter to take off safely in sea state 5. In sea state 6, the helicopter will have a 20% chance of crashing on takeoff.

3.3.5.4.1 Catapults. Catapults launch aircraft into the air over short distances. An aircraft can be launched by a catapult every 2 minutes. The aircraft is positioned on the catapult, where it is prepared for 7 movement phases, then launched on the 8th phase. If the launch is aborted for any reason, the launch sequence must be restarted from the beginning. At the end of the launch phase, the aircraft will be moving at 25% of its maximum speed, at 100 meters altitude, into the wind. A carrier can only use one catapult per engagement turn. For example, if a carrier has 4 catapults and one aircraft is launched every 30 seconds (one engagement turn), the carrier will be able to launch 6 aircraft during a 3-minute tactical turn.

3.3.5.4.2 Free Takeoff. Fixed-wing aircraft that do not need a catapult to take off can be launched every 2 movement phases of an engagement turn. If catapults are located forward, they cannot be used, and no aircraft can land while an aircraft is taking off. At the end of the takeoff phase (either the first or the second movement phase), the aircraft will be moving at 25% of its maximum speed, at 100 meters altitude, into the wind.

3.3.5.4.3 Helipad. Helicopters and fixed-wing VTOL aircraft can take off vertically from helipads. A helicopter or fixed-wing VTOL aircraft can be launched from each spot every 3 minutes. If players are using engagement turns, at the end of the second movement phase, the aircraft will be moving at 25% of its maximum speed, at 100 meters altitude, into the wind.

Safe Sea State Table

Ships: carrier aircraft and helicopters can take off from or land on a ship safely in sea state 3 or less.

Sea surface: seaplanes, amphibious craft, and float-equipped helicopters can take off from or land on the water surface in sea state 2 or less.

Modifiers: sea state is modified under the following conditions (which are cumulative):

• If the ship has stabilizers: +1
• If the ship has dual stabilizers: +2 (Note: stabilizers only work if the ship's speed is at least 8 knots.)
• If the ship is medium size (126 to 400 damage points): +1
• If the ship is large size (401 damage points and up): +2
• If the ship has a recovery system (Bear Trap or RAST type — for helicopter landings only): +1

3.3.5.4.4 Takeoff from the Sea Surface. Seaplanes can take off from the sea surface. Takeoff requires 6 movement phases. The aircraft is prepared for 3 phases, then taxis on the water surface at 25% of its maximum speed, into the wind, for 3 movement phases. The aircraft then takes off at 100 meters altitude, at 25% of its maximum speed, at the end of the last phase. There is a 20% chance the seaplane crashes on takeoff for each sea-state level above 2 (the crash is automatic at sea state 7).

Float-equipped helicopters can take off from the sea surface. Takeoff requires two movement phases. At the end of the second phase, the helicopter will be flying at 25% of its maximum speed, at 100 meters altitude, into the wind.

3.3.5.5 Aircraft Landing. Aircraft wishing to land must be at low altitude and within one movement turn of the ship at the start of the movement phase during which they have planned to land. Aircraft can normally land safely on ships in sea state 3 or less. There is a 20% chance, per sea-state level above that, of the aircraft crashing onto the flight deck or helipad spot when it lands. The safe sea state can be increased by ship equipment or features listed in the safe sea state table.

3.3.5.5.1 Flight Deck. Flight decks fitted with arrestor wires will slow and hold fixed-wing aircraft landing on the deck. An aircraft can be recovered aboard a carrier once per minute, or at a rate of 3 per tactical turn. The aircraft must fly at 25% of its maximum speed toward the ship to land on it. Apart from use of the arrestor wire, only VTOL aircraft and helicopters can land on a ship.

3.3.5.5.2 Helipads. A helicopter or fixed-wing VTOL aircraft can land on one spot per phase. If the ship has a hangar for stowing the helicopter, the helicopter can be stowed there to allow another helicopter to land. It takes 5 movement phases of an engagement turn to stow a helicopter that has landed and prepare the helipad for another to land.

3.3.5.5.3 Sea Surface. Seaplanes can land on the sea surface. The seaplane must fly at 25% of its maximum speed and at an altitude of 100 meters, into the wind. After 4 movement phases of straight-line flight, the seaplane touches the water's surface and continues on for two more movement phases of an engagement turn. At the end of the second phase in contact with the water, the seaplane has landed. The safe sea state for landing on water is 2.

A float-equipped helicopter can land on the sea surface in one movement phase, or on the second movement phase if it was hovering during the previous phase.

3.3.5.6 Swamping. Any aircraft (seaplane or float-equipped helicopter) sitting on the sea surface has a 10% chance of being swamped in sea state above 3. The roll must be made on every tactical turn during which the aircraft is sitting on the water.

3.3.5.7 Ready Time. An aircraft must be readied for flight before it can take off. The Ready Times Table gives the readying time aircraft need before they can take off.

An armed aircraft is loaded with bombs or other equipment. An aircraft that is not armed (e.g. a Tu-95 Bear D) does not need this type of equipment. A fueled aircraft has its fuel tanks filled. An alert aircraft has had its pre-flight checks done and its crew briefed. A manned aircraft has its flight crew physically aboard and ready to operate the aircraft. Normally, aircraft are fueled, but unmanned, not on alert, and unarmed. A ready aircraft is armed (if needed), fueled, on alert, and manned; it is considered to be at +5 status (ready to take off in 5 minutes).

Arming, fueling and refueling, and alert operations can be carried out simultaneously. Any number of aircraft can be readied at any time, up to the limits of the support equipment.

3.3.6 Aircraft Range. The distance an aircraft can cover depends mainly on its payload, its speed, the altitude at which it flies, and its throttle setting. Aircraft fly most of the time at cruise speed, engines set to 75% of available maximum power. This speed lets them cover the maximum distance for the same amount of fuel burned. Adding equipment or flying at higher speeds will reduce the range, sometimes dramatically.

3.3.6.1 Aircraft Range. The maximum range for an aircraft flying at cruise speed is given in Annex B. This is based only on internal fuel capacity. Two things can be done to increase an aircraft's range:

• Carrying jettisonable external tanks. Annex B lists the number of jettisonable external tanks an aircraft can carry with each load-out. It also gives the additional range at cruise speed each tank provides. A jettisonable external tank also occupies a hardpoint, preventing any other equipment from being fitted to it.
• Aerial refueling. Many aircraft can be refueled in flight by tanker aircraft. A tanker aircraft may be an aircraft dedicated exclusively to aerial refueling, or an aircraft fitted with an external tank for "buddy refueling."

The tanker and the aircraft being refueled must have compatible equipment so that one can supply the other. Most aircraft use the probe-and-drogue method, in which a flexible hose fitted at its end with a basket-shaped drogue is reeled out by the tanker. The aircraft being refueled inserts its refueling probe into this drogue. Western (NATO and French) aircraft use one compatible standard, while Russian-designed aircraft use another.

The US Air Force also uses a different method called the "flying boom." This consists of a rigid, retractable pole (the "boom") deployed by the tanker and guided into the receiving aircraft's receptacle. This system was designed to refuel heavy bombers and transport aircraft and can transfer more fuel per minute than a hose. Only the KC-135 and the KC-10 use the flying boom and can refuel any US Air Force aircraft capable of being refueled in flight. The KC-135 can be fitted with an auxiliary drogue basket before takeoff if it needs to refuel probe-equipped aircraft. So equipped, it cannot use the flying boom method. The KC-10 carries a drogue basket and a flexible hose coiled in its fuselage in addition to the rigid retractable boom. See section 3.3.6.8 for the rules covering aerial refueling.

If an aircraft in flight runs out of fuel without having reached its base or a tanker, it crashes.

3.3.6.2 Effects of Ordnance and Altitude on Range. The payload carried by an aircraft will affect its range. The reduction in range depends on the load carried, expressed as a fraction of the aircraft's maximum payload, and on the other statistics listed in Annex B. This is all reflected on the Ordnance Performance Effect Table. There are two sets of tables, one for jet engines (single-flow turbojets or bypass turbofans) and another for all other engine types (turboprops, turboshafts, and piston engines).

The weight accounts for the total of pods, bombs, missiles, and other jettisonable ordnance, except for the internal gun, its ammunition, and jettisonable external tanks. Fuel from jettisonable external tanks is used to increase range, so it does not count as a penalty.

These load states are different from those used for air combat (section 6.3.1).

Each table entry expresses the same effect in different ways. A turbojet carrying 50% of its maximum payload ("Load 1") flying at high altitude will have its range reduced by 20%, or multiplied by 0.8 (.8). To find the range consumed while flying at a given altitude, divide the range covered at that altitude by the multiplier.

Example: an F-16, fitted with two 370-USG jettisonable external tanks, has a clean range at high altitude of 1,878 nm (1,100 nm of internal fuel plus 389 nm for each jettisonable external tank). If the aircraft carries a standard air-to-ground load of 8 Mk82 500lb bombs (241 kg each), 2 AIM-9M Sidewinders (85 kg each), and an ALQ-131 ECM pod (272 kg), the total load is 2,370 kg, or 43% of its maximum payload of 5,443 kg. This means that if it flies at high altitude, its range will be reduced by 20%. So, instead of a range of 1,878 nm, it will only be able to fly 1,502 nm. This is the data to base mission planning on.

After the F-16 has taken off to carry out its mission, its pilot is forced to dive to low altitude for several minutes to evade enemy aircraft. He flies at 450 knots for 12 minutes, covering 90 nm. To find how much cruise range this used up, divide 90 nm by 0.4 (reflecting a 60% reduction). The 12-minute detour cost the F-16 a total of 225 nm of range!

3.3.6.3 Effects of Throttle Setting on Range. All aircraft operate at 2 or 3 basic speeds, which depend on the throttle setting. They are said to fly at cruise speed, at full military power (FMP), or on afterburner. The exact speed in knots will vary with altitude and aircraft type. These are listed in Annex B for each aircraft. See also section 3.3.2.

Aircraft use up to one mile of range for each mile they cover at cruise speed. At a higher throttle setting, the distance covered must be multiplied by a factor based on the throttle setting and the engine type. The engine type (turbofan, turbojet, turboprop, turboshaft, or piston engine) is given in Annex B. These factors appear on the Endurance Modifier Table. It should be obvious that jet aircraft cannot stay on afterburner too long and must be careful when using full military power.

An aircraft can fly slower than the maximum speed corresponding to its throttle setting, but this yields no benefit in terms of range or endurance. For example, a Sea Harrier that can cruise at 450 knots can also cruise at 440 knots. This does not change the fuel consumption rate (in kg/nm), and the aircraft will burn the same amount of fuel to cover the same distance. If it flies at 460 knots, it must use full power, even if that speed is only a few knots above cruise speed at that altitude.

Example: a Sea Harrier (which uses a Pegasus turbofan engine) flies at its cruise speed of 450 knots for 10 minutes, covering 75 nm and thus using up 75 nm of its range. If it covered that same distance at its maximum speed, 650 knots, it would use much more fuel. Multiply the distance covered at cruise speed by the factor given for a turbofan aircraft at FMP (75 x 4.0 = 300). With a base range of 600 nm, this is a major reduction in its endurance.

3.3.6.4 Combining Altitude and Throttle Setting. Aircraft burn fuel most efficiently at their cruise speed at the most appropriate altitude. In the example in section 3.3.6.3, a Sea Harrier increases its throttle from cruise speed to FMP and suffers a 75% reduction in range. Does this mean an aircraft at low altitude at FMP will suffer a combined 90% reduction? No, because the drag and engine-efficiency effect (altitude change) is outweighed by the larger effect of the throttle-setting change.

If an aircraft changes altitude but stays at the same throttle setting, use the modifiers from section 3.3.6.2. If it changes throttle setting but stays at the same altitude, use the modifiers from section 3.3.6.3. If it changes both altitude and throttle setting, use the larger of the 2 reductions (which will always be the throttle-setting change).

3.3.6.5 Mission Planning. A mission profile must be developed for each combination of aircraft type, load carried, and objective.

1. Decide on the aircraft's mission and the load carried to accomplish it. Make sure the aircraft can carry this load by comparing it to the payload levels in Annex B. Calculate the load's weight as a percentage of the aircraft's maximum payload. You will use this in step 4.

2. Measure the distance from the aircraft's departure base to its objective, in nautical miles. This is the mission radius. Since the aircraft must fly to its objective and return, multiply this distance by 2 to get the total distance to be covered.

If the departure base is a moving carrier, the outbound heading to the objective and the return distance may be significantly different. Be sure to track the carrier's movement during the flight.

3. Choose the altitude at which the aircraft will fly to its objective. This will depend on the aircraft type and the type of mission assigned to it. The aircraft may fly at different altitudes for different segments of the mission. For example, a fighter-bomber may fly at cruise speed at high altitude for most of the trip, but will normally have to descend to low altitude as it nears the objective, to minimize radar detection for as long as possible.

Based on the range-reduction factor for the engine type, the altitude, and the load carried, calculate the distance to be covered for each segment of the aircraft's flight. This is the distance to be covered for each leg of the mission, and the total gives the overall range the aircraft will need to fly to its objective and back.

4. If the aircraft must fight, use full military power or afterburner for this. This will require extra fuel. For example, a turbofan-powered aircraft's cruise range might be 400 nm, but only 100 nm at full military power — equivalent to 9 minutes of combat at 650 knots, if it uses afterburner instead, equivalent to just one minute at 1,147 knots (Mach 2 at altitude) for 16 nm.

Choose how many minutes at full military power or afterburner you want to give the aircraft. The formulas are:

(Minutes at FMP/60) x cruise speed (knots) x FMP endurance modifier = distance to be covered at cruise-speed-equivalent

(Minutes on afterburner/60) x cruise speed (knots) x afterburner endurance modifier = distance to be covered at cruise-speed-equivalent

(This procedure is refined in the 5th edition of Harpoon.) This "combat margin" is added to the mission's distance to be covered.

5. Compare the mission's total distance to be covered with the base range given in Annex B. The base range corresponds to the amount of fuel carried in the aircraft's internal tanks. If the aircraft's base range exceeds the mission's distance to be covered, then the flight can proceed on internal fuel alone.

6. Good planning allows a 10 to 15% reserve above what the mission requires, to account for unforeseen circumstances — for example, if the objective has moved further away, if evasive action must be taken, or if the objective must be changed after the aircraft has taken off. Nothing is more frustrating than having to turn back a short distance from the objective for lack of fuel. This means that for a mission requiring 1,000 nm, the aircraft should have fuel to cover 1,100 nm. Increase the mission's distance to be covered by 10%, or by whatever factor you choose.

7. If the base range is less than the mission's distance to be covered, then add jettisonable external tanks. Single external tanks are carried under the fuselage, while pairs are carried with one tank under each wing. Annex B lists the various equipment load-outs, including jettisonable external tanks, and the increase in cruise-speed range provided by each external tank carried. Jettisonable external tanks do not affect the aircraft's load level for range calculations, since their fuel is burned first. Add the range provided by each external tank carried to the aircraft's base range.

If the resulting increased range is sufficient, the mission can be flown. If the resulting increased range is not sufficient, you must either abandon the mission or plan for aerial refueling. Aerial refueling may be planned in addition to external tanks.

Example 1: An A-6E Intruder (fitted with a turbojet engine) is assigned a strike against an objective using 4 Mk84 bombs. At 894 kg each, the 4 bombs require 43% of the Intruder's maximum payload of 8,165 kg (step 1). The objective is 500 nm away. The distance to be covered is therefore 1,000 nm (step 2).

The aircraft will fly to the objective at cruise speed at high altitude, and will return the same way. But the aircraft will need to approach the objective at low altitude for a 100 nm segment. The mission's 3 segments are: 400 nm at high altitude, 100 nm at low altitude, and 500 nm again at high altitude. Note that on the return leg, the aircraft will be "clean," since it will have dropped its entire load. Using the 43%-payload reduction factor for a turbojet aircraft, the actual distance to be covered will be (400/0.8) + (100/0.4) + (500) = 500 + 250 + 500 = 1,250 nm (step 3).

The player decides to add 10 minutes of low-altitude combat. Using the low-altitude cruise speed of 400 knots, (10/60) x 400 x 3.5 = 233 nm of extra cruise-equivalent distance to be covered. The total distance to be covered is 1,250 + 233 nm = 1,483 nm (step 4).

The base range for an A-6E Intruder is 1,600 nm. It therefore has enough range to reach the objective on internal fuel alone (step 6), but if an additional 10% reserve is added, the mission's distance to be covered becomes 1,483 x 110%, or 1,631 nm. This distance exceeds 1,600 nm, and since the player still has a free hardpoint, he can add one 300 USG jettisonable external tank, increasing the aircraft's range by 201 nm, to a total of 1,801 nm.

Example 2: An F/A-18E Hornet must escort an A-6E on a strike against an objective 500 nm away. The distance to be covered is therefore 1,000 nm. It carries 4 AIM-120 AMRAAMs (152 kg each) and 2 AIM-9M Sidewinders (85 kg each). This brings its total load to 778 kg, or 10% of its maximum payload (steps 1 and 2).

The mission will be flown entirely at high altitude, so the endurance modifier for a turbofan aircraft with a "clean" load (0 to 15% of max) is 1.0, i.e. no reduction (step 3).

Since the purpose of an escort mission is to engage hostile aircraft, the mission planners want to add 10 minutes at full military power and 2 minutes of afterburner, all at high altitude. Its high-altitude cruise speed is 490 knots. The formulas are:

(10/60) x 490 x 4.0 = 327 nm for 10 minutes at full military power.

(2/60) x 490 x 24 = 392 nm for 2 minutes of afterburner.

Added to the initial 1,000 nm distance to be covered, these bring the mission's distance to be covered to 1,719 nm (step 4). Adding a 10% reserve brings it to 1,891 nm.

Compared to the F/A-18E's range on internal fuel (1,600 nm), this falls short by 291 nm. However, the aircraft has enough free hardpoints to carry 2 jettisonable 330 USG external tanks, each adding 188 nm of extra range. The combined total of 1,976 nm is enough to reach the objective.

3.3.6.6 Mission Planning for Aircraft Formations. A group of aircraft uses the takeoff time of the first aircraft to determine its endurance. The first aircraft will have to orbit until the rest of the formation joins it, and will be the one that burns the most fuel (at cruise endurance).

Example: the A-6E leader of a 20-aircraft group takes off from a carrier and climbs to wait for the rest of the aircraft to take off. A carrier with 4 catapults can launch one aircraft every engagement turn (see section 3.3.5.4.1). It will take 20 engagement turns, or 10 minutes, to launch them all. The leader will therefore wait at high altitude for 10 minutes, using up 10 minutes' worth of cruise endurance.

3.3.6.7 Game Considerations. The referee (if there is one) can help players plan their flights and can check their calculations. Ultimately, players are responsible for their aircraft running out of fuel.

Aviators tend to be very cautious, and will not continue the mission once the "bingo" fuel limit is reached. The "bingo" fuel limit is the amount of fuel needed to get home, plus reserves. If the aircraft is engaged in air-to-air combat, it will try to disengage once the bingo point is reached.

If an aircraft returns to its departure base and a calculation error is later discovered showing that the aircraft should have crashed from fuel exhaustion, assume that it benefited from a tailwind that miraculously saved it. Be wary of players who benefit from recurring tailwinds.

3.3.6.8 Aerial Refueling. Annex B indicates whether an aircraft can be refueled in flight. It also indicates whether an aircraft can refuel another aircraft. If the "Y" or "N" is followed by a slash and a number, that number indicates how many small aircraft can be refueled simultaneously. The entry for the Victor K.2 is "Y/2." This means the Victor can be refueled (Y) and that it can refuel two small aircraft simultaneously.

Aircraft size (Large, Medium, or Small) is given in Annex B. A tanker that can refuel an aircraft can do so regardless of its size. If it can refuel 2 or 3 Small or Medium aircraft, it can instead refuel one Large aircraft. A buddy tank can only refuel one aircraft at a time.

To refuel another aircraft, the tanker must fly at its cruise speed. Each aircraft to be refueled matches its location, altitude, speed, and heading with the tanker.

A tanker can transfer as much fuel as it wishes to another aircraft. To calculate how much fuel the tanker can deliver:

1. Determine the distance the tanker still has to fly to get home, and subtract that amount of fuel (marked up, as usual, by a 10% reserve) from the tanker's remaining range. If the tanker is 700 nm from its base and has 1,700 nm of range remaining, it can deliver 930 nm of fuel (1,700 − (700 x 1.1)). This is the "deliverable range."

2. Calculate how many kg of fuel each aircraft involved in the refueling uses to fly 1 nm, by dividing its internal tank fuel by its range (on internal tank fuel alone).

3. Divide the "deliverable range" by the tanker aircraft's kg/nm ratio. This is the actual weight of fuel that can be transferred.

4. Determine how long the fuel transfer will take using the "Inflight Refuel Transfer Table": divide the fuel to be transferred by the kg/tactical turn rate to determine how long it takes to transfer the fuel to the other aircraft. Add 1D6 tactical turns to this time to simulate the time needed to hook up.

5. Finally, divide the transferred fuel by the receiving aircraft's kg/nm ratio to find its gain in cruise endurance.

In short: (tanker's range x tanker's kg/nm) / (kg/nm of the refueled aircraft) = range gained by the refueled aircraft.

Example: a Tu-22M Backfire needs to refuel over the Norwegian Sea. The tanker, an Il-78 Midas, has a cruise range of 6,274 nm. It has already burned 1,000 nm and needs 1,000 nm more (plus a 10% reserve, i.e. 100 nm) to get home, so it can transfer 4,174 nm of endurance to another aircraft. The Midas burns fuel at a rate of 65,340 kg/6,274 nm, or 10.4 kg/nm. The 4,174 nm of endurance represents 43,410 kg of fuel. Using the probe-and-drogue method, this will take 12 tactical turns (always rounded up), or a bit over half an hour, to transfer all the fuel.

The Tu-22M Backfire, carrying 2 AS-4s, has flown about 1,000 nm, but has already burned 1,000/0.8, or 1,250 nm, of cruise range. Since a Backfire burns 50,000 kg of fuel / 5,940 nm = 8.4 kg of fuel per nm, it needs to be delivered 10,500 kg of fuel by the tanker. This will take it 3 tactical turns, or 9 minutes. The Midas can currently fill up 4 Backfires at 1,000 nm from base.

A tanker cannot deliver more fuel than it has, and an aircraft cannot receive more fuel than its capacity allows.

If a game involves aerial refueling, the players and the referee can precalculate the amounts needed, and in most cases the refueling will take place without incident.

3.3.6.9 HIFR (Helicopter In-Flight Refueling). This operation can be carried out between any NATO ship and a helicopter. The helicopter approaches the ship and hovers over the aft helipad. The ship steams with the wind 30° off its starboard bow. The combined speed of the ship and the wind must equal 30 knots. The helicopter descends and aligns with the deck, and the crew attaches a fuel hose to it. The hose is winched up to the helicopter and connected to the fuel system. After 1D6+5 minutes, which includes hookup and disconnection, the helicopter is refueled. It drops the fuel hose onto the deck, then continues its mission. The ship does not need a helipad or other aviation facilities to perform this operation; it only needs a fuel-replenishment system. This method also lets a large helicopter be refueled from the deck of a small ship.

3.4 Missile Movement

From the moment a missile is launched, it flies toward its target in accordance with the information from its guidance system. Since a missile is launched during a turn's fire phase, it cannot move until the next movement phase. If the missile must interact with other units, it covers half its movement during the first movement phase and the other half during the second movement phase of the Engagement Turn.

Example: a P-15 Termit [SS-N-2A Styx], with a speed of 516 knots, is launched during the planned fire phase of turn 1000. During the movement phase of the Tactical Turn (1003), it moves 25.8 nm. If it closes on its target and the players switch to Engagement Turns, it will move 2.2 nm in the first phase and another 2.2 nm in the second movement phase.

Surface-to-surface and surface-to-air missiles are described in Annex D. Air-to-air missiles are in Annex H, and air-to-surface missiles in Annex G.

Missile counters may be used to represent missiles in flight. A group of missiles launched at the same time may be represented by a single counter. This speeds up the game and avoids alerting the other side to the nature and size of the salvo.

Missiles fired during the planned fire phase are not valid targets during the next reaction fire phase. Although they have been launched, they have not yet cleared the ship, and as a result no weapon will be able to distinguish them from their launch platform — even though submerged missile launches do break the water's surface during their launch phase.

3.4.1 Speed. Missiles fly at their maximum speed for the entire flight.

3.4.2 Course Change. Missiles have an unlimited ability to change course as long as they are guided toward their objective. The missile's guidance system determines how much it can maneuver to pursue its target. Sections 5.3 and 5.4 describe the various types of missile guidance systems.

3.4.3 Altitude Change. Missiles will change altitude as they head toward their targets or as they pursue them.

Surface-to-air missiles (SAM) can change altitude level an unlimited number of times during an engagement turn.

Surface-to-surface and air-to-surface missile (SSM and ASM) flight paths will follow either a ballistic profile or a cruise profile. A ballistic profile means the missile follows an arc from the launching unit to its target. If launched from a ship, it will climb to the maximum altitude given in Annexes D or G4, then descend as it approaches the target. It will be at maximum altitude halfway between the launching ship and the objective. ASMs with a ballistic profile will only descend, after launch, during their final approach to the objective. Missiles with ballistic profiles never descend to very low altitude (V low). They launch their attacks from low altitude.

Cruise missiles will climb to their maximum altitude on the turn of launch, then descend to their indicated minimum altitude and remain there for the entire flight. Depending on their type, they may nonetheless perform a final maneuver.

3.4.4 Missile Range. Each missile type has a maximum range given in Annex D. When a missile reaches its limit, it runs out of fuel and crashes into the sea. If an air-to-surface missile is launched from low altitude and has a ballistic trajectory, its range is halved.

If an air-to-air missile is fired from low altitude or from behind the "90° line," for example from behind a bomber, its range is halved. At low altitude AND fired from the rear, range is reduced to a quarter.

Missiles with an SARH guidance system have their range increased by 50% against closing targets that are not maneuvering.

3.4.5 Delayed Impact. Missiles or aircraft attacking surface targets will need to switch to Engagement Turns to resolve the attacks. An air unit launches its attack against a ship during the movement phase of the Engagement Turn in which it reaches its target. This may be a missile, an aircraft making a bombing, strafing, or any type of unguided-weapon run. The target may be able to defend against this type of attack. In most cases, the ongoing attack cannot be resolved as long as the ship still has a chance to fire.

Many units are fast enough to cross all of a ship's defenses and attack it within a single movement phase. An aircraft or missile moving at 600 knots moves 2.5 nm per Engagement Turn movement phase and will pass straight through the detection envelope of a Mk15 Phalanx, which has a range of 0.8 nm (1,600 yards).

An air unit attacking a ship must stop next to it so that all weapons still available for the ship's defense can open fire. After these weapons have fired, the ongoing attack will be resolved during the next resolution phase.

This is not a "free shot" for the defender, but a special rule to work around the artifices of turn-based movement. It is a temporary suspension of the air unit's movement so that all weapons entitled to fire can do so. Autonomous systems are able to fire during both the first and second fire phases of an Engagement Turn, but they are the only ones that can do so.

An air unit cannot be attacked by a surface-to-air missile that has a minimum range during the turn it reaches the ship, because that unit has already crossed the minimum-range threshold during that turn. Ranges are measured at the instant of the surface-to-air missile's launch. This means it happens after the movement phase, when the distance is officially 0.

If no anti-aircraft weapon is available, the attack can be resolved immediately, during the movement phase in which the air unit reaches its target.

3.4.6 Evasive Maneuvers. Because they are much faster than ships, anti-ship missiles are not affected by their target's maneuvers.

3.4.7 Waypoints. Certain inertially-guided missiles can be programmed at launch to change course at precise locations. These are called "waypoints." They let missiles attack from unexpected directions or bypass known obstacles.

If a missile has waypoint navigation capability, this information will be given in the corresponding Annex, in the "Remarks" column. Before launch, the player controlling the missile must specify the various geographic points where the missile will change course, as well as the angle it will take, which can be up to 90° in any direction.

In this kind of case, a ship uses a missile with waypoint capability to conceal itself behind terrain, as much as to disguise the direction the attack is coming from.

3.5 Torpedo Movement

Once launched, torpedoes move toward their objective in accordance with their guidance system's parameters. Counters may be used to track torpedoes along their path to their objective. Torpedoes are described in Annex F.

3.5.1 Speed and Range. Some torpedoes have two or more speeds per Annex F, with corresponding ranges. Speed may be selected at the moment of launch. If the torpedo is wire-guided, its speed can be changed by command from the launching platform. The torpedo will then use the corresponding range.

If a dual-speed torpedo acquires a target, it will automatically accelerate to the higher of the two speeds.

When launched during the planned fire phase, torpedoes move the full distance allowed by their speed during the next movement phase. When launched during the reaction fire phase, they only move half that distance during the next movement phase, then the full distance during subsequent phases.

When a torpedo reaches its maximum range, it stops and sinks without exploding.

3.5.2 Course Change. There is no limit to the turns a homing torpedo can make toward its objective.

3.5.3 Depth Change. Torpedoes can be launched at any depth against a target at any depth. They will change depth as much as needed to intercept the target.

3.6 Collisions and Ramming

When two ships are not engaged in a towing operation or underway replenishment, and pass within 500 yards (0.25 nm) of each other, there is a risk of collision. Every time a submarine surfaces or rises to periscope depth (whether or not it uses its periscope or snorkel), there is a risk of collision with a surface ship. Two submerged submarines have no collision risk as long as they are not at the same depth. Unless they are attacking a ship, aircraft at very low altitude also risk colliding with ships when they are within 500 yards of them.

3.6.1 Resolution. When there is a collision risk, roll a D6 and refer to the collision table. Apply the modifiers, and if the result is a 6, there is a collision. Both ships are dead in the water (speed zero).

3.6.2 Damage. When a collision occurs, each ship inflicts damage on the other based on its size. A large ship inflicts more damage on the other vessel than a small ship does.

Roll 1D6 for each ship and consult the right-hand column of the collision table. Each player takes the resulting percentage and multiplies it by his own ship's original damage-point total. The result is the number of damage points he inflicts on the other ship.

If the result is a critical hit, damage is determined by a roll on the "Torpedoes vs. Surface Ships" column of the Critical Hit Types table in section 7.3. Damage results apply immediately (i.e., during the movement phase).

Aircraft that collide with ships are destroyed. The ship takes damage points equal to 2D6 x the number of engines the aircraft has. The aircraft automatically causes a fire critical hit. Any ordnance carried by the aircraft does not detonate. Aviation ordnance does not explode until it has been dropped.

Collision probability die-roll modifiers. The modifiers on this table are cumulative:

• Per small ship involved: −1
• Per large ship involved: +1
• Per ship deliberately attempting to ram: +2
• If a critical hit/bridge and an attempt to ram: −1
• If a critical hit/bridge and an attempt to evade (cannot evade normally): +1
• If a ship attempts to ram a stationary ship: +3

Collision damage die-roll modifiers:

A ship that rams bow-first (with a perpendicular impact within 30°) has the damage it suffers halved. An oblique impact (at an angle of 30° or less between the ships' headings) halves both ships' damage.

Add 1% to both ships' damage percentage for each knot of relative speed. To determine relative speed, add the 2 speeds if the two bows are facing each other, subtract the slower speed from the faster if the bows share the same heading, and use the greater of the 2 speeds if it is a bow ramming.

Standing Orders. Standing orders are not only an integral part of naval command, they are also the best way to speed up the game. With both sides' standing orders in place, players can plan their movements over long periods and speed up the approach to battle.

Standing orders are orders that remain in effect until further notice or until they expire. Every captain gives standing night orders to the officer of the deck before retiring for the night. ("Eternal vigilance is the price of safety.") A good admiral will give his standing orders before the battle, explaining to his captains what he has planned.

For example, a side conducting a security patrol might give the following standing orders: "Ships will patrol a 20 nm loop on a NW/SE heading at 15 knots until they detect an enemy. All detectors passive." The other side might order: "Ships will steam in 2 columns on a course of 090° at 20 knots, zigzagging 30° either side of their base course every 20 minutes. Continue this movement until 0900. Air-search radars will emit once per 10-minute period (at random intervals). All other detectors passive." Orders can be more complex, involving both aircraft and ships, developing attack or search plans.

Example: the USS Knox manages to ram a Krivak III-class frigate on her flank. This will be a bow ramming for the US ship. Their relative speed is 15 knots. The Knox's damage-point value is 96; the Krivak's is 107. The Knox player rolls 1D6 and gets a 2, or 15%. The Krivak player rolls 1D6 and gets a 4, or 25%. The Knox inflicts 15% + 15% (for speed) of 96, or 29 damage points, on the Krivak. The Russian ship inflicts 25% + 15% (for speed) of 107 points, or 43 points, halved because the Knox rammed bow-first (22 damage points).

3.7 Units Arriving in the Battle Area

Units may exist outside the battle area and arrive during the battle or scenario. In general, such units take part in the battle once they come within the maximum detection range of any other unit currently in the battle area.

Given the distances involved, the distance at which a unit arrives does not by itself justify placing it on the playing surface. Players must have knowledge of the unit's existence for that. However, once detection equipment has detected that unit, it will be placed on the playing surface.

Units too far away to be placed, but which have been detected, may be reported to players in terms of position, altitude, heading, and speed.

Example: An SS-N-3 Shaddock is fired at maximum range (250 nm) against USS Decatur (DDG). The Decatur's SPS-29 air-search radar has a range of 108 nm against small targets. The missile is placed on the playing surface 108 nm from the Decatur. In fact, the missile can be noted as appearing at that distance, then as moving the appropriate distance on paper each turn, until it reaches a manageable distance (in terms of the playing surface). Alternatively, with a large enough room and a good scale, a counter can be placed on the playing surface directly.

By writing out these orders, players are forced to think deeply about their battle plan. They can take everything into account: where would they most like to encounter the enemy? What should they do with their aircraft? Is there a submarine threat? What heading should they follow? Have they accounted for the effects of the environment on movement and detection? By writing their orders independently, players can cooperate in planning the movement of their forces, seeing where and which of their units will encounter each other. This information can be used to set up the battle. An alternative is to give the orders to a referee, who will interpret and execute them, reporting back to the appropriate commanders the results of their respective detections. If there are several players on one side, and one of them has been designated commander, he can issue standing orders determining what the others should do in the event of an attack, how they should maneuver, and how to accomplish their mission. A little advance planning will increase both the speed of play and the quality of the game.

Chapter Four – Detection

4.1 Detection System Basics

Detection systems have grown in capability and diversity since World War II. A typical modern destroyer receives information from its lookouts and electro-optical (visual) detectors, from 2 or 3 kinds of search radars, from at least 1 sonar, and from electronic intercept equipment (ESM). The ship's helicopter can also supply information from its sonobuoys, its MAD (magnetic anomaly detector), and its radar. Some helicopters are fitted with a dipping sonar. Thanks to modern communication capabilities, information supplied by one unit's detection systems is known to every other unit in communication with it during the same tactical turn.

4.1.1 Detection System Media. Detection systems use the electromagnetic, magnetic, and acoustic spectra to gather information. Without going too deeply into information science, energy must pass from the potential contact to the detecting platform for information to be exchanged. This can be heat (infrared, within the electromagnetic spectrum) given off by a jet engine, or the noise of a ship's propellers (kinetic energy radiated into the water as sound waves). It can also be visual contact, resulting from light energy (also within the electromagnetic spectrum) reflecting from the contact to the observer.

The most important requirement for a detection system is that the energy passing through the environment be readily detectable. For example, sound travels much faster through water than through air, which makes it a good basis for submarine detection. Neutrinos are given off by atomic reactions and travel great distances without any resistance. They could be used to detect nuclear-powered ships, except that the detector would require a tank of 30,000 gallons of coolant fluid!

Detection Systems

Medium	Type	Mode	Information Provided
Radio waves	Radar	Active	Bearing, range
	ESM, RWR	Passive	Bearing, emitter type
Visible light	Lookout, laser	Passive	Bearing, range, type (ID)
	RF	Active	Bearing, range
Heat	IRST	Passive	Bearing
	FLIR	Passive	Bearing, type (ID)
Magnetic force	MAD	Passive	Presence within detection range
Sound waves	Sonar	Passive	Bearing, type (ID)
	Sonar	Active	Bearing, range

4.1.2 Sharing Detection System Information. For game purposes, information about a target's location obtained during the detection phase is instantly known to all units on that side as of that detection phase. In the real world, the data would have taken a few milliseconds to transfer (via digital data links), a brief instant (via radio waves), or would not have been transferred at all (to a submerged submarine, for example). Information sharing is an important part of modern naval warfare.

Example 1: 2 ships each obtain an ESM contact (bearing line only) on an enemy ship. Although neither knows precisely where the hostile unit is, by comparing bearings they can triangulate its position and have enough data to launch a missile.

Example 2: a helicopter fitted with a surface-search radar (many are) can be sent ahead as a scout to detect other surface ships. When a target is located by the helicopter's radar, it can relay the contact's position to the rest of the force, which can then launch its missiles.

4.1.3 Active and Passive Detection Systems. A passive detection system is one that detects energy (such as heat or sound) given off by a contact. This system will give direction (bearing), but not range (for example, try to tell the distance of a sound you hear). An active detection system radiates energy, which is then reflected by the target and returns to the detection system. Radar is one example, as is a light at night, although the human eye cannot measure the distance. Active detection systems give both direction (bearing) and range for any contact, but at a cost. Since the detection system radiates energy, it can itself be detected, which will reveal the ship's location and give information about its nature. For example, a merchant ship would probably not use active sonar.

4.2 Radars

Radars send pulses of radio waves into the air. Objects in their path reflect them back to the antenna, whose direction gives the bearing, and the wave's return time gives the range.

4.2.1 Radar Characteristics. Radars are listed in "Annex J" for ships and submarines and in "Annex L" for aircraft. Some cannot see surface units; others can even give the size of an air unit. The type column, which describes its function and what kind of contact it can see, is covered in detail in sections 4.2.3 and 4.2.4.

4.2.2 Radar Detection. Within their detection zone, the chance of discovery is 90% in a Tactical Turn and 60% in an Engagement Turn. Radar detection during an intermediate turn is automatic (100%). The die roll is made during the detection phase. If it fails, the player may try again next turn, as long as the potential target remains within detection range. Once detected, players no longer need to roll again to detect it. It remains visible until the radar is damaged, shut off, or the contact leaves the detection zone.

4.2.2.1 Contact Size. The bigger the contact, the farther away the radar can detect it. Harpoon 4 uses 5 radar signature sizes, creating 5 detection ranges for each radar.

The French DRBV22 and the American SPS-48 are both air-search radars of roughly the same order of magnitude. The SPS-48 has a longer range against large targets because of its electronic characteristics (more powerful, larger antenna) and a better computer. When checking a radar's detection range, refer to Annexes A and B for ships and aircraft, then check the radar's annex for the ranges at the given size. Aircraft and ships have their size classes described in section 2.3.

Radar signatures can be altered. Ships and aircraft that use blip enhancers (6.7.2) are detected as one size class larger. Ships or aircraft can have an RCS smaller than their actual size, due to their physical design. But if a "very small" or "stealth" RCS unit is carrying an external load, its signature moves up to "small."

Submarine periscopes and other masts have very small or stealth size classes. Stealth masts and periscopes will be noted in the remarks section of Annex A. If 2 or more masts are raised simultaneously, treat them as a small-size target.

4.2.2.2 Radar Line of Sight. The maximum distance at which one unit can detect another is limited by the distance to the horizon. This depends on the units' height and the detection method used — visible light, infrared, or high-frequency electromagnetic energy (radar and ESM). Visible light and radio waves are both refracted by the Earth's atmosphere, though visible light is refracted less than radio and radar waves.

To find the maximum line of sight, consult the "Radar Line of Sight Table." For example, a large ship with a DRBV 23 air-search radar attempts to detect a bomber flying at medium altitude. The radar has a range of 160 nm against large targets (cf. Annex J1). Referring to the "Radar Line of Sight Table," find the searching ship's class in the left-hand column (large ship), and cross-reference it with the aircraft column (at medium altitude). At the intersection, we find 110 nm. This is the maximum detection distance for a large ship against an aircraft flying at medium altitude, regardless of the radar's actual power. If the same ship tries to detect a medium-size aircraft, the distance will then be 99 nm (cf. Annex J1), which is comfortably within radar line-of-sight distance. So, if the pilot wants to avoid being spotted, he will need to fly at low altitude, which will lower the line of sight to 53 nm.

4.2.2.3 Radar Information. Most radars show only a "blip," a point of light on a screen. A detection will automatically show the contact's range and bearing. If the player manages to get multiple detections over a minimum of 2 minutes, he can deduce the contact's course and speed.

Normally, it is impossible to identify a contact from a radar echo alone. Other detectors, such as ESM or passive sonar, can help classify it, or it can be inferred from other contact movements. Some radars are capable of imaging and classifying a target. They use SAR (Synthetic Aperture Radar) and ISAR (Inverse Synthetic Aperture Radar) technologies. These radars use special electronic techniques and computer processing to display a raw image of the target. SAR and ISAR radars have sometimes been used for reconnaissance, but the processing required kept their images from being visible immediately. Now, with improved computer processing power, their images are visible in real time and can be used tactically. Detected aircraft and ships can be classified by type or class, and land targets are identified. SAR and ISAR radars are identified in the "remarks" column of Annexes J and L.

4.2.2.4 Automatic Detection (optional rule). If both sides agree, any group of 3 or more units fitted with a given type of search radar (e.g. surface search) will detect all eligible contacts for that radar type. The contact will be detected at the shortest of these radars' ranges. The detecting player may choose which 3 radars he will use (if more than three radars are powered up). This rule may not be used when attempting to detect submarine periscopes or radar masts.

For example, 3 ships have a total of 3 powered-up air-search radars with maximum detection ranges of 270, 200, and 180 miles. All eligible air contacts will be automatically detected at 180 miles, subject to line-of-sight limitations. This rule speeds up the game by removing the detection phase for certain detection systems. If several ships use their radars interoperably and maintain communications, the probability that a contact remains undetected will be very low.

4.2.3 Naval Radars. Naval radar characteristics are listed in Annex J, sorted by type. Some radars have more than one function. These are called "multifunction radars" and can operate in several modes simultaneously, and their detection covers all of them. There are several types of naval radars, each with different functions and capabilities.

4.2.3.1 Surface Search Radar (SS). Surface-search radars are medium-range radars that only detect ships and land contacts, or aircraft flying at very low altitude (0 to 30 meters). They are sometimes called navigation radars.

4.2.3.2 Air Search Radar (AS). Air-search radars locate aircraft and missiles flying at low altitude and above; they have a range of several hundred miles. They can also detect very-low-altitude targets, as well as surface contacts, at 5% of their maximum range. If a radar is combined SS and AS, it can detect surface targets out to the radar horizon.

4.2.3.3 Height-Finding Radar (HF). Height-finding radars are not search radars; they are used to find a contact's altitude after it has been detected by an AS radar. Long-range surface-to-air missile systems need altitude data in order to be fired. This radar type will be noted on the missile system's lines in Annex A. If the radar contact is lost, the surface-to-air missile cannot fire.

A height-finding radar can find a contact at any altitude; it is only limited by the radar's maximum range and by the radar horizon.

4.2.3.4 Three-Dimensional Radar (3D). These are air-search radars that use advanced techniques to find a contact's altitude. They combine the functions and capabilities of an SS radar and an HF radar. Long-range surface-to-air missiles need a 3D radar to function. This radar type will be noted both on the missile system's lines in Annex A and among the ship's detection systems. If a 3D radar is lost, the associated surface-to-air missile system can no longer fire.

4.2.3.5 Periscope Radar. A specialized radar type is the periscope radar, whether on a retractable mast or built into the periscope of a submarine.

Radar Cross Section (RCS) and Stealth. All ships, aircraft, and other objects have a radar cross section (RCS), measured in square meters. Most often described as an object's radar signature area, it is more accurate to define it as radar reflectivity, which has little to do with the extent of its actual physical surface.

Since a radar's detection range is directly affected by RCS, it is best to have as small an RCS as possible. Radar waves do strange things when they strike a surface, especially a metal surface. They are, of course, reflected by smooth surfaces, but a seam between two pieces of metal only a few millimeters wide can be wide enough to act as a corner reflector, which focuses and amplifies the echo. Engine intakes, with their jumble of metal parts and compressor blades, are notorious radar traps. The aircraft cockpit is another, with the radar wave passing through the canopy, bouncing around inside, and scattering back out again.

By improving tolerances and surfaces, using substitute materials, and adding a number of small improvements, an aircraft's RCS can be reduced at modest cost. For example, adding a transparent gold conductive film to the windscreen (look at a good color photo of an F-16) makes it opaque to radar and considerably reduces the frontal radar return.

Making a platform fully stealthy requires special shapes and materials. Engine inlets and exhausts can be concealed, surfaces must form angles, and surface positions must be controlled so that they do not form right angles, or "corner reflectors." Radar-Absorbent Materials (RAM) are an exotic alloy of a ceramic- or resin-based component with a metallic component that absorbs and scatters the radar wave as it passes through. RAM can be used as a surface coating, it can be used to line an intake to reduce internal reflections, and in many other ways to reduce the reflection of radar energy.

Radar cross section depends on the platform's angle relative to the radar wave and on the characteristics of that wave, especially its polarization and frequency. This means that an aircraft optimized to have a low RCS against low-frequency search radars will not be as stealthy against high-frequency weapons radars. It also means that an aircraft that is stealthy from one angle may not be stealthy from another. Making a platform stealthy against all radars and from all angles can be very costly. Hence the enormous costs of the F-117 and the B-2.

It is more reasonable to take the relatively inexpensive first step and build a platform that is hard to observe rather than fully stealthy. The designers of the Rafale, the Eurofighter 2000, and other modern aircraft chose this approach. Other aircraft, such as the F-22 and the RAH-66 Comanche, are genuinely stealthy, and their cost reflects it.

Stealth applies to ships as well as aircraft. Many modern ships have sloped sides and a RAM coating to reduce their RCS. One of the first ships with such features was the Russian Kirov class, which many sources report had the signature of a frigate.

A periscope radar assists a modern submarine in gathering targeting information for its anti-ship weapons. It requires the submarine using it to be at periscope depth with its radar mast or periscope raised.

4.2.3.6 LPI Radar. Low Probability of Intercept is a feature that greatly reduces the chances of being detected by ESM. Although only a small number of radars have this feature today, it will become more common over the next decade.

ESM range is reduced by 75% against an LPI radar. For example, a patrol boat fitted with an LPI radar has a detection range of 14 nm against a frigate. If the frigate has a 3rd-generation ESM system (horizon range x 1.5, see section 4.3), it can detect a normal radar at 19 x 1.5, or 28.5 nm. It will detect an LPI radar at a quarter of that distance, i.e. 7.1 nm, which is less than the radar's own detection range. LPI radars are identified in the remarks column of Annex J.

4.2.4 Aircraft Radars. Most aircraft carry a combined search and fire-control radar in their nose. A minority of aircraft are fitted with a dedicated search radar with no fire-control capability (e.g. the E-2C Hawkeye with the APS-125), and another minority are fitted only with a ranging radar with no search capability. Aircraft radar functions are listed in Annex L.

Most aircraft have a 120° arc centered on the nose. A minority, like the APS-125, have a 360° arc. This information is given in the remarks section of Annex L.

4.2.4.1 Aircraft Surface Search Radar (SS). Some aircraft are fitted with surface-search radars. These radars detect surface and very-low-altitude contacts at the shorter of two ranges: line of sight or the radar's maximum range. Aside from the line-of-sight effect, detection capability is not affected by altitude.

4.2.4.2 Aircraft Air Search Radar (AS). These radars detect air units at the specified ranges at their own altitude level and at the 2 levels above and 2 levels below. They operate at half range against contacts located two levels above or one level below them.

4.2.4.3 Airborne Interception Radar (AI). These radars combine the functions of air-search and surface-search radars. They also feed information to the aircraft's fire-control system.

Some AI radars can detect air contacts at full range at 2 altitude levels above and 2 altitude levels below the aircraft's own altitude level. These are called LD/SD (Look Down/Shoot Down) radars in the type column of Annex L.

4.2.4.4 Range-Only Radar (RO). Some aircraft are fitted with very simple ranging radars, which give the range to a known target located directly ahead of the aircraft's nose. They have no search capability, and only feed information to the fire-control computer. Ranging radars are identified by the abbreviation RO in Annex L.

4.2.4.5 Terrain-Following Radar (TF). These are specialized radars that let an aircraft fly at nap of earth without restriction (see section 3.3.4.1), regardless of weather or time of day or night.

4.2.5 Environmental Effects on Radar. Despite its ability to see through darkness and storms, radar's capability is reduced by waves and nearby land masses.

4.2.5.1 Sea State Effects. The probability of detecting contacts on the sea surface and at very low altitude is reduced when the sea is rough. This is because the radar beam strikes the top of the wave and is reflected there. The larger the waves, the more clutter appears on the radar screen. Larger waves also cause the ship to pitch and roll, raising and changing the angle of the antenna.

Sea state effect modifiers:

• If the ship has stabilizers: −1 on sea state
• If the ship is large: −1 on sea state
• Very small contact at very low altitude, sea state 5 and up: −10% chance of detection
• Stealth contact at very low altitude, sea state 5 and up: −20% chance of detection

Submarine periscopes and masts cannot be detected by radar from sea state 4 upward.

Example: HMS Sheffield attempts to detect an inbound AM.39 Exocet with her Type 1006 radar. Sea state is 7. The radar's base detection probability is 90% in a tactical turn. Sheffield is not large enough (small size class) to benefit from ship-size reductions, but she is fitted with stabilizers (−1). The effective sea state is now 6, and Sheffield suffers a 20% modifier to her detection probability. The Exocet is a very-small-size target and is at very low altitude, so the detection probability is reduced by 10%. The chance of detection is now 90 − 20 − 10 = 60%.

The Type 1006 radar has a range of 6 nm against very small contacts. This is reduced by 20% (sea state 7 is now treated as 6), reducing the range to 4.8 nm. The radar horizon from a small ship to a missile at very low altitude can be as much as 22 nm, but the missile cannot be detected until it is within 4.8 nm.

4.2.5.2 Land Mass Effects. Large land masses, because of their massive radar echo, can mask smaller targets that are very close to shore. Even modern radars with highly sophisticated processors have trouble distinguishing a moving target from terrain features.

A surface radar that has land in the line of sight to a potential contact can only detect it at half its normal range. For example, if a surface-search radar has a normal detection range of 16 nm against a fast patrol boat (FPB), it will only have an 8 nm detection range if the FPB is between the radar and the coastline.

4.2.5.3 Ducting. In many parts of the world's oceans, such as the North Sea or the Persian Gulf, evaporation of seawater forms a refractive duct through which a surface-search radar's wave can travel far beyond the normal radar horizon. One might normally think that extending the radar's range would be a good thing; however, since the atmospheric conditions that produce the duct are unreliable, it is difficult to predict at what time of day and with what strength a duct will occur. Furthermore, since radar echoes travel farther than expected, they are no longer properly synchronized with the radar's electronics, and the ranges given become ambiguous and cannot be used as-is. Since ducting provides incorrect information, and the players do not know it, it is recommended that this phenomenon only be used in refereed games.

Ducting generally has a height of about 10 to 20 meters, and so only affects small ships and periscope radars. Sometimes, however, the duct can reach a height of 30 meters (the entire "very low altitude" level) and can also affect medium-size ships and helicopters flying at very low altitude. Any surface-search radar within the duct will have its radar horizon increased as shown in the table below.

For contacts within the radar's normal range, as given in Annexes J and L, they will be detected and displayed normally on the screen. If the contact is within the duct beyond normal range, it may display at any distance. Radar operators will change scale to see if the range changes, which will then tell them they are dealing with an "ambiguous" contact. In Harpoon, contacts beyond maximum range but within the duct are simply shown as being at an "ambiguous" distance. The bearing given by the radar is correct.

This phenomenon has a second effect, in that the ESM horizon is likewise increased in the same proportion. For strong and very strong ducts, the surface-search radars of large ships are detectable at greater range, although they cannot expect any benefit from the duct itself.

Example: while setting up a game, the referee rolls a die to determine the strength of a strong duct. The D6 roll is a 4, giving a multiplier of (4/2) + 1 = 2 + 1 = 3. All surface-search radars of medium or small ships and helicopters flying at very low altitude have their horizon multiplied by 3, or tripled.

Above sea state 3, or with winds above 20 knots, the wind is too strong to allow the duct to form; the air is too thoroughly mixed. Furthermore, if there is too much spray or humidity in the air (light precipitation on the Observation Conditions Table), including fairly low cloud cover (at the low altitude level), this also prevents the duct from forming.

Duct strength may be specified in the scenario's environment description, or determined randomly from Annex N.

4.2.5.4 Rain Effects. Raindrops can cause backscatter problems for radar. The heavier the rain, the greater the interference. The following table gives the degradation of radar signals based on precipitation intensity.

4.3 Electronic Support Measures (ESM)

All electronic emitters (radar, radio) emit electromagnetic energy. This emission can be detected by sensors designed for that purpose, just as passive sonars detect active sonars.

These sensors are called ESM (Electromagnetic Support Measures). Any ship or aircraft fitted with one will have it noted in its detector listing.

Some aircraft or ships have a simple form of ESM called a "radar warning receiver" (RWR), which tells them if they are being engaged by a radar-guided weapon. They will not detect search radars.

The chances of detecting a search radar's emissions with ESM are 90% during a Tactical Turn and 60% during an Engagement Turn. ESM detection is automatic during an Intermediate Turn. Weapon and fire-control radars are automatically detected at all times, due to the strength of their signal and the narrowness of their beam. A director does not radiate until it is guiding a missile or controlling a firing solution. Otherwise, it cannot be detected. Airborne interception or weapon-guidance radars are treated as weapon radars.

An ESM's maximum range depends on the type of ESM receiver and the effective radar horizon. Successive generations of ESM have made them increasingly sensitive; they can now detect emissions beyond the radar horizon by using the atmosphere's refractive properties. First-generation systems can detect up to 120% of the radar horizon. Second-generation, up to 135%, and third-generation, up to 150%. This difference in range is especially significant for airborne ESM. The latest generation of ESM lets an aircraft detect a radar emission hundreds of miles farther away than earlier generations could.

For surface-search radars, "atmospheric ducting" will also affect the range at which an ESM can detect them. See section 4.2.5.3 for details.

To save time, the 3 "ESM Line of Sight" tables give the radar line of sight modified by the percentages for each ESM generation.

Example: A Russian Tu-95RT Bear D, fitted with 1st-generation ESM, is patrolling at high altitude. It is searching for a US fleet made up of small, medium, and large ships. Using the "Line of Sight for 1st-Generation ESM" table, the Bear's player compares his altitude, high, with the various ship sizes. He can expect to detect a US radar, if it is operating, at 295, 292, and 289 nm for large, medium, and small ships respectively.

If a US P-3C, with 3rd-generation ESM, is flying at the same altitude, searching for the same type of Russian fleet, it will be able to detect them at 368, 365, and 362 nm.

A successful detection will show the type of emitting radar (for example: Top Bow, SPS-10), as well as its bearing from the detecting unit.

As with passive sonar (section 6.1.2), passive target-motion analysis can be used to obtain a firing solution. This solution is accurate enough to permit the use of terminally-guided surface-to-surface missiles (SSM) or nuclear depth charges. However, the signal's bearing cannot be determined exactly, only to within a few fractions of a degree of accuracy. For this reason, the passive firing solution will have a small area of uncertainty around it.

For an example of ESM triangulation to passively locate a unit, see the illustration on page 5-7.

4.4 Sonars

Sonars use underwater acoustic energy to detect and track targets. During World War I, available sonars were limited to very primitive passive hydrophones, active transducers not yet having been invented. These passive systems were only slightly better than a stethoscope dipped in water and could only indicate whether a submarine was somewhere in the immediate vicinity. During World War II, active sonars using quartz crystals and magnets let ASW escorts detect and localize submarines precisely enough to attack them with depth charges or anti-submarine mortars (Hedgehogs). But because these sonars operated at high frequencies, only short-range detections were possible. The postwar exploitation of captured German U-boat sonars showed that it was possible to design and build large sonar arrays allowing long-range detection, especially against noisy targets. Thus began the race for acoustic advantage. As sonar signal processing and arrays improved, submarines became quieter and quieter to escape detection.

4.4.1 Sonar Types. There are 2 sonar detection methods: active and passive. A passive sonar "listens" for sounds coming from other vessels, while an active sonar emits high-power sound pulses (commonly called "pings") into the water and listens for their returning echoes.

Some sonars are fitted only with a passive system; a few others (more rarely) are fitted only with an active system. Many have both active and passive systems, but can only carry out one type of detection at a time. A sonar's mode can be changed on every engagement turn (30 seconds).

Most passive sonars give the bearing, or direction, of the contact. However, omnidirectional passive sonars, such as LOFAR sonobuoys, will only tell you of its presence. The special use of a passive ranging array (PRA) will also provide an estimate of the target's range. Passive sonar will also let you classify, after some analysis, the type of ship detected. For their part, active sonars will give the bearing and range of the target, as a radar would (exception: CASS sonobuoys only provide range). Unfortunately, by emitting high-power sound pulses into the water, the searching ship itself becomes much easier to detect.

4.4.2 Sonar Arrays. Sonar arrays are classified by their mode of operation (active, passive, or both) and by whether they are hull-mounted or deployed from the ship.

4.4.2.1 Hull-Mounted Arrays. Hull-mounted arrays equip submarines and surface ships in 4 configurations: bow-mounted, keel-mounted, flank arrays, and deck-mounted. A bow-mounted sonar is located at the forward end of the ship. On some submarines, the array occupies the entire bow, forcing the torpedo tubes to be moved amidships. On modern surface ships, the bow sonar is often installed in a bulbous dome specifically designed to be hydrodynamic. Keel-mounted sonars are often installed on ships whose primary function is not ASW. On this type of ship, the array is located about 1/3 of the way back from the bow. Bow-mounted and keel-mounted sonars can operate in both active and passive mode.

Deck-mounted and forward-sail-mounted sonars are often passive acoustic intercept receivers (AIR) or the main active sonar on diesel submarines. Acoustic intercept receivers are similar in function to an aircraft's radar warning receiver or an ESM system. They warn the submarine when an active sonar is emitting. These systems have very broad frequency coverage, with detection ranging from low-frequency ship sonar emissions to high-frequency torpedo sonars.

Flank arrays are located along the sides of the ship or submarine and are most often passive systems. By using the length of the ship's hull, a long array can be installed, allowing detection at greater ranges than a bow-mounted array.

4.4.2.2 Baffles. Hull-mounted sonars have a blind spot, a deaf zone, caused by a plate that blocks the ship's own noise and keeps it from interfering with the sonar and blinding it. These zones, which are present even if the ship is dead in the water, are called baffles. The size and shape of these baffles vary depending on where the sonar is located on the ship's hull. A contact (ship, submarine, or torpedo) inside the baffle cannot be detected by the sonar. The baffles for each sonar type are shown in the baffle-arc table and diagram. All baffle zones are defined by bearings relative to the ship's bow (with the ship's bow at 000°).

Baffle Arcs

Hull Array	Zone Location	Baffle Size
Bow sonar	150-210°	60°
Keel sonar	135-225°	90°
Flank array (starboard)	000°-030°/150°-180°	30° each
Flank array (port)	330°-000°/180°-210°	30° each
Deck/sail (forward)	135-225°	90°
Deck/sail (aft)	315-045°	90°

4.4.2.3 Towed Sonar Array. Towed sonar arrays are deployed from the ship's stern and are literally towed through the water. There are 2 types of towed sonars: the variable depth sonar (VDS) and the passive hydrophone array. The VDS system is an active or active/passive array installed in a towed hydrodynamic body called a "fish." The VDS is similar to a hull-mounted array but is deployable, so that it can go below the thermocline where a submarine may be hiding.

A towed hydrophone array, or more simply a towed array, is a collection of passive hydrophones inside a rubber-like hose. By streaming a large number of these hydrophones together in a line, the sonar can detect targets at very long range. Unfortunately, this makes the array very long, and it simply cannot be installed on the hull of a ship or submarine, and so must be towed behind the ship. The other advantage of a towed array is that, since it is not mounted on the hull, the ship's own noise does not affect it the way it would a hull-mounted sonar.

All towed arrays are classed as "low speed" or "high speed." This is the speed at which they can be towed without reducing detection range due to flow noise.

Deploying a towed array or a VDS takes 7 tactical turns (21 minutes), and the platform must not exceed 15 knots while the array is being deployed. Once a VDS is deployed, the ship is limited to 25 knots. Because a towed array is lighter, there is less tension on the tow cable, so it can survive at higher speeds. Nevertheless, a ship or submarine is limited to 30 knots with a towed array deployed. If speed exceeds this limit, there is a 50% chance each tactical turn that the towed sonar is lost. If the ship or submarine goes astern, there is a 50% chance each tactical turn that the tow cable is severed by the propeller. There is also a 10% chance of a critical hit to the machinery, as the tow cable becomes fouled around the propeller.

A surface ship's towed sonar, when deployed, sits at intermediate depth level I, below the thermocline. This means that direct-path detection ranges will not be affected by the reductions that apply to detections across the layer, if the submarine is also below the layer. However, if the submarine is at shallow depth, with the towed sonar having crossed the layer, its detection range will be reduced. See section 4.4.4.1 for the effects of the thermal layer on detection.

A submarine's towed sonar sits one level below the submarine's own level. If the water depth is less than 100 meters, towed sonars cannot be deployed, because they would drag along the ocean floor and be destroyed.

There is a risk that a submarine may collide with a towed sonar if the conditions for a collision described in section 3.6 are met. If a collision occurs, the towed sonar is automatically destroyed, and the submarine may be affected. There is no other damage to the towing ship beyond the loss of the towed sonar. If the sonar system is a surface ship's towed VDS body, and the submarine is at the same depth level as the "fish," the submarine takes 1D6 damage points and there is a 10% chance of a critical hit to the engine room from the tow cable fouling the propeller. If the sonar system is a towed array or a VDS tow cable, and the submarine is at the same depth level as the array/cable, there is only a 10% chance of a critical hit to the engine room from the tow cable fouling the propeller.

Sonar. SONAR is an acronym for SOund Navigation And Ranging and is the general name for the family of detection systems that sense acoustic energy in the water. During World War II, active sonars were used to track submarines, because the passive sonars of the time were not sensitive enough. With the arrival of nuclear power, submarines became faster and had greater endurance, but they also became noisier and could then be detected at long range by passive systems. As technology advanced, submarines' noise levels declined and passive detection ranges shrank, to the point that active sonars once again became the dominant ASW systems.

The sonar model used in H4 uses the same figure-of-merit (FOM) values that sonar operators use to calculate a range bracket for a particular sonar against a specific target, for the part of the ocean where the ship or submarine is operating. Although it is a relatively simple equation, the variables can change an easy detection from one day to the next and from one target to another. Of course, the results of the FOM equation are almost always a bit optimistic. To correct this and put things in perspective, the passive detection range of a TB-23 towed array was 30 nm against a quiet target. In Harpoon 4, the TB-23's range has been reduced by two-thirds, to 10 nm — and remember that this number is still optimistic. Against an even harder, quieter target, such as the new Seredovinsk-class SSN, the TB-23's passive detection range drops to a small, uncomfortable 2.5 nm.

Hunting submarines has always required luck, skill, and a cool head. Unfortunately, against these modern steel sharks, a bit more luck is needed, because they are harder to find. Jules Verne proved a true prophet when he described Captain Nemo's Nautilus, in Twenty Thousand Leagues Under the Sea, as a monster of the seas. Indeed, modern submarines resemble those legendary beasts of the deep that struck at ships wherever and whenever they wished, then vanished behind a screen of invisibility. Sonar is the "eye" a submarine hunter needs to detect the submarine and attack it, hoping the submarine does not attack him first.

4.4.2.4 Towed Array Bearing Ambiguity and Stabilization (optional rule). Because of how the towed array is built, the bearings it provides (relative to the ship's heading) are ambiguous. It cannot tell whether the bearing is to the right of centerline or to the left of centerline. When a target is first detected, the sonar operator does not know which of the two directions is correct to begin tracking. This problem is known as towed-array ambiguity. Unfortunately, the only way to resolve the ambiguity is to maneuver the detecting ship enough to place the target at a radically different angle, which requires a course change of between 45° and 135° to port or starboard, to get a new angle on the target. A 180° course change will not resolve the problem, since the bearings will be exactly the same. Once the course change has been made, the correct left/right bearing can quickly be determined and tracking of the target can begin.

The problem with changing course with a towed array deployed is that once you put a bend in it (i.e., when the towed array is no longer in a straight line), its bearing information becomes worthless, and contact with the target is lost during the maneuver. After the course change has been made, it takes some time for the tow cable to straighten out again. This period is called the "array stabilization time," and it depends on the array's length and the ship's or submarine's speed. Annex M gives towed array lengths in the remarks section. The towed array stabilization table gives the time needed for the array to straighten out again, based on the ship's speed and the array's length.

Towed Array Stabilization

Time in tactical turns

Speed (knots)	5	10	15+
Short array	2	1	1
Long array	3	2	2

4.4.2.5 Dipping Sonars. Dipping sonars are winched down from hovering helicopters, from seaplanes that have landed, or from small ASW combatants sitting stationary in the water. They cannot move through the water as other sonars do, although they can easily change depth. If the platform moves anyway, the cable snaps and the dipping sonar is lost. Dipping sonars have 360° coverage and therefore have no baffle zone.

Once the platform is ready (i.e., the helicopter is hovering at very low altitude), it takes one engagement turn to lower or raise the dipping sonar to shallow depth. It takes one more engagement turn to lower it from shallow depth to intermediate depth I. It cannot be lowered deeper than intermediate depth I. As with other sonars, as long as the sonar is in the water, there is a risk of collision with submarines.

4.4.2.6 Sonobuoys. Sonobuoys are small sonars dropped by aircraft, with a radio and a float attached. A sonobuoy's hydrophone or transducer can be set to one of two depths: shallow depth or intermediate I. Once deployed, a sonobuoy's depth cannot be changed. Sonobuoys have a selectable lifespan, after which a soluble plug dissolves and the buoy sinks. On average, passive sonobuoys have a lifespan of 1 to 8 hours, while active sonobuoys have considerably shorter lifespans, on the order of 30 minutes, due to an active sonar's greater power requirements. To deploy a sonobuoy, an aircraft flies over the desired position and declares that it is dropping a buoy; buoys are assumed to land close enough to the intended position without requiring a die roll. To ensure the sonobuoy survives the water impact, the aircraft must be at medium or low altitude, with a flight speed of 325 knots or less. Any sonobuoy dropped outside these limits must be considered destroyed on impact. The sonobuoy can be used starting with the detection phase of the tactical turn following the one in which it was dropped. Sonobuoys have 360° coverage and therefore have no baffle zone. Furthermore, due to their small size, sonobuoys carry no risk of collision with a submarine.

There are various kinds of sonobuoys in service today. They range from simple threshold buoys from the World War II era to very complex vertical line arrays. The most common sonobuoy types are given below with their general description:

• Threshold: omnidirectional or directional passive search.
• LOFAR: omnidirectional passive search.
• DIFAR: passive search, gives bearing only.
• CASS: active search, gives range only.
• DICASS: active search, gives bearing and range.
• VLAD: passive search, gives bearing only.

The number and type of sonobuoys carried by a maritime patrol aircraft depends on the aircraft's size, the sonobuoys' size, and the aircraft's signal-processing capacity. For example, a US Navy P-3C Orion can carry about 87 size-A sonobuoys (36 inches long and 5 inches in diameter) and has 99 different channels for receiving acoustic data from the buoys.

4.4.3 Maintaining Contact. Sound travels farther in water than in air, but because of the changing properties of seawater, sound follows a path that is anything but a straight line. Consequently, players must check every turn whether they maintain contact with a target previously detected. Maintaining sonar contact is resolved like detecting one, except that there is a +15% modifier to the detection chance for an alerted operator. This bonus lasts up to 4 tactical turns (12 minutes) after contact has been lost.

4.4.4 Acoustic Propagation Paths. Since sound does not necessarily travel in a straight line through water, it has multiple propagation paths, which have important tactical implications. The propagation path diagram (page 4-6) illustrates the 2 most important paths.

4.4.4.1 The Direct Path and "the Layer." The thermocline (also called "the layer") is the dominant factor in acoustic detection of a target. The layer is a sudden change in water temperature, which normally decreases as depth increases. This localized boundary (by definition) between the shallow and intermediate I depth levels is an excellent sound reflector. A sonar emission that strikes the layer at too shallow an angle will bounce off and will not penetrate below the shallow-depth level. As a result, a ship on the surface will probably not be able to detect a distant submarine below the layer, because the sonar emissions will bounce before reaching the submarine's depth. However, the closer the submarine gets to the ship, the steeper the angle becomes, until the sonar emission penetrates the layer and detects it. This problem will also affect a sonar below the layer trying to detect a target above it. Consequently, if the layer is between the sonar and its potential contact, the sonar's range, whether active or passive, is halved. Since the layer only exists in calm water, a sea state of 5 or more will churn the water enough to prevent a layer from forming.

This propagation path, in which sound travels in a relatively straight line from the target to the sonar, is called the direct path.

4.4.4.2 Convergence Zones. A second, more exotic propagation path is called a convergence zone (abbreviated CZ). When a sonar emission is directed into very deep water (6,000 feet or more), the effect of increasing pressure with depth bends the emission back toward the surface. Over long distances, the sound's path takes the shape of a half-doughnut ring. In the Atlantic and Pacific Oceans, CZs tend to be concentrated about every 30 nm of distance. In the Mediterranean Sea, CZs are concentrated about every 20 nm of distance. Targets located within the CZ ring's boundaries can be detected with active or passive sonars capable of using this propagation path. A CZ ring's width is approximately 10% of its range/distance. So, for the Atlantic Ocean's CZs, the ring width would be 3 nm for the first CZ (30 nm), 6 nm for the second CZ (60 nm), and 9 nm for the third CZ (90 nm). The chance of detection within a CZ is 50%, and the only modifier applicable to a CZ contact is the +15% for an alerted operator.

The number of CZs at which a contact can be detected depends on the sonar type and the target's noise level. The convergence-zone table gives sonars' CZ value. If the target increases its speed, the number of CZs increases along with the noise it produces. For active sonars, the sonar's CZ value is the same as the passive value for a noisy target. Some active sonars have special features that increase CZ capability. This will be noted in the remarks section for the platform fitted with that sonar type.

For an active or passive sonar to use the CZ propagation path, there must be more noise produced by the target than by its own ship, and both depend on speed. Consequently, a sonar can only use the CZ propagation path if the target's noise level, multiplied by its speed modifier (from the sonar-range modifier tables), multiplied in turn by the sonar's own speed modifier, gives a final result of 2 or more. If this value is less than 2, CZ detections are not possible.

Example: a noisy contact at 10 knots has a modifier of "2" and a speed modifier of "2." A submarine with a low-speed towed array tries to detect the contact in a CZ. For speeds of 8 knots or less, the towed array's speed modifier is "1." Multiplying the 3 modifiers together gives a value of 4, which shows CZ detections are possible. If the submarine increases its speed to between 9 and 14 knots, the towed array's speed modifier is "0.5." The product of this new set of modifiers is 2 (2 x 2 x 0.5 = 2), which shows CZ detections are still possible. However, at a speed of 15 knots, the product of the range modifiers is 1 (2 x 2 x 0.25 = 1), and CZ detections are no longer possible.

There is no technique to distinguish a passive CZ contact from a direct-path passive contact, other than deduction. A strong passive contact that suddenly appears and disappears after a few minutes may be one. Sometimes deduction, or using other units, can help rule out one possibility or the other. An active CZ contact will reveal its range, thereby showing that it is a CZ detection.

4.4.5 Passive Sonar Detection. To conduct a passive sonar search, find its passive detection range in Annex M. This range corresponds to a 50% detection chance against a quiet target. This range may be modified up or down based on the target's characteristics, the detecting ship's speed, and the environment. These modifiers are listed in the sonar range modifier tables.

Once the passive sonar's detection range has been found, look up the target's noise level (given in Annex A) and the target's speed during the current tactical turn. Multiply the Annex M range by these two multipliers. Next, look up the sonar type (hull, low-speed towed array, etc.) and find the modifier corresponding to the detecting ship's speed during that tactical turn. Compare the searching sonar's range modifier to the scenario's sea-state range modifier, then multiply the passive detection range by the lower of the 2 modifiers. Finally, if any special conditions apply, multiply the passive detection range by the appropriate modifier. Passive and active sonar searches can be conducted during the engagement turn, but with a 50% range penalty for new contacts. Contacts already known to the sonar can be maintained at the sonar's normal (tactical turn) range. Exception: after 6 engagement turns, the second detection phase of the 6th engagement turn must be treated as a normal tactical turn.

Passive Sonar Modifiers

Speed Modifiers — Sonar-Carrying Ship

Ship Speed	Hull Array	Low-Speed Towed Array	High-Speed Towed Array	Range Modifier
0-8	0-8	0-14		x1
9-14	9-14	15-20		x0.5
15-20	15-20	21-25		x0.25
21-25	21-25	26-30		x0.12
26+	26+	31+		Blind

Environment and Special Modifiers

Sea State	Range Modifier	Special Conditions	Range Modifier
0-1	x2	Target cavitating	x2
2-4	x1	Launch of 1 noisy weapon	x2
5-6	x0.5	Launch of 1 quiet weapon	x1
7-8	x0.25	Target behind the layer	x0.5
9	Blind	Shallow water, VLF thru LF-MF	x0.5
		Shallow water, MF thru HF	x1
		Marginal ice zone (MIZ)	x0.5
		Pack ice	x2
		Engagement turns	x0.5
		Snorkel deployed	x2
		Submarine "ultra-quiet"	x0.5
		Submarine accelerating at 50%	x2

Active Sonar Modifiers

Speed Modifiers — Sonar-Carrying Ship: same as for passive sonar above.

Environment and Special Modifiers

Sea State	Range Modifier	Special Conditions	Range Modifier
0-1	x2	Anechoic coating	x0.5
2-4	x1	Target behind the layer	x0.5
5-6	x0.5	Shallow water, VLF thru LF-MF	x0.5
7-8	x0.25	Shallow water, MF thru HF	x1
9	Blind	Marginal ice zone (MIZ) or pack ice	x0.5
		Engagement turns	x0.5
		Submarine that has broken through pack ice	x0.5

Notes:

• Ultra-quiet noise levels can be achieved by diesel submarines if they move at 3 knots or less and shut down all non-essential equipment (no depth changes, no weapon launches, no turns greater than 10°).
• Sonobuoys do not use the passive sonar "sonar-carrying ship speed" modifier as long as they remain stationary.

Passive Sonars — Target Emission Correlation Modifiers

Target Emission	Class Modifier
Active sonar	Base + 20%
ESM detector	Base + 20%
Wire-guided/active-homing torpedo	Automatic with the acoustic intercept receiver (AIR)
Passive torpedo	Base + 20% (no speed modifier applies)

Classification Die Roll

Die Roll vs. Classification Probability (PC)	Passive Classification Data
PC	Ship/submarine class
PC + 20%	Ship or submarine, propulsion type, nationality
PC + 40%	Ship, submarine, torpedo
PC + 41%	No data
00 (natural, optional rule)	Misidentification (the referee is allowed to lie)

Example: an Akula I SSN is patrolling near its base at a slow speed of 5 knots, with a sea state of 3. An improved Los Angeles SSN, at 8 knots, tries to detect the Russian submarine with its TB-23 towed array. Both submarines are below the thermal layer.

Per Annex M1, the TB-23 towed array has a passive detection range of 10 nm. The Akula I SSN has an "ultra-quiet" noise value and is moving at 5 knots. The range modifiers corresponding to these characteristics are 0.5 and 1.0, respectively. The TB-23 is a "low-speed" towed array, and with the improved Los Angeles moving at 8 knots, its range modifier is 1. The sea state 3 range modifier is also 1. Comparing the sonar-speed modifier to the sea-state range modifier, we find they are identical. So a range modifier of 1 is used. No special condition applies here. The final 50%-chance detection range for the TB-23 will therefore be:

Very quiet target: 0.5 Target speed (5 knots): 1.0 Sonar speed (8 knots): 1.0 Sea state 3: 1.0 Passive detection range: 10.0 x 0.5 x 1.0 x 1.0 = 5.0 nm

If the improved Los Angeles were moving at 9 knots, the sonar-speed modifier would have been 0.5. Since this modifier is lower than the sea-state-3 modifier, the sonar-speed modifier would have had to be used to determine the final detection range. This would have reduced the passive detection range to 2.5 nm.

Once the final 50%-chance passive detection range has been calculated, the submarine player (or the referee) determines the 3 detection-range bands by multiplying the final range by the following boundary values:

Chance of Detection	Range Band Boundary Values
75%	0.0 to 0.4 x 50% detection range
50%	0.4 to 1.1 x 50% detection range
25%	1.1 to 1.5 x 50% detection range

To save time, Annex M3 gives precalculated boundary values for the 3 detection bands up to 60 nm. Once the boundary values are known, the submarine player (or the referee) measures the distance from the submarine to the searching platform, then finds which band the submarine occupies, if any. The searching player then rolls 1D100 to see if the submarine is detected.

Example: the improved Los Angeles SSN is 6 nm away when the American player tries to detect the Russian Akula I SSN. The final 50%-chance passive detection range, calculated above, is 5.0 nm. The detection-range band boundaries will then be:

Range	0.0-2.0 nm	2.01-5.5 nm	5.51-7.5 nm
% Detection	75%	50%	25%

If the contact's range falls exactly on a range-band boundary, it is considered to be in the shorter range band.

4.4.5.1 Noisy Evolutions. Some of the special conditions that modify passive detection range are evolutions or operating modes that generate noise. These are cavitation, weapon launches, active sonar searches, and nuclear detonations.

4.4.5.1.1 Cavitation. This occurs when a ship or submarine moves so fast that its propeller begins forming bubbles in its wake. At high speed, the propeller blades spin very fast, creating a low-pressure zone behind their leading edge. This creates water-vapor bubbles that implode once they separate from the blade. This makes noise and can sometimes erode the trailing edge of the propeller.

At great depth, the high water pressure prevents bubble formation, so submarines that want to go fast start by diving deep to avoid cavitation. Surface ships, of course, do not have this option.

If a ship or submarine cavitates, its passive detection range is doubled. To find out at what speed a ship or submarine will begin to cavitate, cross-reference the vessel's speed with its noise value on the cavitation table. If a submarine is fitted with a pumpjet propulsor, it will not cavitate. Use Shallow Depth for all surface ships.

Cavitation will not affect the use of active sonar or hull-mounted passive sonar aboard the cavitating ship itself. This is because the baffles block sound coming from that direction (this is one of the reasons baffles exist).

4.4.5.1.2 Launch Transient. When weapons are fired from a submarine, both the launch process and the weapon itself make noise. Normally, the launch process is noisy: it consists of a blast of compressed air, plus pump noise and the opening of tube doors. The presence of a quiet weapon-launch system on some submarines is noted in the remarks section or in Annex A.

4.4.5.1.3 Torpedo Noise. Once a torpedo has been fired, its own acoustic characteristics take over for detection purposes. All torpedoes in Annex F have a noisy noise value, unless it is stated in the remarks section that it is a quiet torpedo. If a torpedo has 2 or more speeds, its noisy or quiet value depends on the weapon's lowest speed. At any higher speed, the torpedo must be treated as a Noisy contact. Rocket motors and acoustic countermeasures must be treated as Very Noisy (loud) targets.

4.4.5.1.4 Sonar Emissions. Active sonar emissions are inherently very noisy. Emitting a lot of acoustic energy into the water makes you easier to detect. Active sonars are treated as Very Noisy (loud) targets and are detectable by sonars in the same low-frequency band or the adjacent band. Thus, an MF sonar can detect MF and LF-MF emissions but not HF or LF emissions. VLF-LF emissions cannot be produced by any sonar system today.

4.4.5.1.5 Explosion. Treat explosions as very noisy (loud) sound sources for passive sonar detection. Since an explosion is a very broadband sound source, all active sonar frequencies can be used to detect it (VLF, LF, LF-MF, MF, HF).

4.4.5.1.6 Nuclear Detonations. The loudest of all noises is the roar generated by a nuclear weapon. Any nuclear explosion on or below the surface within 75 nm of a sonar reduces its detection range by 75% (range modifier = 0.25) and makes CZ detections impossible. Other range modifiers continue to apply; it is simply that the background noise has become louder. This acoustic effect lasts 6+D6 hours.

4.4.5.2 Masking a Target. If there are 2 sonar contacts within ±10° of each other, the louder contact will mask the quieter one. The terms "louder" and "quieter" do not necessarily reflect the contacts' noise values, since a closer quiet contact may be louder than a more distant "very noisy" contact. To determine whether a contact is masked, find the 50% passive detection range and the sonar's range-band boundaries. The contact with the higher detection probability will mask the one with the lower probability. If the detection chances are equal, then the contact with the higher noise level will mask the one with the quieter noise level.

During target classification (see 4.4.8), when the sounds emitted by the contact are analyzed, the second contact will be discovered. This happens at whatever classification level expresses a difference between the 2 contacts.

Example: if a surface ship masks a submarine, the distinct signal will be discovered as soon as the primary contact is classified as a surface ship. If a US nuclear submarine masks the presence of another, they will need to be classified by class before their dual presence is discovered. If they belong to the same class, the distinction can only be made once their headings diverge.

4.4.5.3 Aircraft Detection with Passive Sonar. Aircraft or helicopters flying at very low or low altitude can be detected by VLF-LF and LF passive sonars. Even though an aircraft/helicopter generates a lot of noise in the air, the transfer of acoustic energy from air to water is very inefficient. Consequently, treat aircraft or helicopters flying at very low or low altitude as a very quiet target for passive detection devices.

US Electronic Nomenclature. All US electronic systems, and some Western systems, use an equipment designation system with a descriptive 3-letter code. A typical example is the surface-search radar noted in Annex J, the SPS-10.

SPS-10

The first letter indicates the platform carrying the equipment: A = manned aircraft, B = submarine, C = unmanned carrier, F = fixed ground installation, G = general ground use, K = amphibious, M = mobile ground, P = portable, S = surface ship, T = ground transportable, P = man-portable, U = multiple platforms, V = ground vehicle, W = surface ship or submarine.

The second letter is the general equipment type: A = invisible light or IR, C = carrier, D = radioactive, G = telegraph/teletype, I = intercom/public address, J = electromechanical or inertial wire coverage, K = telemetry, L = countermeasures, M = meteorological, N = sound in air, P = radar, Q = sonar, R = radio, S = special or combination, T = telephone (wire), V = visual and visible light, W = weapons control, X = facsimile or TV, Y = data processing.

The third letter designates the equipment's function: B = bombing, C = communications, D = direction-finding or surveillance, E = ejection, G = fire control, H = recording/playback, K = computing, M = maintenance & test, N = navigation, Q = multifunction or special function, R = receiver or passive detector, S = search, T = transmitter, W = automatic control or remote control, X = IFF or reconnaissance, Y = surveillance & control.

SPS therefore means a surface-ship search radar. "-10" indicates it is the 10th version of this surface-ship search radar system (and the office photocopier is an "FJH"!).

Other examples: BQQ-2 is a multi-function submarine sonar. SAR-8 is a surface ship's passive IR detector. AWG-9 is an aircraft weapon-control system. SPY-1 is a surface ship's surveillance and control radar.

Technically, all electronic designations are supposed to begin with "AN/", e.g. "AN/WLR-1." The letters stand for "Army-Navy," indicating a joint system (common to both services).

A "(V)" with a number at the end, as in "SLQ-32(V)3," indicates that it is a version of a base piece of equipment.

4.4.5.4 Acoustic Intercept Receiver (AIR). These are passive sonars designed to warn submarines and some surface ships that an active sonar is in the area. Acoustic intercept receivers can detect sonar emissions across all frequency bands, have 360° coverage (no baffle zone), and are most often automated to allow constant monitoring. Because of their specific nature, AIRs are not subject to the standard passive-detection rules described in section 4.4.5. Instead, they have a fixed detection range, and the only range modifier that applies is the thermal-layer modifier (target behind the layer), which halves the detection range. If an active sonar is within the AIR's detection range, it is automatically detected. Once the active sonar is detected, the AIR will provide the frequency band and, depending on the AIR's technology level, varying degrees of bearing information.

The oldest AIRs were derived from World War II-era systems and were barely better than button hydrophones wired to a speaker. Newer systems use larger arrays and complex processor-based signal-processing routines to improve not only detection range, but also precise bearing. They also have some range-finding capability. The acoustic intercept receiver table below gives the capabilities of the various AIR generations.

4.4.6 Active Sonar Detection. Conducting an active sonar search is very similar to the passive detection process. Find the active detection range in Annex M1 and modify it based on your own ship's speed, sea state, and any specific conditions. Once the final 50%-chance detection range is determined, calculate the range band and roll 1D100 to see if the target is detected.

Example: the improved Los Angeles with her BSY-1 sonar system has an active detection range of 6.0 nm. The submarine is moving at 8 knots with a sea state of 3; for both these conditions, the range modifier is 1. However, remember that it is the lower modifier that is used to find the active detection range. The Akula I has an anechoic coating, and both submarines are on the same side of the layer. The active detection range for the improved Los Angeles is therefore determined as follows:

Sonar speed (14 knots) = 1.0 Sea state 3 = 1.0 Anechoic-coated target = 0.5 Active detection range = 6.0 x 1.0 x 0.5 = 3.0 nm

The detection-range band boundaries are:

Range	0.0-1.2 nm	1.21-3.3 nm	3.31-4.5 nm
% Detection	75%	50%	25%

4.4.6.1 Active Towed Array. As submarines become quieter and quieter, passive detection ranges get shorter and shorter. With the advent of extremely quiet submarines, such as the US Seawolf and the Russian Severodvinsk, active sonar is making a comeback. However, these new active systems use a combination of a towed active body and a towed passive array as a receiver. Consequently, when determining the final 50%-chance passive detection range, use the low-speed towed-array section of the passive sonar modifier table for the range degradation due to ship speed.

4.4.7 Sonobuoy Detection. Maritime patrol aircraft (MPA) can only monitor as many sonobuoys as they have receiver channels. Once the channel limit is reached, no more sonobuoys can be dropped until one of the buoys in the water sinks and its channel becomes available again. See section 4.4.2.6 for sonobuoy lifespans. Furthermore, not all of an MPA's sonobuoy receiver channels are dedicated to search. Some are reserved for passive localization and for active sonobuoys used to attack a target once detected. Annex M2 lists all the MPAs in the game with their sonobuoy capacities and the number of receiver channels dedicated to search, localization, and active sonobuoys.

Sonar searches using sonobuoys are conducted the same way as with hull sonars or towed arrays, except that there is no modifier for one's own ship speed, as long as the sonobuoys remain stationary. If one of them starts moving, it has probably snagged a submarine. If an MPA flies over a sonobuoy at low or very low altitude, the aircraft's noise will saturate the sonobuoy and prevent it from detecting a target. Sonobuoys cannot survive in sea state 6 or above, as the waves will swamp them and send them to the bottom.

4.4.8 Target Classification. The sounds emitted by a ship or submarine come from the machinery inside the hull, as well as from the number and type of propellers. This set of noises is distinct for particular classes of ships, submarines, or torpedoes. By analyzing these sounds, the detecting vessel can identify or classify the contact. Before a classification attempt can be made, the detecting vessel must have passively detected the contact. Then, cross-reference the lowest frequency band with the target's noise value on the passive sonar classification table (page 4-11), which will give you the base classification probability (Pc). Modify this base Pc by the target's speed and by the number of tactical turns during which the contact has been passively detected. If the contact is correlated with an ESM detection, or if active sonar is used, a +20% modifier is applied to Pc. Then, roll 1D100 and compare the result on the classification results table. Depending on the die roll, only the contact data given on the table is provided to the detecting player.

Example: the improved Los Angeles has detected and begun tracking the Akula I SSN. After maintaining contact with the Akula I for 2 consecutive tactical turns, the improved Los Angeles attempts to classify her target. At the second tactical turn of detection, the base Pc for a VLF-LF sonar (TB-23) against a "very quiet" target is 10%. Since the Akula I is moving at 5 knots, there is no speed modifier, and there is a +5% modifier for the 2 turns of contact. Consequently, the final Pc is 15%. The die roll result will therefore give:

Pc (Die Roll)	Contact Data Obtained
15%	Akula I SSN
16 to 35%	Russian nuclear submarine
36 to 55%	Submarine
56% and up	No data

Torpedoes may also be classified before a ship or submarine maneuvers to evade them or deploys countermeasures. Since these actions are noisy, submarine commanders are reluctant to undertake them without a good reason. A torpedo is classified the same way as any other sonar contact, but there is a +20% modifier because they have very distinctive, easy-to-identify signatures. Speed modifiers do not apply when classifying a torpedo. If the torpedo is in active-search mode and the detecting unit has an acoustic intercept receiver, classification is automatic.

4.4.9 Sonar Tracks and Fire-Control Systems. The number of sonar contacts a ship or submarine can maintain is determined by the computer technology level of its sonar and fire-control system. If there are more contacts than the computer can track, the player must decide which ones to "keep" and which to drop. Furthermore, fire-control computers limit the number of wire-guided torpedoes that can be launched and controlled simultaneously. The fire-control systems table gives their capabilities based on their technology level. A submarine's fire-control system generation can be found in Annex A, in the remarks section, for each submarine.

4.4.10 Sonar Operator Professionalism (optional rule). Unlike radar systems, having a truly effective sonar operator requires a great deal of schooling, training, and practice. Remember Jonesy, the eccentric sonar technician aboard Dallas in The Hunt for Red October? While the book gives a romanticized account, it doesn't quite match reality. Good sonar operators aren't found on every street corner. It takes time and money to train good operators, which not every country can afford.

The detection range in Annex M1 assumes a competent operator is running the system, which isn't always really the case. The following table gives the capabilities of ship, submarine, or aircraft sonar systems based on their operators' level of professionalism.

The number of arrays that can be monitored at the same time depends on the operator's professionalism. The number of men working the sonar equipment matters little; what matters is the skill with which they manage to combine information from different sources. For example, if a submarine has a passive hull array, a flank array, an active ranging array, and a towed sonar (4 different systems), but its operator has a "green" professionalism level, then only 2 arrays can be used simultaneously.

The sonar operator can divert his attention once every 3-minute tactical turn, and the acoustic intercept receiver (AIR) is always monitored. The detection-range modifier is applied exactly like all other sonar range modifiers when calculating the 50%-chance detection range. Finally, the classification modifier is added to the base Pc value.

4.5 Visual Observation

The naked eye remains an important source of information. It cannot (yet) be jammed, it is passive, and it is cheap. Visual observation range depends on the observer's position and on the type of unit being searched for (ship or aircraft). This ideal range is reduced by weather and light conditions. The next 3 sections give the rules for range based on observer type, and section 4.5.5 shows the effects of weather on that same range.

Detection is checked from a group toward an enemy formation or group of units. The human eye, once fixed on an area, can easily detect nearby units, as long as conditions are the same from one unit to another.

Ranges should be tested for an air formation as a single group. Once one aircraft is detected, all the others are too. For a naval formation, test detection of the nearest unit; if it is detected, all units near it are detected within field-of-view limits. This may be the whole formation or only part of it.

4.5.1 Surface-to-Surface Observation. The visual observation line depends on the height of the 2 observers; the higher they are, the farther they will see. The "Visual Line of Sight Table" gives the longest distance (under perfect conditions) at which an observer can see another surface unit.

Visual Line of Sight

Height (m)	Height (ft)	Observing Class	Large	Medium	Small	Periscope
25	82	Large	20	17	16	2
14	46	Medium	17	15	13	2
8	26	Small	16	13	11	2
0.2	0.5	Periscope	11	8	6	1

Example: a Spruance-class destroyer, a medium-size ship, may be able to see an Osa-class missile boat, a small-size ship. Cross-referencing the medium row with the small column shows that the Spruance can see the Osa out to 13 nm, in clear daylight conditions.

4.5.2 Surface Observation from Aircraft. Air observers always see a ship's wake long before they see the ship itself. Surface unit observation ranges depend on their size. The bigger the ship, the bigger the wake.

Example: a helicopter is searching for a destroyer, a medium-size ship. Under optimal daylight conditions (no limit), the helicopter will spot the ship at 19 nm.

4.5.3 Aircraft Observation from Surface or Air. Aircraft can see other aircraft or missiles of any size at high or very high altitude at 50 nm (due to contrails). Large aircraft at medium altitude or lower are visible at 5 nm, small aircraft at 3 nm, and very small air contacts (0.1 m² size, usually missiles) are visible at 1.5 nm.

Aircraft can be detected at ranges beyond what is possible with the naked eye by using magnifying video cameras. This device is called a TCS (Television Camera Sensor) and displays a video image in the cockpit. Very small missiles can be seen at 5 nm, small aircraft can be seen at 10 nm, and large aircraft at 20 nm, when located within a 30° arc centered on the flight path.

This detection system can be used (with the radar off) to search for aircraft without emitting a radar signal. It can also be used to classify contacts detected by radar. It is affected by weather, and its range is reduced by the visibility percentage. The TCS may be noted as a detection system in Annex B (aircraft).

4.5.4 Observation and Periscopes. Surfaced submarines are treated as surface ships for visual observation. Submerged submarines can also be seen if they are at shallow depth and an aircraft passes close enough (see section 3.2.1.2), or, if the submarine is moving fast enough to produce a "Kelvin wake," at the surface.

Submerged submarines must use periscopes to gather visual information. It must be raised to be used, and as long as it is up, it is visible to others. It can be raised, used, and retracted within one engagement turn, during the detection phase. Periscopes are also fitted with a ranging system independent of radar (usually a stadimeter or a laser rangefinder). The submarine player can measure the range to a contact once per engagement turn using this device.

The chance of spotting a periscope depends on sea state and the submarine's speed. If the periscope is within visual observation range, roll 1D100 and use the probabilities given in the periscope visual detection table. This table may be used whenever the submarine raises any equipment above the water — periscope, snorkel, radar mast, radio mast — or to spot the submarine at shallow depth (see section 3.2.1.2), or to spot its Kelvin wake.

Periscope Visual Detection Table

Sea State	Detection Probability vs. Normal Periscope	Detection Probability vs. Periscope with Wake
0	0.75	0.95
1	0.50	0.65
2	0.35	0.45
3	0.25	0.30
4	0.15	0.20
5	0.10	0.15
6 and up	0.05	0.10

Periscopes cannot be seen in sea state 6 or above. A periscope produces a wake if its speed exceeds 5 knots.

In the absence of a referee, the submarine player makes the die roll himself, and his opponent is only informed if the roll succeeds.

4.5.5 Weather and Light Effects. Visual detection is greatly affected by the amount of light as well as by weather conditions. Humidity and haze in the air, not to mention rain or snow, will reduce the ideal maximum range at which something can be seen. Actual precipitation (rain, snow, fog) will drastically reduce detection ranges.

The "observation conditions table" shows how the ideal range is reduced by various weather conditions. There are 4 categories: clear day, clear night, day with precipitation, night with precipitation. Clear day and clear night are modified by weather, and clear night is modified by moon phase. Night with precipitation is not modified by the moon, since it is hidden by clouds.

Observation Conditions Table

Surface % visib.	Air % visib.	Clear Day	Clear Night (Moon)	Day w/ Precip.	Night w/ Precip.	Sigma (nm) option
-	100	Unlimited				4
-	75	Unlimited				4
100	60	V. Clear				3
75	50	V. Clear				2
50	40	Clear	Full			2
40	30	Clear	3/4			1.5
25	20	L. Haze	1/2			1.5
10	10	Haze/L. Fog	1/4	Light		1
5	5	Thin Fog	New	Moderate	Light	0.5
2	2	Dense Fog		Heavy	Moderate/Heavy	0.5

Note: a cloudy night with no precipitation, but with moonlight blocked by clouds, is treated as a new moon.

Visibility will be given in the scenario statement, or may be deduced from the time and date. For example, on a clear night with a half moon, the average visibility distance is 25% of the normal (clear-day) distance.

Example: a Spruance-class destroyer tries to see a small surface contact. The maximum viewing distance between the 2 units is 13 nm. But it is night, and light rain is falling. The distance is then reduced to 5%, or 0.65 nm.

Viewing distance may also be modified by ship actions or special conditions. For example, a ship that is conspicuously lit up will be visible from farther away at night. These modifiers are:

Observation Modifiers:

• A ship on fire triples its detection distance, without exceeding the horizon distance.
• A ship with its lights on can be seen at double the night range, without exceeding the horizon distance.
• Ships moving faster than 20 knots leave large wakes and can be seen at double the range for air detection.
• Ships moving slower than 5 knots leave small wakes and can be seen at half the range for air detection.
• Gunfire triples the surface and air detection distance at night, without exceeding the horizon distance for surface detection.
• Missile launches quadruple surface and air detection distance at night and double it by day, without exceeding the horizon distance for surface detection.
• A group of 3 or more aircraft is detected at double the normal distance.
• Ships near land, stationary, and camouflaged are detectable at a quarter of the normal distance.

4.5.6 Visibility Variation (optional rule). If all players agree, it is possible to vary the exact visibility range from turn to turn. This represents not only local variations in visibility but differences in the lookouts' own performance. The amount of variation (called "a Sigma") changes with visibility conditions. For example, with 50% surface visibility, the variation is 2 nm, meaning an ideal observation range of 13 nm, modified by 50% to give 6.5 nm, can vary between 4.5 and 8.5 nm.

After calculating the observation range based on current weather conditions, note the Sigma from the right-hand column of the observation conditions table. Roll 1D10 on the visibility variation table and cross-reference the result with the Sigma. The result is the amount subtracted from or added to that turn's observation range. The Sigma will change from turn to turn, and must be rolled for each unit, on each turn it attempts a detection.

If a player tries to detect more than one type of unit, for example both aircraft and ships, he may apply the same D10 roll to both detections.

Using this rule reintroduces uncertainty about the current visual detection range, but will also slow the game down a bit. It should not be used during intermediate-turn movement.

4.5.7 Clouds. Clouds do not reduce observation range, except for nighttime surface ranges, but they can block the line of sight between ships and aircraft, or between 2 aircraft at different altitudes.

Clouds form layers 1,000 to 6,000 meters thick, from low to very high altitude. Although sky coverage is sometimes total (100% cover), it can also be broken (75%), scattered (50%), or few (25%).

An aircraft in clouds can neither see nor be seen. Cloud cover blocks the line of sight between aircraft on either side of it, or between an aircraft above it and the sea surface. Establishing visual contact is still possible, however, as long as cloud cover is not total.

The chance of spotting an aircraft through cloud cover depends on the cloud coverage. Aircraft size and number do not matter. A group of aircraft flying together is treated as a single object for spotting purposes.

A unit visually searching for an aircraft must roll 1D100 during the detection phase. If the result is greater than the cloud coverage, it sees the aircraft. If the result is less than or equal to the cloud coverage, the aircraft is not visually spotted. Players may attempt to spot their targets through cloud cover on every tactical turn, and the detection only lasts for that one turn (the turn of detection).

Sighting is mutual. A gap in the cloud cover allows for reciprocal observation.

Aircraft cannot engage in a dogfight within clouds. They can try to evade attacks or visual detection by hiding in clouds. If an aircraft wants to hide in the clouds, it can add 25% to the cloud coverage (since the pilot is flying his aircraft within the clouds and doing his best to avoid gaps that would let him be spotted). The aircraft must also be at the same altitude as the clouds. Likewise, since the pilot is focused on staying within the clouds, his aircraft will only cover half its normal range at that throttle setting and altitude.

Example: a group of 2 aircraft is flying at medium altitude. There is a scattered cloud layer (25% coverage) at low altitude. A surface observer must roll 1D100 to see if he spots the aircraft. He rolls a 15, which is less than the cloud value; the aircraft is therefore hidden by the clouds.

The next turn, the aircraft realize an observer is trying to spot them. They then descend to low altitude, but their chances of staying hidden increase by 25%. The ground observer must now roll 51 or higher to spot them.

4.5.8 Identifying Visual Contacts. When a unit is first sighted, it is barely more than a dot contrasting against its visual background. Although its position may immediately give some clues to its nature, exact identification usually takes a bit more time.

By day, the basic ship type (warship or merchant) can be distinguished at 75% of observation range. The exact type (the ship's class) is known at 50% of observation range. Aircraft must be at low altitude. By night, the basic type is known at 50% and the exact class at 25% of observation range.

Example: a lookout on a Spruance-class destroyer (medium-size ship) spots another medium-size ship on a clear night with a 3/4 moon. The maximum surface-to-surface observation range between 2 medium-size ships is 15 nm, modified by the 3/4-moon's 40%, giving 6 nm. Initial detection occurs at 6 nm. The visual contact can be identified as a warship at 3 nm (half of 6 nm), and classified as an Udaloy-class destroyer at 1.5 nm.

4.5.9 Ship Sighting and Miniatures Play. Until a ship is seen by the enemy, use a counter to mark its position. Dummy counters may be used to confuse the enemy about the number of units on the playing surface. Once the ship is sighted, replace it with a counter showing the general ship type, e.g. a large warship, a small warship, a merchant ship, etc. When a ship is correctly identified by class, replace the counter with a miniature or counter showing the specific ship type.

4.6 Infrared Detection Systems (Thermal Imagers)

Modern IR systems are installed not only on naval aircraft but also on surface ships. Their most important characteristic is that they are passive, letting ships shut down their search radars while still keeping a warning system against missile attacks.

A ship's passive IR scanners work like FLIRs. They can display contacts on a computer or video screen if the operator wants to examine a particular contact in detail. Like other passive detection systems, they cannot provide range information. With earlier generations this was not a problem, due to their relatively short range. More recent systems are most often fitted with a laser rangefinder.

All IR detection systems have an 80% chance of detecting a unit on each tactical turn, and a 50% chance on each engagement turn. As with radar, once a contact is detected, it remains detected as long as it stays within the detection system's range and the system is operating. Detection range depends on the IR detection system's generation and on the type of contact being sought. The IR detection system range table gives the range for each generation.

Infrared Detection System Range

IR Generation	Small/Medium Ships or Stealth Aircraft/Missile	Small Ships or Subsonic Aircraft/Missile	Large Ship or Supersonic Aircraft/Missile
1	1 nm	2 nm	4 nm
2	2 nm	5 nm	7 nm
3	3 nm	8 nm	10 nm
4	4 nm	10 nm	12 nm

IR ranges are reduced by water and air. The more humidity, the greater the reduction.

Precipitation	% Degradation
Drizzle – light rain or fog	50%
Moderate rain or fog	75%
Heavy rain or fog	100%

Example: the French DIBV 10 Vampir is a 2nd-generation IR system. It may have a detection range of 2 nm against a stealth ship, aircraft, or missile, 5 nm against small or medium ships, small aircraft, or subsonic missiles, and 7 nm against large ships or aircraft, or against any supersonic aircraft or missile. In light rain, these ranges must be reduced to 1 nm, 2.5 nm, and 3.5 nm.

At first, an infrared detection system usually only detects a shapeless mass of IR radiation. However, as the target gets closer, enough IR energy is received by the detection system for it to produce a recognizable image. Consequently, a target can be visually classified (ship class or aircraft type) at half (1/2) the detection range.

4.6.1 Shipboard Passive IR Scanners. Shipboard passive IR scanners will be listed as one of a ship's detection systems in Annex A. These entries will also show which generation the detection system belongs to. For example, the French La Fayette class's detection systems entry reads "DIBV 10 Vampir (2nd gen)," meaning it is a 2nd-generation detection system.

Passive IR scanners are usually used more for missile warning than for general search or as a fire-control system. As a passive system, the scanner cannot provide any range, only a bearing and an altitude. This is enough to cue another detection system or a weapon, or to trigger countermeasures.

Scanners can be electronically linked to direct the ship's defense systems. So, if the scanner detects something during the detection phase, the ship can open fire during the following reaction fire phase.

4.6.2 Forward-Looking Infrared (FLIR). This optronic system is used as a search and air-classification detection system. Video images allow classification by type/class. It has a field of view limited to 12° for search and 3° for determining course and for classification.

4.6.3 Infrared Search and Track (IRST). These systems are used as passive tactical optronic search systems. They cannot provide range, but this is not necessary since their range is very short. 1st-generation systems (US F-106 and F-4) only worked against a target's rear aspect (±60° arc behind the target).

2nd-generation systems were fitted to the F-14A, MiG-29, Su-27, and Rafale. Cryogenically cooled, they can pick up a contact from any angle.

3rd-generation systems provide very good imaging capability and detection from any angle.

The operating arc is ±60° from the heading for all systems.

4.7 Magnetic Anomaly Detector (MAD)

MAD is used by ASW aircraft to detect submerged submarines at periscope, shallow, and intermediate depths. MAD detects the distortion of the Earth's magnetic field caused by the submarine's metal hull. The searching aircraft must be at low or very low altitude, and will detect a submarine within 0.5 nm at periscope or shallow depth, and within 0.25 nm at intermediate depth. It will not detect a submarine at deep or very deep levels. MAD range against a titanium-hulled submarine is halved.

MAD detection chances are 80% per tactical turn. MAD detection systems cannot be used during engagement turns, nor during intermediate turns.

4.8 Laser Detection Systems

Not all of these devices are detection systems in the strict sense, but they are listed under the detection systems heading for aircraft in Annex B, and so are included here. They are all optically directed, and many are accompanied by light-amplifying video systems or IR imaging and display systems, and so are not affected by darkness.

4.8.1 Laser Rangefinders. These are often listed as part of an aircraft's or ship's detection systems, particularly for attack aircraft. They feed range information directly to a weapon's fire-control computer. They have no effect in game terms.

4.8.2 Laser Designators. These may be carried in a removable pod or built into the fuselage. They are used to designate targets for laser-guided weapons. These may be dropped by the same aircraft carrying the designator or by another.

A designator can illuminate a target on each 30-second engagement turn, and must have a clear line of sight to the target.

4.8.3 Laser Rangefinder and Marked Target Seeker (LRMTS). This system not only finds a target's range, but can also find a target illuminated by another designator. This system is handy for ground troops wanting to show an aircraft which target to strike.

4.8.4 Amethyst ASW Detection System. Carried aboard Russian Tu-142 Bear F Mod 4 aircraft, the Amethyst system lets the aircraft locate a submarine using a blue-green laser scan. The aircraft must fly at 100m altitude at exactly 200 knots in a straight line. The short-range (100 yards) laser scan on both sides of the aircraft has a 90% chance of detecting a submarine at shallow depth. If the submarine is detected, the ASW aircraft will know its exact position and depth. It cannot, however, detect a submarine at intermediate depth or deeper.

Chapter Five – Weapon Characteristics

There are many ways to direct a weapon toward its assigned target. If a weapon is guided, its actions after launch will depend on the type of seeker and guidance system it uses. Shells, though generally lacking a guidance system, are also controlled by a director.

5.1 Weapon Directors

"Director" is a generic term for the fire-control equipment that aims a ship's guns and missiles. It is required for the operation of many weapons. Directors are generally radars (combined with visual, infrared, or laser backup systems), which measure the bearing and range to the target and calculate the firing solution for the weapon type associated with them. For certain guided missiles, they track the target and send course corrections after launch.

Weapon directors are noted on the weapon lines in the ship listings in Annex A. If a director is noted for a weapon, that weapon needs it to function properly; if none is noted, the weapon can fire without a director. Weapon directors are listed in Annex K.

A ship can normally engage as many targets as it has directors. A ship fitted with 1 gun director and two guns can only open fire on a single target, as long as the director controls both guns. However, if the gun system has a local-control mode, each gun can engage a different target, but only one can use the director. The other will have its chances of hitting its target significantly reduced. Weapons without directors, such as torpedo tubes and some missile launchers, can only engage one target per Engagement Turn, but they can fire several times per Engagement Turn if the weapon's rate of fire allows.

The only exceptions to this rule are inertially-guided weapons, which include the US Navy's Aegis air-defense system. Aegis uses inertially-guided surface-to-air missiles with semi-active radar terminal guidance, plus a powerful integrated radar/fire-control system that lets it engage multiple targets (see the Aegis sidebar, page 5-3).

Directors that control weapons only capable of engaging surface or air targets are always ready to engage that type of target. Directors that control more than one weapon, or mixed weapons (capable of engaging both surface and air targets), must be set to the correct mode. Director modes are described in Annex K as: A for air targets only, S for surface targets only, or A/S for air or surface targets.

Mixed directors must be set to one of 3 modes: /A (Air), /T (Transition), or /S (Surface). Their mode is selected during the order-writing phase. A director can change mode, but this takes it a full Engagement Turn.

Weapons controlled by a director in Transition mode cannot fire, unless they have a local-control mode. Weapons controlled by a director in air mode can only engage air targets. Weapons controlled by a director in surface mode can only engage surface targets. Hovering helicopters may be engaged as either air or surface targets. A missile director cannot change target, mode, or direct another missile at the same target until the first has hit or missed its target, been cancelled, or been shot down.

A missile director that is busy at the start of an Engagement Turn is considered busy for the entire turn (unless the system is autonomous, see 5.1.2).

Naval gun systems are aimed and controlled by directors, which measure the range to the target and calculate the corresponding elevation and bearing angles. A director will often control several identical guns mounted together, and is generally physically separate from them. If a gun mount is hit, and the critical-hit roll indicates the fire-control director, then all guns guided by it must switch to local-control mode (if possible), since there will then no longer be a director to control them.

5.1.1 Guns in Local-Control Mode. Some guns can fire without a director, in a mode called "local control." Guns that can fire in local mode are marked "Optical (OP)" among their possible control modes in Annexes C1, C2, and C3.

In local control, a crew aims and fires the gun manually. When this mode is used, the base to-hit chance (Ph) given in the Annex is halved, for both surface and air targets. Modifiers are then applied. One beneficial effect: there is no penalty for sea-skimming (Very Low Altitude) targets. Guns that are not meant to have directors, for example those with only a local-control mode, do not suffer this penalty.

5.1.2 Autonomous Weapon Systems. Most weapon systems have a human "in the loop" somewhere, if only to decide which target to engage. Some of the newer control systems, however, are fully automated, and can select the most threatening target, fire on it, confirm whether it was destroyed, then fire again or select another, all without human intervention.

Autonomous systems can open fire on a target during the second fire phase of an engagement turn even if they already opened fire or engaged a target during the first fire phase.

Example: after the first movement phase of an engagement turn, a Phalanx defensive gun attacks a group of 2 missiles that will reach its ship in two movement phases. It opens fire during the first fire phase and hits one of the 2 incoming missiles. Because it is autonomous, it knows it destroyed the target and can instantly open fire again. It opens fire again during the second fire phase and hits the second missile. Not all defensive guns have this capability. The Russian AK-630 rotary 30mm gun uses a conventional radar director and will only be able to fire once. However, when linked to the Kashtan [SA-N-9 Kinzhal] missile system, the AK-630 becomes autonomous.

Since they can open fire in both the second and the first fire phase, autonomous missile systems have their rate of fire halved (see 5.2) and are assumed to fire at only half their rate during each fire phase of an engagement turn. Autonomous gun systems have a normal chance to hit their target on each fire phase.

Autonomous weapons can switch between air and surface modes within the same engagement turn. They do not need a full turn to change mode.

The US Ticonderoga, the US Arleigh Burke, and the Japanese Kongo class are fitted with the Aegis system, which is considered autonomous. The British Seawolf and the Russian Kinzhal SAM defense system are also autonomous. Most Western close-in weapon systems (CIWS), such as Phalanx, Goalkeeper, Sea-Zenith, and Meroka, are autonomous systems, as is the Russian Kashtan [CADS-N-1] and the AK-630 gun system (when paired with the Kinzhal SAM system).

5.2 Rate of Fire

If a weapon has no rate of fire noted in the ships' Annex A, it can only fire once per tube or rail per Engagement Turn. Guns may fire several times, depending on their caliber. Multi-barrel weapons, such as the Russian BRU series, will fire all their tubes simultaneously in one "salvo." Rotary guns, such as the American Phalanx, will fire a "burst" of several hundred rounds. Multi-cell missile launchers can fire 4 rounds per Engagement Turn, if no rate is specified in the "Remarks" section. Firing missile(s) during the second fire phase of an Engagement Turn halves the number of missiles that can be fired during the first phase. Either everything is fired in the first phase, or half in the first and the rest in the second.

Some weapons have a rate of fire higher than the number of shots the launcher carries. For example, a Mk29 NATO Sea Sparrow launcher has a rate of fire (ROF) of 15 but only carries 8 missiles. The high rate of fire reflects the launcher's physical capability, and means that even during Reaction Fire, the launcher can fire.

Absent other guidance in the rules, assume all weapons are automatically reloaded from below-deck magazines and will be ready to fire the next Engagement Turn. If a weapon is noted as manually loaded in the Annexes, assume it takes 2 Tactical Turns to reload a gun mount, missile rail, or torpedo tube.

Although additional reloads are noted in the "Remarks" section for a particular ship, only the ammunition given on each gun mount's weapon line is available.

Air-launched guided weapons fired against surface targets can be fired at a rate of 2 per fire phase of an engagement turn, against the same target or against two different targets. Any unguided weapon may be dropped or fired during the same fire phase. 4 air-to-air missiles may be launched per engagement turn provided they share the same target. Aircraft with multiple-launch capability (noted in the remarks) can launch missiles at different targets.

Submarines can launch up to 4 torpedoes per engagement turn, but the number of wire-guided weapons that can be controlled depends on their fire-control system. This is described in section 4.4.9.

5.3 SSM, SAM, and ASM Missile Guidance Systems

These systems are used to guide missiles against naval, air, or land targets. The missile guidance system type is given in Annex D for a naval SSM or SAM, and in Annex G for an ASM. Annex S gives the guidance system type for land-based SAMs.

5.3.1 Manual Command Guidance (Cmd). The launch platform controls the missile's course by tracking both the target and the missile, sending the missile steering commands. The missile moves at maximum speed along a course that leads it directly to its target, changing direction each phase to correct its course based on the target's movement. The firing platform must be within radar line of sight of the target at launch and at all times until the missile impacts. If radar line of sight is lost/broken (or if the missile's weapon director is destroyed), the missile misses its target. The weapon director usually controls one missile at a time. Another missile cannot be launched and controlled until the first has aborted, been destroyed, or completed its attack on its target. Some systems can control more than one missile per weapon director. This information is given in the missile remarks noted in the annexes.

5.3.2 Beam Rider (BR). The launcher controls the missile's course by aiming a radar at the target. The missile then follows (or "rides") the beam to the target. The missile moves at maximum speed on a course that leads it directly to the target, changing course each phase to compensate for the target's movement. The firing platform must be within radar line of sight of the target at launch and at all times until the missile impacts. If radar line of sight is lost/broken (or if the missile's weapon director is destroyed), the missile will miss its target.

Aegis and Cooperative Engagement Capability. The main components of the Aegis system are the SM-2 missile, the SPY-1 radar, and the combat system that links the two. The combat system is an electronic and computer suite that processes and distributes contacts detected by the radar and, under human control, engages hostile targets. Each element of the system is a major improvement over earlier components, and Aegis is the first system designed as a fully integrated system.

In a typical 1960s-era destroyer engagement, an aircraft had to be detected by an air-search radar. The blip appeared on the radar display in the CIC, and the air-search radar operator reported it by intercom to the Tactical Action Officer (TAO). The contact's position was manually plotted onto a vertical plexiglass display so the TAO could assess the threat it posed.

If the TAO decided to engage the target, he informed the weapons officer, who ordered the weapon-direction system operators to "lock" onto the target on their dual air-search radar display. The operator, using a joystick, would place a circular cursor over the blip. This signaled to the operator seated in the gun director, one deck above, where to look. The operator (usually the gunnery officer) manually trained the director to the indicated bearing and began searching for the target. Once located, he locked the Mk25 fire-control radar onto the target and ordered the mounted gun to open fire. The entire process could take 1 or 2 minutes.

In every case, a person carried out a task that required no decision-making, just manual skill and knowledge of the equipment. The TAO was the only human indispensable to the decision loop.

The Aegis combat system automatically detects and tracks all contacts, using the data supplied by the SPY-1 radar. This requires great computing power, not only to pick out the real contact from other symbols displayed on the radar screen (a task normally done by a human eye), but also to counter jamming or radar countermeasures and to track existing contacts.

The second major component of Aegis is the SPY-1 radar itself. Most radars use a mechanically rotating search antenna, spinning the parabolic dish almost everyone remembers. The SPY-1 uses an electronically-scanned radar, which, instead of an antenna, has 4 faces, each made up of 4,000 elements pointed in 4 directions. These elements let the beam be steered electronically and scan an area much more frequently than a rotating antenna, allowing newly appearing contacts to be quickly detected.

Once detected, the computer can change the shape of the radar beam, switching from a vertical fan (effective for sweeping a large volume) to a narrow pencil beam thin enough to track a known target. Indeed, once the radar knows a target is present, it can "look" at it more often than a search radar's normal rate, to provide precise position data. It can also search for new targets, while tracking existing ones and feeding fire-control data at the same time.

The weapon director generally controls one missile at a time; another missile cannot be launched and controlled until the first has aborted, been destroyed, or completed its attack on its target. A minority of systems can control more than one missile per director. This information is given in the missile remarks in the annexes.

5.3.3 Track Via Missile (TVM). The ship controls the missile by tracking both the target and the missile, sending its guidance commands over a radio control channel. The missile moves at maximum speed on a course that leads it directly to the target, changing course each phase to compensate for the target's movement. The firing platform must be within radar line of sight of the target at launch and at all times until the missile impacts. If radar line of sight is lost/broken (or if the missile's weapon director is destroyed), the missile will miss its target. Since there are multiple radio control channels, the weapon director can control several missiles at once. The number of targets that can be engaged is given in the weapons annex, in the remarks column.

5.3.4 Active Radar Homing (ARH). The missile has its own radar. Once activated, the missile does not need to be guided by another unit. The missile moves at maximum speed on a course that leads it directly to the target, changing course each phase to compensate for the target's movement. The firing platform must be within radar line of sight of the target at activation. If radar line of sight is lost/broken, the missile will miss its target. ARH systems cannot distinguish a ship less than 5 nm from shore from the coastline itself. They cannot attack land targets.

5.3.5 Semi-Active Radar Homing (SARH). The radar guidance system, called an "illuminator," is pointed at the target, and the missile homes in on the reflected radar signal. The designator may be mounted on the launch platform or on another unit. The missile moves at maximum speed on a course that leads it directly to the target, changing course each phase to compensate for the target's movement. The target must be within radar line of sight of both the missile and the designator at launch and throughout the flight, until impact. If radar line of sight is lost or the designator is destroyed, the missile misses its target. Any number of missiles may be launched at a target.

Range against a non-maneuvering air target is increased by 50% for SARH-guided missiles. This applies to short-range weapons, like the RIM-7M, as well as to long-range weapons. The reason for this bonus is that a warned aircraft will maneuver and dodge, particularly violently. The missile will then expend most of its energy reaching its target. This is a function of the SARH guidance method, which tends to be poorly suited to pursuing turning targets. Command-guided systems do not have this problem. SARH terminally-guided missiles, like the SM-2, also do not have this problem, since the mid-course trajectory update gives a particularly efficient intercept course. This range increase is not affected by the final evasive maneuvers of the most advanced anti-ship cruise missiles, such as the French Exocet MM40 Block 2 or the Russian P-270 Moskit [SS-N-22], since these maneuvers are only carried out in the very last part of the flight.

For surface-to-air missiles with I/M/TSARH guidance, each director can designate 2 targets in a fire phase. Thus, an Aegis cruiser with 4 directors can engage 8 targets on each fire phase of an Engagement Turn, for a total of 16 targets per Engagement Turn.

5.3.6 Home on Jam. This kind of specialized passive guidance is not a new guidance system, but rather a mode that most radar-homing systems can use against jamming. Early jammers emitted a "barrage" of white noise, designed to blind the missile's radar guidance system. More recent passive radar guidance systems (2nd generation and later) counter this jamming by homing on the jammer's powerful signal. This feature, sometimes noted separately for certain missiles, has been factored into the anti-ship missile attack tables, and requires no player action to trigger.

5.3.7 Semi-Active Laser Homing (SALH). A laser, called a designator, is aimed at a target and illuminates it. After launch, an SALH missile's seeker follows the laser beam reflected off the target. The unit that launched the missile, or another unit, may carry the designator. The missile moves at maximum speed on a course that leads it directly to the target, changing course each phase to compensate for the target's movement. The target must be within line of sight of the weapon and the designator at launch and throughout the flight, until impact. If line of sight is lost/broken (or the weapon's designator is destroyed), the missile's chances to hit are reduced to 1/4 of their value. Clouds, dust, smoke, haze, and fog can obstruct the laser's line of sight. See section 6.3.4.2.2 for details.

Any number of missiles may be fired at the same target. All the seekers then aim for the same point marked by the laser beam, but only the first 2, assuming they reach the target during the same movement phase of the turn, will have a normal chance to hit. Smoke and explosion debris will quarter the hit chances of any weapon with a similar guidance system arriving on target during later movement phases. If several different weapon types arrive on target during the same movement phase of an engagement turn, and at least one is SALH, the fastest weapon hits first.

5.3.8 Infrared Homing (IRH). The missile is fitted with a guidance system that homes on heat sources. The missile moves at maximum speed on a course that leads it directly to the target. The target must be within line of sight of the firing unit at launch. IRH missiles do not need a director, and the only limit on the number of missiles fired at a target is the launcher's rate of fire.

5.3.9 Electro-Optical (EO) Homing. The missile's guidance system is fitted with a TV camera, with which the operator locks onto the target. The operator must then keep the weapon's camera centered on the target until impact. Some guidance systems only work in daylight. These are noted as EO (D). Others are sensitive to low light levels and can operate by day or night. These are noted as EO (D/N). The target must be within line of sight of the unit guiding the weapon, which is not necessarily the unit that launched it, in order to maintain the digital link between the weapon and the guiding unit. If line of sight is lost/broken (or the weapon's designator is destroyed), the missile's hit chances are reduced to 1/4 of their value. Dust, smoke, haze, and fog can obstruct line of sight.

Second-generation EO guidance systems do not need a clear line of sight to the target at launch. The operator must have line of sight to the target once the missile has covered half the distance to the target, since he must maintain the link with it for the remainder of its flight time.

EO missiles do not need a director, but they require an operator to manually guide the weapon to its target. An aircraft or ship may launch as many EO-guided weapons as its rate of fire allows, provided there is a separate guiding unit for each — one operator can only guide one weapon at a time.

5.3.10 Imaging Infrared (IIR). This guidance system is very similar to the EO system, except that it uses a heat-sensitive TV camera that the operator locks onto the target. The operator then keeps the target centered in the weapon's camera until impact. Imaging infrared weapons can operate by day or night. The target must be within line of sight of the unit guiding the weapon, which is not necessarily the unit that launched it. If line of sight is lost/broken (or the weapon's designator is destroyed), the missile's hit chances are reduced to 1/4 of their value. Dust, smoke, haze, and fog can obstruct line of sight.

Second-generation IIR guidance systems do not need a clear line of sight to the target at launch. The operator must have line of sight to the target once the missile has covered half the distance to the target, since he must maintain the link with it for the remainder of its flight time.

IIR missiles do not need a director, but they require an operator to manually guide the weapon to its target. An aircraft or ship may launch as many IIR-guided weapons as its rate of fire allows, provided there is a separate guiding unit for each.

5.3.11 Passive Radar Homing (PRH or ARM). Passive radar homing (PRH) missiles and anti-radiation missiles (ARM) do not need a director; they home on the electromagnetic emissions given off by the target's radar. The term ARM (Anti-Radiation Missile) is used to describe ASMs and SSMs fitted with specific types of guidance systems; the term PRH (Passive Radiation Homing) is applied to SAMs and AAMs, but the guidance principle is the same.

First-generation weapons had a radar type preset before the aircraft left the ground, which could not be changed during flight. As a result, the attacking player must identify a specific radar: for example the SPS-48, or Bass Tilt, or DA.08. If that radar type is not present, the missile cannot be used. Many first-generation ARMs could be fitted with different seekers depending on the target's radar type.

The unit launching the missile must be within ESM range of the emitting radar, and within missile range. Some aircraft are not fitted with ESM and must therefore carry a detection pod in order to detect target radars. If an aircraft requires a pod, this must be noted as part of the aircraft's payload as well as in the remarks column of the weapons annex. The radar must be emitting at the moment of launch (except for loitering ARMs) for the missile to be fired.

As long as the radar keeps emitting, the missile will home on it at maximum speed. If the radar stops emitting, first-generation missiles will "go ballistic" and miss their target. If the radar resumes emitting while the missile is still in the air, the guidance system will reacquire the target and home on it as before.

Second-generation ARMs are fitted with a memory system. They can store the location of a stationary target emitter once the guidance system has locked onto it. Their chance of hitting the radar is halved if it is switched off at the moment of impact. This rule only applies to stationary targets. If a moving ship shuts down its radars, the missile will miss its target. If the radar resumes emitting while the missile is still in the air, the guidance system will reacquire the target and home on it as before. Missiles fitted with a memory system are noted as such in the remarks column of the annex.

Third-generation ARMs additionally have the ability to redirect their guidance system while in flight. In other words, after the aircraft has launched its missile, the missile can react to radars it detects. The radar signal may be detected by the aircraft's own ESM system, by a dedicated external pod, or by other units, and then relayed to the missile-launching aircraft.

HARM: a special capability of the US AGM-88 HARM is the ability for certain aircraft to conduct launches without line of sight to the target. The F-4G and EA-6B, both fitted with their own ESM, and F-16s fitted with a HARM targeting pod, can launch a HARM in a direction, then steer it onto the target during flight. Each turn, the change in heading cannot exceed 60°, and the missile's total distance traveled cannot exceed its stated range. Furthermore, only these platforms can fire the HARM at its maximum range of 70 nm. Other aircraft carrying the HARM can only launch it at half its maximum range, i.e. 35 nm.

If the missile does not detect a radar emission before being launched, nor at any point during its flight time, it cannot use its memory system. The missile's guidance system has a 60° field of view.

ALARM: the British ALARM (an air-to-surface ARM) has a special feature. It can loiter: in other words, descend braked by a parachute while waiting for an emitter to reveal itself, then home on it.

When launched, ALARM can attack a target directly, or be programmed to climb to high altitude and deploy a parachute. It will then wait at high altitude for up to 5 engagement turns immediately after launch. It will then descend to medium altitude over 5 turns, then to low altitude over 2 turns, and finally hit the surface and self-destruct.

The guidance system's detection field extends 5.4 nm to each side and 16.2 nm forward. If an emitter it is configured for switches on within detection range, it will jettison its parachute and dive (unpowered, but guided) onto its target. This lets the attacking aircraft fire an ARM as it approaches a well-defended target, then begin an attack run while the missile covers him.

The missile can be programmed for three priority emitters and cannot be reconfigured in flight.

5.3.12 Inertial (I/-). This guidance type is nothing more than a form of advanced dead reckoning, measuring the forces acting on the missile during its flight to its target. After launch, the missile flies to a point specified by the player that can no longer be changed. This must be a geographic point that cannot move. Once launched, the missile flies straight to the designated point at maximum speed until it reaches its target, where its warhead detonates.

All inertial systems generate a small drift, on the order of 0.5 to 1 nm per hour of flight. This is fine for strategic nuclear missiles, but even with pinpoint accuracy, these are completely useless against moving targets.

Inertial missiles do not need a director or any control system from the launching unit. They do not need line of sight, but they require a fixed target point.

Some inertially-guided missiles can use waypoints. Preset before launch, the missile will fly from one to the next until reaching its final destination. The total distance covered cannot exceed the missile's range, and the maximum course change at each waypoint cannot exceed 90°.

5.3.13 Global Positioning System (GPS). The global positioning system is a constellation of navigation satellites that lets anyone with a receiver determine their exact position to within a few meters. The Russian GLONASS version gives identical results. The only requirement is that several satellites must be above the horizon, but the constellation is designed so that this is always the case.

Unlike inertial guidance, there is no drift over time. A GPS-guided weapon is just as accurate six hours after launch as it is one minute after. As with inertial guidance, a GPS-guided weapon will fly to a position, or to a series of waypoints, given by the launching player. Upon reaching its final destination, the missile will attack or activate a terminal guidance system.

5.3.14 Terminal Guidance (-/T--). This combination of guidance systems uses inertial or GPS guidance to move the weapon near the target, where the second guidance system has a good chance of locking onto it and directing it onto the target (the "terminal phase"). This lets the launcher leave the area, since it does not need to guide the weapon. It also lets the launching unit, if it has information from another source, launch its weapons even if it cannot see the target, or find the target even if it is beyond the horizon, and so launch the weapon from a relatively protected location. This class of guided weapon is often called "standoff" or "launch & leave."

Terminally-guided missiles can have several forms of terminal guidance. The most common include active radar homing (-/TARH), infrared homing (-/TIRH), passive radar homing (-/TPRH), semi-active radar homing (-/TSARH), and many others.

Many weapons with this type of guidance, particularly anti-ship missiles, also have 2 different launch modes. Specifically, a weapon can be launched in Range and Bearing Launch mode (RBL) or in Bearing Only Launch mode (BOL). In RBL mode, the launcher gives the missile a bearing and a distance relative to its own ship, from which the terminal guidance system will activate and begin searching for its target. Bearing-only launches are covered in section 5.3.14.1.

Once the missile has reached its activation point, the terminal guidance system will activate and begin its search for a target. The missile's field of view or acquisition cone depends on the generation and type of guidance system. There are 3 generations of radar guidance systems in H4, each more capable than the last, and 2 generations of non-radar guidance systems (generally, infrared systems).

Anti-Ship Missile Guidance System Acquisition Cones

Guidance System Type	Search Angle	Large/Medium/Small Ship	Very Small/Stealth
Radar/1st	±15°	5 nm	2.5 nm
Radar/2nd	±30°	7 nm	3.5 nm
Radar/3rd	±45°	10 nm	5.0 nm
Non-radar/1st	±30°	5 nm	2.5 nm
Non-radar/2nd	±45°	7 nm	3.5 nm
Non-radar/3rd	±45°	10 nm	5 nm

If the missile was correctly directed, once the terminal guidance system activates, the target must be within its acquisition cone. If there is more than one target within the cone, the missile will choose a target based on its radar size.

The terminal guidance system will not necessarily choose the biggest target, but bigger targets have a greater chance of being attacked. A large-size ship is twice as likely to be attacked as a smaller one. The "Guidance System Lock-On Chances Table" gives the relative chances of a guidance system choosing one target over another within its acquisition cone. For radar and IR guidance systems, use the ship's radar signature (RCS). For laser or EO (electro-optical) guidance systems, use the ships' size classes.

Guidance System Lock-On Chances

Size Class	Lock-On Chance
Large	16
Medium	8
Small	4
Very Small	2
Stealthy	1

Example: a formation consisting of a (large) carrier, a (medium) cruiser, and 2 (small) destroyers will be rolled for on a D100. On a result of 1 to 16: the carrier is hit; 17 to 24: the cruiser; 25 to 28: the 1st destroyer; 29 to 32: the 2nd destroyer. If the result is higher, reroll.

If the same formation includes a carrier, a cruiser, and 2 destroyers with a reduced radar signature (such as the Arleigh Burke or Neustrashimyy classes, treated as very small), the hit chances will be 1 to 16: the carrier; 17 to 24: the cruiser; then 25 to 26 and 27 to 28 for the 2 escort ships. Any result above 28 is rerolled.

If there is no target in range, the missile will keep flying in the same direction, attacking the first target it encounters or until it runs out of fuel.

Note: the importance of terminally-guided missiles in naval combat should not be underestimated. They are the primary surface-to-surface weapon of most navies, and the primary threat ships must face.

Terminal guidance lets any unit receive target data via data link, radio, or any other kind of source, feed the information into the weapon, and then launch it. Dispersed units, with good coordination, can concentrate their firepower on a single point. Helicopters, or other reconnaissance units, can locate the target and then relay its coordinates to armed ships.

Using Helicopters for ESM Triangulation. Example: a surface ship formation suspects an enemy force is lurking to the north. They send 2 helicopters north, flying at medium altitude. They pick up a signal with their ESM, which identifies it as hostile, and triangulate its position. They send the target's approximate position to the formation, which can then launch SSMs at the enemy unit during the next planned fire phase.

Helicopters can use other detection systems, such as FLIR or radar, or other reconnaissance units may be used, such as submarines or even satellites, although communications with such units are more difficult.

5.3.14.1 Bearing Only Launch (BOL). Any inertially- or GPS-guided, terminally-guided weapon can be launched in "bearing only launch" mode. The weapon is programmed only to follow a direction or bearing and fly down its course with its guidance system activated immediately after launch. A bearing launch may be based on an ESM detection, a long-range CZ (convergence zone) sonar detection, or simple intuition.

In BOL mode, the seeker is activated after the missile has covered 10% of its range. As soon as it can, the weapon will attack the first target that comes within its range. If there are several targets in its acquisition cone, use the procedure in 5.3.14 to select the target the missile will attack. If there is nothing in the guidance system's detection field (the target may have moved out of the detection zone), the weapon will keep flying until it finds something or runs out of fuel.

Although BOL mode provides significant tactical flexibility, it also has drawbacks. First, since the guidance system is activated shortly after launch, the weapon will attack friend, foe, and neutral alike. Care must be taken not to hit your own ships with friendly fire, or a neutral tanker, with a salvo of BOL missiles. Remember that most modern warships carry a limited number of anti-ship missiles, and a player cannot afford to fire one or two at a sporadic ESM contact or a degraded firing solution.

Second, since the firing unit does not have good information on the target's location (otherwise why would it use BOL mode), the hit probability is reduced by 25% (multiply the modified hit chances by 0.75) to account for the fact that the weapon is not in the best position to reach the target.

5.3.14.2 Mid-Course Correction (-/M/----). This guidance-system capability lets inertially- and GPS-guided missiles receive course corrections after launch from the firing platform. This system is used with very long-range missiles, and lets a platform open fire on targets beyond the range of its own detection systems, with another platform then providing the necessary updates.

The unit providing the mid-course data must have radar line of sight to both the missile and the target. If line of sight is lost, or the guiding unit is destroyed, the attack becomes a bearing-only launch (BOL).

5.3.15 Reattacking Anti-Ship Missiles. Some newer anti-ship missiles have a built-in second-attack capability in their seeker's programming. If the missile locks onto a target but fails to hit it for whatever reason, it can turn around and try to attack it again. If an anti-ship missile has a reattack capability (noted in Annexes D or G), and has enough fuel, it can carry out several attacks against a ship. The second attack is resolved with the same hit chances as the first.

Missiles designed to carry out diving or popup attacks cannot reattack, even if they would otherwise be capable of it. The weapon is not designed to survive a diving attack that misses, which is why it crashes into the sea if it misses its target.

If a missile with reattack capability misses its target and there is another valid target within its detection system's field, the missile will move directly onto that new target and attack it normally. If there is no other target within the detection system's field, it will carry out a new attack against its original target. The maneuver consumes a large amount of energy, equal to 3 times its normal movement.

During the 2 movement phases following a missed attack, the missile will reposition to attack its original target by flying past it and executing a high-speed 180° turn. It will then close on the target and attack it during the third movement phase.

During the reattack maneuver, the missile may be engaged by the targeted ship's anti-aircraft defenses, but must be treated as a crossing target. Its range equals the missile's movement during one movement phase. The anti-aircraft defenses of other friendly ships cannot attack the missile because it will be too close to the targeted ship.

Example: a Russian Krivak-class frigate is attacked by a Harpoon IG missile. The missile has flown 35 nm and survives the ship's defensive weapons, but misses its target. The missile flies at 561 knots, or 2.3 nm/phase. Over the next 3 movement phases, it will maneuver to reattack, using up 20.7 (2.3 x 3 x 3) nm of its range. During the maneuver, it will be within range of the Krivak's AK-276 guns (3.5 nm), and its Osa-M [SA-N-4] SAMs (0.8-3.9 nm). They will, however, fire on the missile as a crossing target.

During the third movement phase of the maneuver, the missile carries out its attack normally. If it misses again, and has enough range remaining, it can attack once more.

5.4 AAM Guidance Systems

These systems are used to guide missiles launched in flight against other aircraft. Remember that AAMs launched from the low-altitude band have their range halved, as do AAMs fired from behind the 90° line of their target (anywhere in the rear hemisphere). An AAM fired from behind the target and from low altitude is therefore penalized twice, and has its range quartered.

5.4.1 Manual Command Guidance (Cmd). As with SAMs, ASMs, and SSMs, command guidance was the first AAM guidance method. The launching aircraft controls the missile's course and its closure with the target by sending it guidance instructions. The missile moves at maximum speed on a course leading it directly toward its target, changing course as needed to account for the target's movement. The aircraft firing the missile must be within radar line of sight of the target at launch and at all times until the missile impacts. If radar line of sight is lost or the launching aircraft is destroyed, the missile will miss its target. An aircraft can usually only control one missile at a time. Another missile cannot be launched and controlled until the first has aborted, been destroyed, or completed its attack on its target. Some aircraft can control more than one missile. This information is given in the remarks section of the annexes.

5.4.2 Infrared Homing (IRH). The missile is fitted with a guidance system that homes on heat sources, which is still the most reliable AAM guidance method. Its only limitation is that IR guidance systems must be relatively close to their target to lock onto it. After launch, the missile moves at maximum speed on a course leading it directly to the target. The only requirement to fire an IRH missile is that the target must be within visual line of sight of the firing unit at launch. IRH missiles do not need a fire director, and the only limit on the number of missiles fired at a target is the launcher's rate of fire.

Early IRH missiles could only attack a target from behind. They needed the heat from their target's tail exhausts directly within their forward "field of view" before they could lock on and be guided toward it. These missiles are marked with an "N" (Narrow-angle tail) in the type column of Annex H. When launched outside a dogfight, the attacking aircraft must be within an arc of ±30° centered on the target's tail. After launch, regardless of the target's movements, the missile is locked onto it.

The next generation of missiles was also limited to rear attacks, but had a wider field of view. This gave the attacking aircraft a better chance of being in an acceptable launch position. These are marked with a "W" (Wide-angle tail) in Annex H. When launched outside a dogfight, the attacking aircraft must be within an arc of ±60° centered on the target's tail.

The third generation of missiles uses cryogenically-cooled guidance systems sensitive enough to lock onto a target's heat signature from head-on. These are marked with an "A" (all-aspect), and they can be launched against a target from any angle.

The fourth generation of IR missiles, which is just entering service, uses an imaging infrared (IIR) guidance system combined with an advanced computerized signal-processing system. These missiles also have a swiveling seeker head which, when used with a helmet-mounted sight to aim it, increases the chances to hit.

The type of guidance system fitted to an IRH missile is used to determine an aircraft's chances of gaining a positional advantage during a dogfight.

5.4.3 Semi-Active Radar Homing (SARH). Once an aircraft has detected a target on its radar during an attack, it can lock onto or illuminate it (automatically, in the game) and launch a missile. The missile then begins seeking the radar signal reflected off the target. It homes at maximum speed in a straight line toward the target, correcting its course as needed to account for the target's movement. The target must remain within the radar's detection cone throughout its flight and until the missile impacts. If the radar is not aimed at the target, or if line of sight is broken, or if the aircraft that launched the missile is destroyed, the missile will miss its target. Any number of missiles may be fired at the same target. Only the aircraft that launched the missile can illuminate a target for its SARH missile. As with SARH SAMs, the missile's range against a non-maneuvering (usually unmanned) target is increased by 50%.

5.4.4 Passive Radar Homing (PRH). PRH AAMs use the targeted aircraft's radar signal as their guidance signal. This guidance system depends on the targeted aircraft leaving its radar on for the entire duration of the missile's approach, which is very unlikely if the targeted aircraft knows a PRH missile is inbound. It is possible to get an ESM detection of the target's radar at very long range, but the missile must move very fast, or the target will detect its approach and shut down its emitter.

A PRH air-to-air missile must have detected the target's emitter (an air- or surface-search radar, not an AI or fire-control radar) before launch, and the aircraft launching the missile must have an ESM detection of the target's radar and, at the same time, be within missile range.

After launch, the missile will move at maximum speed in a straight line toward the targeted aircraft. If the target shuts down its radar and does not turn it back on, the missile will automatically miss it. If it shuts down its radar and moves outside the missile's path (the missile has a radar field of view of ±60° centered on its heading), the target can safely turn its radar back on.

5.4.5 Inertial Guidance with Mid-Course Update and Terminal Active Radar Homing (I/M/TARH). This complex system first appeared with the US AIM-54 Phoenix and is now also used by the US AIM-120 AMRAAM, the French Mica, and the Russian R-77 [AA-12]. After detecting a target on its radar, the aircraft carrying the missile calculates its future position and fires the missile in inertial mode, aiming at that intercept point. If the targeted aircraft's course changes, shifting the intercept point, the fire-control system sends an update signal (a mid-course correction). Once the missile reaches the intercept point, it activates its own active guidance system, acquires the target, and then homes on its own for the remainder of its flight.

Since the only guidance the missile needs consists of occasional updates sent by the launching aircraft, an aircraft can control several missiles at the same time. The exact number of missiles fired simultaneously depends on the aircraft's fire-control system and will be given in the remarks section of Annex B.

Torpedo Generations Table

Torpedo Generation	Description	Chance to Hit
1	Active/passive seeker	40%
2	Improved active/passive seeker	60%
3	Advanced guidance system	75%
4	Digital guidance system	85%

5.4.6 Active-Mode Launch. Missiles fitted with terminal active radar homing (TARH) can be launched directly in active mode, in other words, with the terminal guidance system switched on from launch. Normally, the guidance system is only activated at the end of a long flight, and is used for final maneuvers close to the target. While radar guidance systems are effective, a missile at the end of its flight has spent its engine and has little fuel left. Consequently, even a missile with a well-locked guidance system can be defeated. Switched on from launch, the active guidance system, combined with the missile's full engine power, is harder to evade.

Annex H will show 2 ranges separated by a slash for missiles capable of active launch. The second range shown will be shorter than the first. These missiles will also have 2 ATA values, the second higher than the first. For an active-lock launch, the second number is used as both the range and the ATA value.

5.5 Torpedo Guidance Systems

Before and for nearly all of World War II, torpedoes were fired in a straight line, since they lacked any guidance system. By the end of World War II, they began to be fitted with miniature sonars that let them search for their target. The earliest torpedo guidance systems were optimized for attacking either submarines (ASW torpedoes) or surface ships (anti-surface torpedoes) only, while more recent weapons are generally dual-purpose and can attack both submarines and surface ships interchangeably. If there is an entry under the "damage vs sub" or "damage vs surface ship" column of Annex F, then the torpedo can attack that type of target.

5.5.1 Torpedo Sizes. Torpedoes have mainly evolved into 2 different size classes.

Small-size torpedoes answer the need to carry a number of them aboard ASW aircraft. This feature lets them be carried as the payload of ASW standoff weapons such as the US ASROC and the Russian Metel [SS-N-14]. These weapons are called "lightweight torpedoes" and are usually 324 or 400mm in diameter.

Larger weapons, with longer range and more powerful warheads, are today called "heavyweight torpedoes." They are usually 533mm in diameter, although the French have some 550mm weapons and the Russians have deployed 650mm torpedoes.

As guidance systems have improved, both lightweight and heavyweight torpedoes can be used to attack both surface ships and submarines. Players should know which type of torpedo they intend to use, since their size class will affect their performance.

5.5.2 Torpedo Generations. As torpedo guidance systems have advanced, their ability to find a target, resist decoys, and their chances to hit have improved. In H4, all guidance systems are classed by generation, which will affect the 3 capabilities listed above. Annex F will show, for

Torpedo Guidance Acquisition Cones

Acquisition Cone	Active Acquisition Range	Passive Acquisition Range
±60°	1,000 yards	500 yards
±60°	2,000 yards	1,000 yards
±75°	3,000 yards	2,000 yards
±75°	4,000 yards	3,000 yards

each torpedo, its guidance system's generation, its range, speed, and other important performance data. The guidance-generation table on page 5-9 gives the capabilities of each stage of torpedo guidance system development.

5.5.3 Acoustic Homing. These torpedoes use a built-in sonar to search for, acquire, and home in on their target.

As with any weapon with terminal guidance, acoustic-homing torpedoes are fired on a calculated intercept course toward a designated point. Once this intercept point is reached, the guidance system activates and begins searching for the target. If there are several targets within the weapon's acquisition cone, use the same procedure as in section 5.3.14 to determine which one the torpedo will attack. For active-homing torpedoes, use the target's size class on the guidance system lock-on table; for passive-homing torpedoes, use its acoustic signature. The only exception to this principle is when both submerged and surface targets are present in the torpedo's acquisition cone. If so, the torpedo will only attack the surface or submerged target whose pursuit was predetermined, a safety feature built into the weapon for the launching ship's protection.

Acoustic-homing torpedoes can be fired from torpedo tubes, dropped by parachute, or launched as the payload of an ASW standoff weapon.

5.5.3.1 Tube-Launched Torpedoes. Tube-launched torpedoes are ejected by a water or air charge ("positive ejection system"), or propel themselves out of a torpedo tube and move in a straight line along a predetermined heading, usually the precalculated intercept course, until the intercept point is reached.

To fire a torpedo from a torpedo tube, the player must launch his weapon on a fixed, predetermined heading. This may be an intercept course (which the fire-control system will supply) or any other direction the player wants. Modern torpedoes can turn up to 120° from their heading at launch. If a torpedo is wire-guided, the weapon's course can be changed at the player's discretion (see 5.5.4).

Nowadays, most torpedoes have 2 or 3 speeds for the player to choose from. The weapon's speed affects not only its range, but also its detectability. Before launch, the player must select the speed at which the torpedo will move until it acquires a target, at which point it will automatically accelerate to its maximum speed, unless the player changes its speed via wire guidance.

The player must also choose whether the torpedo will move above or below the layer, and where it will search, again above or below the layer. This matters because the thermocline will reduce the target-acquisition range by 50% if the target is not in the same part of the layer as the torpedo. The torpedo's depth can also be changed by the player if it is wire-guided.

Acoustic-homing torpedoes can be fired in a staggered fashion, but to avoid mutual interference, there must be at least 15° between the torpedoes' courses. Other options include spacing out the times the torpedoes are launched (by at least one engagement turn) or using the layer to shield the two weapons from each other. Mutual interference occurs when an acoustic-homing torpedo of the same type comes within twice another's passive acquisition range. When the first torpedo hears the active emissions ("pings") of the second (torpedo sonars are quite powerful), that signal is stronger than the echo of any submarine. The weapons then home on each other and stop searching for the originally intended target.

5.5.3.2 Parachuted and Standoff-Launched Torpedoes. Parachuted or standoff-launched torpedoes, after entering the water, conduct a helical (circular) search until they detect a target, then home in on it. The search circle is 1,000 yards (0.5 nm) in diameter, centered on where the weapon entered the water. "Helical" means the torpedo also changes depth as it searches, since the targeted submarine's depth is usually unknown at the time of firing. When an ASW torpedo conducts a helical search, it will spend the first half of its running time above the layer and the other half below it. However, if the submarine's depth is known, the weapon can be set, as needed, to conduct its circular search above or below the layer.

While the torpedo conducts its search, if another acoustic-homing torpedo of the same type is within twice the first one's passive acquisition range, it will "see" the second one, whose active sonar will give a stronger signal than the echo of any submarine. If mutual interference occurs, the weapons will try to home on each other rather than on the originally intended target. These torpedoes, therefore, to prevent any risk of mutual interference, must be separated by at least twice their passive acquisition range.

5.5.4 Wire-Guided Torpedoes (Wire-G). The only difference between acoustic-homing torpedoes and wire-guided torpedoes is that the weapon's spool (called a "unit" by submariners) pays out a thin cable connecting it to the launching submarine's fire-control system. This lets the submarine change the torpedo's course, its speed (if variable), its depth, the intercept point, and, on the most advanced models, receive target information back from the weapon. All generations of acoustic-homing torpedoes can also be fitted with wire guidance.

The number of wire-guided weapons that can be controlled simultaneously depends on the fire-control equipment carried by the launching submarine. This is described in section 4.4.9, sonar tracks and fire-control systems. If the wire is not cut, the firing submarine can manually control the torpedo and carry out several attacks on the target, or steer it through an acoustic countermeasures environment.

"Dual-wire" guidance systems, called TELCOM in the US Navy, are an improved version of wire guidance in which information can flow in both directions. Not only can the firing submarine change what the torpedo does, but the weapon also feeds the submarine information about its own position and the target's location, if detected.

Wire-guided torpedoes are both a blessing and a curse. They can be controlled by the firing submarine after launch, but only if the wire remains intact. To keep the wire from being cut, the launching platform must observe strict maneuvering limitations.

• At launch, there is a 20% chance the wire breaks, regardless of the submarine's maneuvers.
• After launch, if the firing platform changes depth, changes course by more than 45° from its heading at launch, or exceeds 10 knots, there is a chance the wire will be cut. Combining these effects increases the chance of the wire being cut. A wire-integrity check must be made every engagement turn when one or more of these conditions is met. The chances of a wire breaking are given on the Wire-Guided Torpedo Wire Break Table.

Wire-Guided Torpedo Wire Break Table

Platform Speed	Speed	Speed/Turn or Depth Change
10 knots	0%	15%
11-15 knots	25%	60%
16-20 knots	50%	80%
21 knots and up	100%	100%

• A launching platform can also deliberately cut the wire, which is required if the player wants to reload that tube (the spool remains in the launch tube). This can be done at any time during the torpedo's run, and it is possible to order it to switch to active search and/or change its speed before the wire is cut and the link is lost.

If the wire is broken, the attack is resolved using the "non-wire-guided torpedoes" section of the "homing torpedo attack table" on page 6-30.

Parachuted wire-guided torpedoes can only be launched from a hovering helicopter. The chances of the wire breaking at launch are the same as for a tube-launched weapon. If, after launch, the helicopter exceeds 50 knots, the wire is automatically broken. Wire-guided torpedoes cannot be used as the payload of an ASW standoff weapon.

5.5.5 Wake-Homing Torpedoes (Wake-H). Wake-homing weapons detect the turbulent wake left by a passing ship, then follow it and climb the cone back to its source. They are used like any other acoustic-homing torpedo, but they are not affected by acoustic countermeasures.

There is, however, a possibility of decoying them if another ship passes through the targeted ship's wake. The size of the crossing ship determines the chances of decoying the weapon. Treat a small ship as 1st-generation countermeasures, a medium ship as 2nd-generation countermeasures, and a large ship as 3rd-generation countermeasures. If the weapon is successfully decoyed, it will then lock onto the ship generating the countermeasures.

See section 6.7.7 for more information on decoying torpedoes.

5.5.6 Acquisition Ranges. The torpedo guidance generations table gives the acquisition range for each generation of torpedo guidance system. These ranges can be modified by the following conditions.

5.5.6.1 Anechoic Coatings. Submarines coated with acoustic tiles reduce active acoustic detection system range by 50%. For example, a US Mk 48 Mod 4 (3rd-generation heavyweight weapon) trying to actively acquire a submarine with an anechoic coating has its range reduced from 3,000 yards to 1,500 yards.

5.5.6.2 Target-Generated Noise. The passive acquisition ranges given on the torpedo guidance generations table are for quiet targets. If the target has a higher or lower noise value, the passive acquisition range value must be multiplied by one of the following values:

Noise Level	Multiplier
Very Loud	2
Loud/Noisy	2
Quiet	1
Very Quiet	1/2
Extremely Quiet	1/4

5.5.6.3 Reverberation. Water shallower than 600 feet (100 fathoms) is called "shallow water" by submariners and ASW operators. Sonar propagation characteristics in water of this depth are very different from "open ocean" sonar conditions. This affects sonar detection, the deployment of detection systems, and certain acoustic-homing weapons.

Depth charges and anti-submarine (ASW) mortars are not affected by shallow-water effects. This is one reason European navies, which operate much more in shallow water than the US Navy, still use this type of weapon.

Shallow water and under-ice water are high-reverberation environments, where reflections off the sea floor and off the sea surface or the underside of the ice create many false echoes. These echoes can confuse a torpedo's seeker. If an acoustic-homing torpedo is fired in shallow water, in the marginal ice zone, or under pack ice, reduce the torpedo's active acquisition range by 50%.

If the torpedo's guidance system is noted as having an "under-ice" or "shallow-water" capability, reduce its active acquisition range by 25% instead of 50%.

5.5.7 Dual-Speed Torpedoes. Some torpedoes have two, or sometimes even three, programmable speeds. A slow speed that gives greater range, a medium speed for weapons with three optional speeds, and a high speed used for the actual attack. Players may choose to fire a torpedo at whichever programmable speed they choose, with reduced range if they select the higher speeds. Wire-guided torpedoes can be ordered to change speed as long as their wire remains intact.

If the torpedo is fired at slow or medium speed, it will automatically accelerate to attack speed as soon as it acquires a target.

5.5.8 Quiet Torpedoes. Some multi-speed torpedoes, due to their propulsor's advanced design and their propulsion unit's sound insulation, are quiet or sometimes even very quiet at their slowest programmable speed. This considerably reduces the torpedo's detection range by the targeted unit and significantly affects its ability to evade or decoy the attacking torpedo.

When a torpedo accelerates to high speed, its engine generates more noise and its propulsor begins to cavitate, increasing its detectability. However, even a torpedo at its highest speed, fully cavitating, will not generate as much noise as a large ship. Consequently, speed and cavitation modifiers do not apply to torpedoes. Instead, a torpedo at any programmed speed above its slowest is treated as a noisy contact for detection purposes. Once detected, a torpedo must be classified as such. The torpedo classification procedure is the same as for identifying ships and submarines (see section 4.4.8).

Chapter Six – Combat

This chapter covers resolving the various types of attacks carried out by naval and air platforms against their targets. It is organized into sections by attacking platform type, then by target platform type. For example, under section 6.3, air attacks, there are subsections covering attacks against other aircraft (air-to-air combat), against surface ships (anti-surface warfare), and against submarines (anti-submarine warfare).

Refer to the annexes for the data of the various weapon systems used (or to the completed ship or aircraft reference sheet). The annexes will give the weapon's characteristics, such as range, speed, the damage it inflicts, and, for some annexes, the percentage chance to hit. For other weapons, hit probabilities are given by the tables in the appropriate section of this chapter. A weapon's hit percentage is sometimes modified by the rules applicable to the type of combat described within those sections. A roll of two D10s, read as a D100, is compared to the modified hit probability.

The die roll must be less than or equal to the modified hit probability for the attack to succeed.

6.1 Firing Solutions

All naval weapons are directed by information about where the target will be when the weapon reaches it. This "solution" comes from discovering and tracking the target's position, calculating its course and speed, and anticipating its future movement. For short-range weapons, or weapons that remain under constant control from launch to impact, a good firing solution is not essential.

For long-range weapons, or inertial weapons with a terminal guidance system, anticipating the target's position and future movement is vital. For some cruise missiles, there can be more than half an hour between missile launch and activation of its guidance system. If the target is not where the solution says it should be, all the missile's guidance system will see is water as far as the eye can see.

6.1.1 Bearing-Only (BOL) Anti-Ship Missile Attacks. Anti-ship missiles with inertial or GPS guidance, coupled with a terminal seeker, may, if necessary, be launched in "bearing only launch" mode (BOL — see 5.3.14.1). One of the drawbacks of a BOL attack is that it is based on bearing information alone. Without range information, the target's course and speed can only be estimated from how fast the bearing changes over elapsed time. For over-the-horizon anti-ship missile attacks, this lack of target information reduces the hit chances by 25%. Consequently, multiply the hit chances, after accounting for all countermeasures, by 0.75.

6.1.2 Passive Target Motion Analysis (TMA). In submarine warfare, passive firing solutions, or target motion analysis (TMA), are the normal mode of operation. This is a mathematical procedure that uses the detecting platform's course, its speed, and a series of bearings on the contact to build a series of estimates of the contact's range and speed. Each estimate is (ideally) more accurate than the one before it, and is eventually accurate enough to predict the contact's next bearing. This tedious procedure, which can take a long time, generates a lot of frustration. It is not unusual to have several completely wrong starting points that lead nowhere and require starting over.

Of course, active sonar solves this problem by providing range, but at the cost of revealing the location of the emitting submarine or ship.

In Harpoon 4, TMA solutions are graded as good, fair, poor, or bearing-only (BOL). The quality of the TMA solution, at the moment of firing, will affect the hit probability of standoff ASW weapons (section 6.4.3.2) and of homing torpedoes (section 6.5.2.2).

On each turn contact is maintained by passive sonar, the detecting player may try to calculate a passive TMA solution. The chances of success depend on the range from the contact to the detecting platform. A short or close range is better than a long one.

Begin by measuring the range to the target and finding the row on the TMA Solution Quality Table (page 6-3) that includes that range. There will be a set of values for whether the solution is good, fair, poor, or bearing-only (BOL). These percentages, cumulative each turn, represent the chances of calculating a firing solution.

Take the number of tactical turns during which the platform has detected the target and multiply it by the value given for each solution level for that range band. Add to the result any applicable modifiers for the detection system type and the target's maneuvers. This will give a set of values for each of the four solution grades. Roll 1D100 and see whether the result is less than or equal to one of the various solutions' values/percentages. The lower the die roll, the better the result. The solution calculated that turn will be the one with the lowest value that the roll is still less than or equal to.

Example: a Trafalgar-class SSN detects a Victor III-class SSN at 4.5 nm with its 2046 passive sonar towed array, and begins calculating a TMA solution. Checking the 2.6-5.0 nm row on the TMA Solution Quality Table, the TMA solution probabilities after this first turn are:

Good: (20% x 1) + 20% = 40% Fair: (30% x 1) + 20% = 50% Poor: (40% x 1) + 20% = 60% Bearing-only (BOL): (50% x 1) + 20% = 70%

Rolling a 55 on his D100, the Trafalgar has a poor solution after this first turn.

On the second turn, the Victor III is at 4.2 nm, and so has not changed range bands, giving now:

Good: (20% x 2) + 20% = 60% Fair: (30% x 2) + 20% = 80% Poor: (40% x 2) + 20% = 100% Bearing-only (BOL): (50% x 2) + 20% = 120%

In other words, the Trafalgar automatically has at least a poor solution. The player rolls 78, which gives him a fair solution.

A Foreword on Tactics. Knowing that a deadly enemy is somewhere in the vastness of the sea can be very discouraging, since it leaves the player with the impression that there is no starting point and nowhere to find the enemy before he finds you. Several general rules can prove useful:

First, learn the rules of the game. In particular, know how detection systems interact and are affected by the environment. Know how detectable you are, not just in general terms, but in knots, miles, and meters. This will tell you how much air and ocean you have to control. If you don't control it, your opponent gets a free shot.

Example: I once saw a player commanding a surface force, in an area where a submarine was known to be present, charging his formation ahead at 30 knots (his maximum possible speed). I told him his sonar would be "somewhat degraded," i.e. completely deaf, but he continued anyway. The Russian submarine, at a good distance, heard the racket, quickly maneuvered (without interference) into position, and then fired a salvo that sank three ships without warning.

Second, don't cower. Many players head toward their destination with all their radars and sonars switched off, hoping they won't be detected. EMCON (emissions control) is a good idea, but it's only a tool. Some players have left their radars off even after being detected and attacked. Not only can this be a less effective tactic, it also cedes the initiative to the enemy.

The answer is a proactive search for the enemy, but in a way that doesn't reveal your forces or your intentions. The best way to do this is to use your helicopters. The third rule is to use your helicopters as much as possible to conduct searches. They are fast compared to surface ships, well equipped with detection systems, and a medium-size ship formation can easily deploy half a dozen of them. Deploy them in a reconnaissance screen, or advancing in pairs along a threat axis. They can quickly conduct a passive search over large areas without exposing the surface force.

Submarines should obviously operate passively, but players may think that at some point, it's fine to use active sonar and active periscope radar. Real submarines very rarely use active mode, and when they fire a weapon or take other noisy actions, they always have a clear, specific plan for getting back to cover.

Carriers are no picnic either. Managing an air group and launching an attack can be a full-time job for an air operations officer, and I recommend designating a player for that role. A carrier is also a top-priority target for the other side, which tends to force its owner into a defensive mindset. Carriers are offensive weapons, even when defending themselves. Everyone thinks of setting up combat air patrols (CAP), but what about sending a handful of interceptors racing forward along the axis the threat is coming from? If you can pinpoint where the enemy is coming from in time, a handful of interceptors doesn't just have to find the attack — it can break it up well beyond CAP radius.

On the 3rd turn, if the Trafalgar still manages to maintain contact and the Victor III does not maneuver, the chances of a TMA solution will be: good: 80%, fair: over 100%. As a result, the Trafalgar will now automatically have at least a fair solution, and an 80% chance of a good solution.

Once a particular solution quality has been achieved, it will not degrade if the player rolls lower on a later turn. It stays at the same level as the previous turn. It is only when the target changes course and/or speed, or when the detecting platform loses contact for too long (see 6.1.3 for details), that the solution quality degrades.

6.1.3 TMA Limitations. Beyond a range of 20 nm, the bearing rate is so low that passive TMA techniques cannot provide a reasonable solution. On the other hand, active sonars, if capable of detecting a submarine beyond 20 nm, can still provide a solution. For CZ detections, the only data available to passive sonars is bearing. Range, course, and speed are almost impossible to deduce. For active sonars, both bearing and range are provided, wherever the target is within the CZ, but neither course nor speed.

If contact is lost for a long enough period, the TMA solution clock must be reset to zero and the solution calculation must be started over entirely. The number of consecutive tactical turns without contact that triggers this depends on the target's range and is given by the Contact Loss Table below.

Contact Loss Table

Target Range (nm)	Loss Criterion (tactical turns)
0-2.5	1
2.6-5.0	2
5.1-10.0	3
10.1-20.0	4

Example: if the Trafalgar-class SSN from the previous example has a "fair" solution on the Victor III after 3 tactical turns, then fails to maintain contact for the next 2 tactical turns, the Trafalgar will lose its fair solution and will have to restart the TMA procedure from scratch.

6.2 General Combat Procedures

Unless otherwise noted in a ship class's remarks section, each weapon (except guns) can only fire once (missile, torpedo) per tube or rail. Guns can fire multiple times, and some gatling guns can fire on the order of 100 rounds (in short bursts) per engagement turn. Other weapons with multiple barrels (such as ASW mortars) fire all their tubes simultaneously, in a single salvo, to cover a large area. For gunfire, the number of shells fired is always factored into the hit percentage and the damage value. If the target is hit, this means quantifiable damage was inflicted by the shots fired over the last 30 seconds (one engagement turn).

Unless the rules or annexes specifically state otherwise, all weapons automatically reload from below-deck magazines. If the annexes note that the weapon must be manually reloaded, assume it takes 2 tactical turns to reload a mount (see section 5.2, rates of fire) or a weapon if the mount holds missiles or torpedoes.

Unless additional reloads are noted in a particular ship's remarks section, the only ammunition available is what is given on the weapon lines for each mount.

TMA Solution Quality Table

Range Band	Target Range (nm)	Good	Fair	Poor	BOL
Short	0-2.5	30%/turn	40%/turn	50%/turn	Detection
Medium	2.6-5.0	20%/turn	30%/turn	40%/turn	50%/turn
Long	5.1-10.0	10%/turn	20%/turn	30%/turn	40%/turn
Very Long	10.1-20.0	5%/turn	15%/turn	25%/turn	35%/turn

TMA Solution Modifiers

Modifier	Short/Medium	Long/Very Long
Passive sonar	—	—
Passive ranging sonar	+20°	+10°
Active sonar	+40°	+20°
Periscope	+50°	+50°
Laser/radar range finder	+30°	+15°
Target course change (+20°)	+60°	+60°
Target speed change (+5 knots)	−25°	−25°

(Note: modifiers are added to/subtracted from the percentage chances above, per solution type, following the source table's layout.)

6.2.1 Weapon Firing Arcs. The weapon line gives the firing arc for each mounted weapon. If the target is not within the weapon's firing arc, the weapon cannot be used. The only exceptions are missiles using waypoints and torpedoes with the ability to turn up to 120° from the axis of the tube they were launched from.

6.2.2 Mounted Weapon Malfunctions. When rolling to resolve a shot, a result of 00 (on 1D100) indicates a system failure or breakdown, and the firing mounted weapon is out of action (critical failure). This simulates the occasional misfires that occur during extended weapon use.

For guns and related weapons, the weapon is out of action until repaired (see section 7.4). For missiles, the seeker has failed. If it has no seeker, the launch control system is inoperative. In every case, do not roll 1D10 for a magazine explosion (fire).

6.2.3 Weapon Danger Zone. If a gun or missile shot misses the targeted surface ship, other surface units in the immediate vicinity may be hit instead. Since artillery fire pledges allegiance to no one, friend and foe are equally vulnerable. For gunfire, if a unit is located within a ±10° cone of the line of fire and within ±10% of the range separating the target from the firer, it may be attacked.

Find the number of surface units within the danger zone and randomly determine by die roll which is the new potential target. Minimum and maximum ranges can alter the size of the danger zone. Halve the hit percentage after all modifiers have been applied, and roll to see if the weapon hits that target. The randomization is done weapon by weapon. Only one unintended attack per weapon is possible.

For missiles, if the original target is missed, how many other targets the missile can see depends on its detection system and the generation of its guidance system. Choose a target using section 5.3.14 and resolve an attack against that unit normally. Furthermore, if a missile has a reattack capability (section 5.3.15), the original target may still face another pass by the weapon.

6.2.4 Resolving Anti-Ship Missile Attacks. Since anti-ship missiles can be fired from ships, submarines, aircraft, and land-based launchers, and because all anti-ship missile attacks are resolved the same way, they are all covered here.

Most anti-ship missiles use radar guidance systems, while a few use IR guidance systems. Almost all warships carry jammers and decoys designed to disrupt these guidance systems and keep them from locking on. All anti-ship missile guidance systems in the game have values corresponding to their level of technological development, grouped into "generations." Early missiles, like the P-15 Termit [SS-N-2A Styx], are first-generation weapons and have little or no ability to overcome electronic countermeasures (ECM). Second-generation missiles, like the MM38 Exocet, have more advanced guidance systems incorporating home-on-jam (HOJ) capability to counter early onboard jammers. They also have some resistance to decoys. Third-generation missiles, like the Harpoon IC, have even more capable guidance systems. Thanks to digital processors and sophisticated counter-countermeasures software, they have greater resistance to onboard ECM and a better chance of recognizing a genuine target amid the electronic fog.

Like anti-ship missile guidance technology, defensive ECM also follows generational development. Chaff decoys' radar cross section has grown larger, deployment patterns have become more precise, and the most advanced decoys are self-propelled. Jammers have become faster, thanks to automation, and smarter, relying more on seducing the missile's guidance system than on saturating it with electronic noise.

An anti-ship missile's chances of hitting a ship depend on its guidance system's ability to pit its electronic wits against the ship's appropriate defensive ECM. A first-generation missile attacking a ship fitted with first-generation ECM has a good chance of overcoming the deception. If the missile has a third-generation guidance system, it won't even notice the ship's first-generation ECM. Conversely, a ship fitted with third-generation ECM will be practically immune to a first-generation missile, but a third-generation missile will have a decent chance of getting through its electronic defenses.

The missile's chances to hit also depend on the size, or radar cross section (RCS), of the defended ship. Since it's easier to create fake small targets than large ones, a small ship is easier to defend.

When a missile attacks a target, use the anti-ship missile attack tables. There is a table for each signature, from large to stealthy. On the table matching the target's signature, find the row for the ship's ECM generation, then the row for the missile's guidance system generation. Refer to the column describing the type(s) of ECM: jammers, decoys, or both. The number in that column is the missile's chance to hit its target. For IR-homing weapons, use only the decoys column.

Example 1: a Chinese HY-2 is fired at an O.H. Perry-class frigate. The HY-2 is an improved copy of the Russian P-15 Styx, and belongs to 2nd-generation weapons. The Perry has a small signature and carries 3rd-generation jammers and decoys. Using the small-target signature table, the attacking player finds the 3rd-generation ECM row, then the 2nd-generation missile row, then refers to the jammers-and-decoys column. The missile's chance of hitting the ship (if it survives the defensive weapons) is 33%.

Example 2: a submarine fires a salvo of Russian P-500 Bazalt [SS-N-12 Sandbox] anti-ship missiles at a US carrier, also fitted with 3rd-generation jammers and decoys. The P-500 Bazalt is a 2nd-generation anti-ship missile. Using the large-target RCS table, following the 3rd-generation ECM row, then the 2nd-generation guidance system row, then referring to the jammers-and-decoys column, gives a 72% chance to hit the target.

Example 3: a large merchant ship is attacked by an air-launched AM.39 Exocet. The merchant has no electronic defenses, and the Exocet is a 2nd-generation missile. Using the large-target RCS table, following the 2nd-generation guidance system row for any ECM generation (which all give identical scores), then referring to the "Missile Ph" column, gives an 80% chance to hit.

6.3 Air Attacks

An aircraft can carry a wide variety of weapons letting it attack other aircraft, ships, submarines, and land targets. While World War II clearly demonstrated that aircraft were a threat, the proliferation of smart weapons and the advent of stealth have made defending against this threat even harder.

6.3.1 Aircraft Values. Aircraft have 2 air-to-air (ATA) defensive values. The first is used when the aircraft carries a full external payload. The second is used when the aircraft is lightly loaded or unloaded. Aircraft defensive values are based on factors such as relative age, wing loading, and thrust-to-weight ratio.

Air-to-air missiles and guns also have values assigned on the same scale, called offensive ATA values. An air-to-air weapon's offensive value is based on its hit probability and its lethality if it hits its target.

As long as the aircraft's external stores consist of air-to-air ordnance (e.g. missiles, gun pods), treat it, for purposes of its full-load/light-load-or-unloaded value, as only lightly loaded (exception: aircraft carrying 4 or more AIM-54 Phoenix or R-33 [AA-9 Amos] must be treated as fully loaded). The gun value is not affected by the aircraft's load. Some aircraft, usually those designed to perform only one type of mission, have the same value whether fully loaded or unloaded. The most common example is the pure interceptor, like the MiG-25 Foxbat, which can only carry air-to-air weapons. At the other extreme, there is the B-52, whose ATA value is so poor that dropping its external stores would have no effect. There are also aircraft that carry no external load at all.

For example, a MiG-19 Farmer has a defensive ATA value of 3 when armed only with Atoll AAMs and nothing else (except its internal gun). When carrying jettisonable external tanks and 250 kg of bombs, its defensive ATA drops to 1.5. To regain its light-load/no-load ATA value, the aircraft must drop its air-to-ground ordnance and its external tanks. It can keep any number of air-to-air missiles. The MiG-19 in the example above would have to drop its bombs and external tanks to see its ATA value return to 3. It might also have to use its internal gun in a dogfight.

An aircraft's ATA can also be affected by electronic/IR countermeasures such as chaff, flares, and jamming pods. If an aircraft incorporates stealth technology and has a very small or stealth radar signature, this will also affect the performance of an AA missile or gun system against it. See the ATA modifier list for the ATA bonus applicable based on ECM/IRCM generation and degree of stealth.

6.3.2 Aircraft Weapons. Standard military load-outs for each aircraft type are given in Annex B. However, these loads are not an exhaustive list. If players want their aircraft to carry a load different from those given in Annex B, they must find a photograph or other reference showing that the aircraft can actually carry the desired configuration's load. Be careful that the ordnance making up its load is appropriate for the country operating that aircraft type. For example, a Russian MiG-23 can carry R-23 [AA-7 Apex] and R-60 [AA-8 Aphid] missiles, but Libyan MiG-23s can only carry K-13 [AA-2 Atoll] missiles.

Since aircraft can only carry a limited number of weapons, players must keep track of the ordnance used. For aircraft guns, whether internal to the fuselage or mounted in external pods, each gun has ammunition for 4 fire phases. Internal or podded guns can open fire simultaneously as 2 separate attacks, or one after another in different phases to conserve ammunition.

6.3.3 Air-to-Air Combat. Air combat is resolved in 30-second engagement turns. Aircraft movement is divided into 2 fifteen-second movement phases, and they move as described in section 3.3. Air-to-air combat in Harpoon 4 can take the form of long-range missile combat or close-in air combat, or "dogfighting."

When an aircraft is in position to fire against a target within range of its guns or missiles, subtract the target's defensive ATA value from the attacking weapon's value. The resulting number is looked up on the Air-to-Air Combat Resolution Table to determine the % chance to hit (and destroy). This % may be altered by the modifiers noted below the table, by ECM/IRCM systems carried by the targeted aircraft, or by stealth considerations. As with anti-ship missile attacks, air-to-air missile guidance systems and electronic defenses are classed by generations. The effects of an attack occur simultaneously, after all attacks in the phase have been resolved.

Example: a MiG-23 fires a 2nd-generation R-23 [AA-7 Apex] (value: 4) at a Tornado GR.1 (light-load value: 3). The Tornado carries no internal defensive jammer, but frequently carries a 2nd-generation Sky Shadow defensive ECM pod and a BOZ chaff pod (2nd-generation decoys). Comparing the missile's guidance system generation with the jammers and decoys on the aircraft countermeasures table gives a +1 for the jammer and a +1 for the decoys, for a defensive value of 5.

Subtract the defensive value (5) from the missile's offensive value (4), giving a result of -1, which gives a 20% chance of hitting its target.

Air-to-Air Combat Table

Value Difference	Air Combat %	Value Difference	Air Combat %
−4.0	01%	+1.0	40%
−3.5	03%	+1.5	45%
−3.0	05%	+2.0	50%
−2.5	07%	+2.5	55%
−2.0	10%	+3.0	60%
−1.5	15%	+3.5	65%
−1.0	20%	+4.0	70%
−0.5	25%	+4.5	75%
−0.0	30%	+5.0	80%
+0.5	35%	+5.5	85%

Air combat modifiers:

• If the attacker is at least one altitude level above or below the targeted aircraft and is not using a snap-up/snap-down capable missile: +1.0 to defensive ATA.
• If the target is moving faster than 8.3 nm per engagement turn, or 4.2 nm per phase (1,000 knots): +1.0 to defensive ATA value.
• If an anti-ship missile is conducting evasive maneuvers during search/guidance: +1.5 to the missile's ATA.
• Unmanned target (e.g. a drone or cruise missile): ATA = 0.5.
• A manned aircraft taking no evasive action (surprised, in formation): ATA = 0.5.
• The target is taking off, landing, or hovering: ATA = 0.0.
• The target has ECM/IRCM: see the table below for the defending aircraft's ATA modifier.
• If the target is flying sea-skimming (V Low altitude band), there is a +1.0 modifier to the target's ATA if attacked by a sea-skimming-capable SAM, and +4.0 to the target's ATA if attacked by a SAM that cannot engage sea-skimmers.
• The targeted aircraft has a very small or stealth RCS: see the table below for the defending aircraft's ATA modifier.

6.3.3.1 Air Combat Restrictions. There are cases where air combat cannot occur, or where one of the aircraft is at a disadvantage.

• Aircraft taking off or landing cannot attack or defend themselves. They have an ATA of 0.0, which can be improved by jammers and decoys.
• Aircraft cannot shoot down surface-to-air (SAM) or air-to-air (AAM) missiles because of their small size. They can engage surface-to-surface (SSM) and air-to-surface (ASM) missiles.
• Aircraft cannot attack more than one aircraft with one weapon type in a phase. There are a few exceptions to this rule: some aircraft can fire more than one missile at more than one target. Annex B notes which aircraft have multiple-launch capability. Aircraft can fire their gun or launch their missiles during a phase, but not both.
• Unless armed with snap-up/snap-down missiles, an aircraft can only attack a target one altitude level away from its own. For example, an aircraft at low altitude can only attack a target at very low, low, or medium altitude, and not at high or very high altitude.

6.3.3.2 Missile Combat. Aircraft can attack each other with medium- or long-range air-to-air missiles without engaging in a dogfight. The attacking player may declare he is firing a missile at the target, if it is within the missile's range and altitude limits given in Annex H.

On the phase it is fired, a missile does not move, since it has just been launched. Afterward, on each aircraft movement phase, the missile will move toward its target. The missile's range is measured from the geographic point where it was fired to the missile's current position. If a missile exceeds this range without reaching its target, it automatically misses.

Once the missile reaches its target (during the movement phase), the attack is resolved using the air-to-air combat table.

The number of missiles fired by an attacker depends on the type of aircraft firing and the missiles' guidance system. Section 5.4 covers the various guidance system types and their capabilities. The remarks section of Annex B will note whether an aircraft can attack more than one target with missiles during the same phase.

If the guidance system allows it, an aircraft can fire up to 2 missiles at the same target during a 15-second fire phase.

"All-aspect" missiles can be fired at a target from any angle. Missiles that are not all-aspect must be fired toward the rear of the target aircraft, within a narrow tail angle of ±30° or a wide tail angle of ±60°, centered on its flight path.

6.3.3.2.1 Evasive Maneuvers. During the movement phase of an engagement turn in which an AAM or SAM reaches the aircraft, the aircraft cannot do anything but attempt evasion. By combining the release of chaff and flares with evasive maneuvers, an aircraft can reduce the missile's chances to hit. The rules automatically assume that an aircraft targeted by a missile will begin an evasive maneuver, and the missile's hit chances already factor this in. If the player wants the aircraft not to maneuver, treat it as having a defensive ATA value of 0.5.

An aircraft attacked by a missile cannot launch or drop anything onto a target during that phase. Any SARH-guided or command-guided missile the targeted aircraft was controlling will miss its target and be lost.

If the targeted aircraft was designating a target for an SALH weapon, or was maintaining the link with a controlled EO/IR weapon, line of sight is lost and the weapon's hit chances are reduced to 1/4 of their normal value.

The only action a targeted aircraft is permitted to take is to be able to drop all or part of its external ordnance, if it wants to change its ATA value from "full load" to "lightly loaded." Ordnance dropped this way automatically misses its target.

If the aircraft survives the attack, its pilot rolls 1D6 and refers to the following table:

1: turn left 90° 2: turn left 60° 3: turn left 30° 4: turn right 30° 5: turn right 60° 6: turn right 90°

During the movement phase of that engagement turn, the aircraft must carry out the maneuver indicated by the die roll. It also slows down by 1D6 x 50 knots. If this roll forces the aircraft below its stall speed (cf. 3.3.2, Speed), reduce the aircraft's altitude by one level and its speed to its stall speed. If the aircraft was at very low altitude and must descend a level, it crashes.

6.3.3.2.2 Missile Failure Roll (optional rule). Air-to-air missiles are notoriously unreliable. Buffeted by turbulence at speeds above 600 knots, subjected to the stress of multi-G turns, it takes a bit of luck for an AAM to work properly. After a player has declared which type and how many missiles he is firing that phase, he must roll 1D10 for each one. If the roll is a 9 or a 0 (10), the missile leaves its rail but does not ignite. This may seem harsh, but historically, AAM failure rates have been consistently high.

6.3.3.3 Dogfighting. The classic dogfight involves maneuvering aircraft using short-range missiles and guns to attack each other. Any aircraft that ends its movement within 5 nm of another aircraft at the same altitude level may declare that it is engaging that aircraft in a dogfight. The other aircraft may choose to engage or to break off and flee.

Special weapon rules apply during a dogfight. All radar-homing air-to-air missiles, unless Annex H states they can be used in a dogfight, have their ATA value halved (round ATA to the nearest 1/2) when fired at an aircraft that has itself declared it wants to dogfight the firing aircraft. Guns, whether internal or in external pods, can only be used against air targets during a dogfight.

Aircraft involved in a dogfight do not move normally. If only one aircraft declares a dogfight (and the other tries to flee, or is a missile that cannot maneuver), then the attacking aircraft automatically moves along with its target. If both aircraft decide to dogfight, then both move randomly on the playing surface. A dogfight moves 1D6/3 nm each engagement turn, in a direction of 1D6 x 60°. The dogfight ends for each aircraft at (1D6/3) − 1 altitude level(s) lower than where it started.

Aircraft engaged in a dogfight use afterburner, if fitted, and otherwise must use full military power. Players must keep track of how long the fight lasts, so they can tell how much fuel their aircraft has used during it. Furthermore, players engaged in a long fight may want to know how long it can last before they must break off and return to base. Section 3.3.6 covers fuel consumption.

Any number of aircraft can take part in the same dogfight. New aircraft can join a dogfight already in progress at any time. If a transiting aircraft enters a dogfight and is engaged by any aircraft already involved, the dogfight moves along with the transiting aircraft. In other words, dogfights are "sticky." 2 dogfights will merge if they touch. So 2 dogfights + 1 dogfight and a chase = 1 dogfight.

A dogfight lasts until all units on one side are destroyed, or until both sides break off and leave. It is possible to have a large dogfight combining multiple engagements: A engages B, while C and D engage A, and E engages C. The only restrictions on dogfighting are the 5 nm range and being at the same altitude level. An aircraft can use a dogfight as both an offensive and a defensive maneuver.

Example: an aircraft is being chased by an interceptor armed with long-range missiles. The interceptor is in range and will fire next turn. The first aircraft chooses to slow down, which puts it within dogfight range of its pursuer. The first aircraft chooses to engage the dogfight, and it's a whole new game. Will the interceptor try to open the range so it can use its long-range missiles, or will it engage in a dogfight, which means reduced capability for its missiles?

Procedure: when a dogfight begins, place a counter on the playing surface centered between the aircraft taking part. Remove those aircraft from the playing surface. They are considered to be maneuvering violently within a 10 nm zone centered on the counter. Their exact position is undetermined. All distances to an aircraft involved in a dogfight must be measured from the counter. If one of the aircraft involved is not fighting, the counter moves along with it. If all the aircraft are maneuvering, the dogfight moves randomly. On leaving a dogfight, position and altitude are determined randomly.

By definition, an aircraft involved in a dogfight has no precise position on the playing surface, and in reality changes position rapidly, mixing with friend and foe alike. An aircraft not involved in the dogfight firing an AAM, or a ship firing a SAM into a dogfight, has an equal chance of locking onto any aircraft involved in the fight, friend or foe. Roll to determine which aircraft, friendly or enemy, is attacked by the incoming missile. The missile's chances to hit or miss its target are as normal. For simplicity's sake, treat there as being no weapon danger zone or secondary attack against another aircraft during a dogfight. Because they are all maneuvering, they all present the same radar cross section (RCS) to attacking missiles.

6.3.3.3.1 Gaining an Attack Position in a Dogfight. The dogfight, or "furball" or "bogey cloud," consists of a group of 2 or more aircraft wheeling within a small volume of air. The aircraft try to maneuver into a firing position on the enemy while keeping no enemy on their own tail. The chances of getting into a firing position depend on your aircraft's maneuverability and your opponent's.

Aircraft involved in a dogfight must first roll to see if they can gain position, or have a firing opportunity, meaning their weapons are aimed at the targeted aircraft. If they have gained such a position, they can then attack.

Rolls to gain an attack position in a dogfight are made on every 30-second engagement turn, for attack rolls made during the turn's second fire phase. While aircraft are certainly able to fire at a target every 15 seconds, it takes twice that long (on average) to "generate" a firing opportunity when 2 aircraft are maneuvering at the same time.

A missile or gun shot from an aircraft that is not in an attack position automatically misses its target.

Aircraft competing to gain a firing position use the "attack position formula." Calculate the chances of gaining an attack position, then roll 1D100.

Attack position formulas:

For a narrow-angle shot: (2 + att − def) x 10% Use this formula for attack positions involving forward-firing aircraft guns and narrow-angle tail missiles (marked "N" in Annex H).

For a wide-angle shot: (4 + att − def) x 10% Use this formula for attack positions involving flexible defensive guns and wide-angle tail missiles (marked "W" in Annex H).

For an all-aspect shot: (6 + att − def) x 10% Use this formula for attack positions involving all-aspect missiles (marked "A" in Annex H).

For a helmet-mounted-sight shot: (8 + att − def) x 10% Use this formula for attack positions involving all-aspect missiles with a slewable seeker used with a helmet-mounted sight capable of designating a target.

Example: a fighter with an ATA value of 3 engages a bomber with an ATA value of 0.5 in a dogfight. The fighter's chances of gaining an attack position for a gun shot are (2+3−0.5) x 10% = 45%. His chances of gaining position for a wide-angle-tail missile shot are 20 points better, at 65%. If he is carrying an all-aspect missile, such as the AIM9-L or the AA-11, his chances are 20 points better still, at 85%. With a helmet-mounted sight and a slewable-seeker IR missile, like the AA-11, the fighter can automatically gain a firing position since he then reaches 105%.

The player rolls 1D100 and gets a 62: he cannot fire his gun, but he can fire his wide-angle-tail missile if he chooses. He can also fire an all-aspect missile if he chooses. Remember that missiles not noted as usable in a dogfight have their ATA value halved during one.

6.3.3.3.2 Choosing an Opponent. During a dogfight, each aircraft must choose an opponent to maneuver against. While some choice is possible, targets nonetheless most often come down to chance. The side with more aircraft, however, has somewhat more freedom of choice.

Every aircraft involved in a dogfight should be represented by a counter.

Each player picks his dogfight opponents by randomly pairing aircraft with the enemy player. The enemy draws 2 aircraft at random from his group and places them on the playing surface. Then the "friendly" player draws 2 aircraft counters from his stack and places each one behind the enemy aircraft he wants to attack. Once all friendly aircraft have been assigned, the players switch roles and repeat the process.

Example: 2 F-18s and 2 F-14s are up against a group of 4 Su-24 Fencer attack aircraft and 4 MiG-29 Fulcrum interceptors. All aircraft are involved in the dogfight.

The US player would like to shoot down the attack aircraft, but cannot fully choose his targets because the MiGs have joined the dogfight.

The enemy player draws 2 aircraft: 1 MiG and 1 Fencer, and places them on the table. The friendly player draws 1 F-14 and 1 F-18. Thinking quickly, the friendly player realizes an F-18 has a better chance of gaining an attack position against a Fulcrum and assigns the F-18 to it, while the F-14 takes on the less maneuverable Fencer.

On the next draw, the enemy player draws 2 Fulcrums. The friendly player assigns his remaining F-14 and F-18 to each aircraft. He must pit the 2 aircraft he drew against the 2 aircraft drawn by the enemy player, and can only hope he can survive the fight so he can attack the Fencers next turn.

The US player has now selected his units and must roll to gain attack positions. Every successful roll must be noted, to determine who fires first.

The Russian player repeats the process, with the difference that after pairing his first 2 pairs with the US interceptors, he will still have 4 left. He can choose which US aircraft his remaining aircraft attack.

All aircraft planning to enter or remain in the dogfight must roll to gain position and are simultaneously subject to attack, if the enemy has enough aircraft for it.

The Fencers, on a bombing mission, may try to break off and flee while their Fulcrum escort engages the US interceptors. This splits the Russians into 2 groups, and the US player will have to decide whether to continue dogfighting the interceptors or pursue the attack aircraft. If the US player continues the fight, the Fencers will escape the dogfight.

The player with the highest position roll attacks first, followed by the 2nd-highest position roll, and so on. Since the roll to gain an attack position is based on the aircraft's and its weapons' maneuverability, this simulates the fact that the better aircraft in this respect will be able to get into position, then attack, faster. Of course, if a highly maneuverable aircraft rolls poorly, or misses its attack, its less well-equipped opponent will then be in position to score.

Example: 2 F-14 Tomcats (ATA 4.0) engage 2 MiG-23 Flogger Ks (ATA 3.0). All aircraft are lightly loaded, and both sides are equipped with all-aspect missiles.

For the F-14s: Gun shot: (2 + 4 − 3) x 10% = 30% chance of gaining a gun-shot position. Missile shot: (6 + 4 − 3) x 10% = 70% chance of gaining a position for launching a Sparrow or a Sidewinder.

For the MiG-23s: Gun shot: (2 + 3 − 4) x 10% = 10% chance of gaining a gun-shot position. Missile shot: (6 + 3 − 4) x 10% = 50% chance of gaining a position for launching an AA-10 or an AA-11.

Rolls for both sides: F-14#1 rolls 02 and can fire both gun and missile F-14#2 rolls 52 and can fire missile but not gun MiG-23#1 rolls 23 and can fire missile but not gun MiG-23#2 rolls 54 — too high a score to fire either missile or gun

The combatants will open fire in ascending order of their rolls: F-14#2 with 52, then MiG-23#1 with 23, and finally F-14#1 with 02. F-14#2 attacks MiG-23#2 first, and fires an AIM-9L that hits and downs the aircraft. Then MiG-23#1 attacks F-14#1. Firing an AA-11, it hits and downs F-14#1. F-14#1 never got the chance to fire.

The surviving F-14 and MiG-23 will continue the duel next turn.

It is possible for an aircraft to fire and be fired upon during the same engagement turn. An aircraft can only suffer 2 simultaneous dogfight attacks. If another aircraft gains an attack position, only the 2 highest rolls (the first to gain attack positions) will be allowed to attack.

6.3.3.3.3 Ending a Dogfight. A dogfight ends when all of a player's aircraft are destroyed, when both sides agree to break off, or when the faster aircraft decide to flee. In the latter case, the slower aircraft will get as many parting shots as their speed and range allow.

Aircraft leaving a dogfight, on their own or by mutual agreement, are subsonic (subtract 1D6 x 50 knots from the aircraft's speed at the start of the dogfight; the result cannot, however, be lower than the aircraft's stall speed). They will be at (1D6/3) − 1 altitude level lower than the level at which the dogfight started. The result cannot, however, be lower than the low altitude level. Each individual aircraft is placed 1D6+4 nm from the center of the dogfight, on a heading of 1D6-1 x 60 degrees.

6.3.3.3.4 Initial Position Advantage (optional rule). In Harpoon 4, an aircraft's starting position within the 10 nm dogfight circle is undefined. Aircraft movement, specifically that resulting from violent maneuvering, is too complicated to track at this level of the game. Instead, the aircraft is simply somewhere within the defined zone.

However, on the first turn of the dogfight, the starting position of the engaged aircraft is known. And a starting position can allow a dogfight to be ended quickly. On the first turn of a declared dogfight, if an aircraft begins the fight behind an enemy aircraft's 90° line (in the rear hemisphere), and there is no aircraft behind its own 90° line, add 10% to its chances of gaining an attack position. It is "advantaged."

If an aircraft begins the fight with an enemy behind its 90° line, and there is no enemy aircraft ahead of its own 90° line, subtract 10% from its chances of gaining an attack position. It is "disadvantaged."

In the example on page 6-10, A-7#1 is disadvantaged, since there are aircraft behind its 90° line. A-7#2 is advantaged, since it is behind the pair of MiG-19s. The MiGs are neither advantaged nor disadvantaged, since they have aircraft both ahead of and behind them.

6.3.3.3.5 Initial Speed Advantage (optional rule). If one aircraft is faster than the other by 50% of the slower aircraft's speed, increase the faster aircraft's defensive ATA value by 1.0. A faster aircraft has more energy and more options available.

6.3.4 Air Attacks Against Ships (Strike Warfare). Aircraft can attack ships, and sometimes submarines, with bombs, unguided rockets, guided missiles, and guns. Ordnance may be delivered on either the first or the second movement phase of an engagement turn.

If an aircraft is involved in a dogfight or trying to evade land-based anti-aircraft defenses (situations defined by its using the maximum allowed maneuver value, which depends on its load, when determining its chances of being hit), then the aircraft cannot carry out an attack that phase, and the pilot must be glad just to try to stay alive.

6.3.4.1 Unguided Weapons. The accuracy of attacks with unguided weapons will be affected by the quality of the bombing computer, the target's size, the target's maneuvers, and the altitude at which the ordnance is delivered. Modern bombing systems, which use high-speed digital computers and terrain-following radars, have significantly increased the hit chances of unguided bombs delivered at low altitude. In H4, there are four different types of bomb-delivery control systems:

• Manual: these are optically-based systems that use a gunsight or a bombing reticle to help the pilot/bombardier deliver his ordnance. Since adjustments between the weapon and the sight are made manually, this system is not very accurate and is only reliable at low altitude.

• Ballistic: these systems use an analog computer to calculate the bomb's impact point. Weapon release is still done manually.

• Computer-assisted: these systems use digital computers to more accurately calculate the impact point. The computer constantly shows the pilot where the bomb will land on his head-up display (HUD). This Continuous Computed Impact Point (CCIP) helps the pilot stay focused on the target, while the computer automatically releases the ordnance at the appropriate moment.

• Advanced: these digital systems belong to the 2nd generation. They use high-resolution terrain-following radars, laser rangefinders, imaging infrared detection systems, and GPS to further increase bombing accuracy. They can raise near-guided ordnance to a higher performance level when bombs are dropped at low altitude.

Bombs can be delivered against their target using three attack profiles: dive bombing, level (horizontal) bombing, and toss bombing. Each technique has its advantages and drawbacks. Very-high-altitude bombing with conventional unguided weapons is forbidden, since the chances of hitting the target are extremely low (far, far below 1%).

During an attack, an aircraft may drop all or part of its ordnance during the planned fire phase or the reaction fire phase. For example, if an aircraft has 4 hardpoints with 3 bombs on each, it can drop 12 bombs at once, or in several groups of 3, or it can drop them one at a time. A group of bombs dropped by an aircraft at the same moment is called a stick.

For dive bombing, the maximum number of bombs in a stick is 6, and larger bomb loads must be resolved in groups of 6 bombs. For level bombing, all the bombs are generally dropped in a single pass. Likewise, several single-bomb-per-aircraft attacks can be grouped into a single die roll, which significantly reduces the number of rolls while preserving statistical consistency.

Naval units are treated as point targets, and there are limits to the maximum number of aircraft that can attack one during a tactical turn without crossing each other's paths. To reduce the odds of a mmidair collision, only one group of aircraft can attack a ship during the same movement phase of an engagement turn.

Ships are also mobile, and can reduce bombing accuracy with sharp maneuvers. If the ship is moving at 25 knots or more and declares an evasive maneuver, multiply individual unguided-weapon hit chances by 0.75 for attacks at very low (V Low) or low altitude, or by 0.50 for attacks at medium or high altitude. This applies not only to unguided bombs, but to rockets, submunitions, strafing, and all forms of unguided attack.

6.3.4.1.1 Dive Bombing. This is the most accurate of the three bombing profiles, but it is also the most dangerous, since the aircraft cannot maneuver freely to avoid being hit by missiles or shells. For this reason, during the engagement turn in which the aircraft carries out a dive-bombing attack, it has an air-to-air value of 0.5. To carry out a dive-bombing attack, the aircraft must have a maneuver value of at least 1.0 with its current load.

Aircraft can carry out a dive-bombing attack from low, medium, or high altitude. For obvious reasons, dive bombing from very low (V Low) altitude is forbidden (well, not exactly forbidden, but the last operations officer to brief a very-low-altitude dive-bombing run was found hanging from the top of the main yardarm). They must also be within 5 nm or less of the target.

Once these conditions are met, the aircraft dives straight down onto the target. Due to the demands of the flight path, it will pass directly over the target. The player must control the aircraft's descent so that it passes over the target at the desired release altitude. The bombs will be released during the movement phase, as the aircraft passes over the target. They will reach their target during the same movement phase in which they were released. The attack will be resolved immediately. The aircraft will end the movement phase at one altitude level lower than the one at which it began.

To determine how many bombs hit their target, the player must consult the "dive bombing" section of the aircraft bombing tables and find the table for the altitude at which the ordnance was released. It is important to use the table for the altitude level at which the bomb was released, not the altitude level from which the aircraft dove. On the appropriate table, cross-reference the bomb's control system with the target's size to get a single bomb's hit percentage. If the value is an "x" followed by a number, this is the minimum number of bombs required for a 1% chance that a single bomb hits the target.

Example: an Argentine A-4C carries out a low-altitude dive-bombing attack against a Royal Navy Type 42 DDG. The A-4C has a ballistic control system and is armed with 4 Mk82 500lb bombs. The Type 42 DDG is a medium-size target and is steaming at 10 knots due to maneuvering restrictions in the Falklands Strait. On the low-altitude dive bombing table, the intersection of ballistic bomb control and medium target size gives a probability of 0.36 for each bomb.

Next, consult the "stick hit table." On the left, in the "single bomb Ph" column, find the single bomb's hit chances (as determined by the dive bombing table). If the single bomb's hit chances don't exactly match the listed numbers, use the nearest lower value.

Follow the top row and find the stick size, i.e. the number of bombs dropped in a single attack. Cross-reference these columns with the single bomb's hit chances. This will give you the chances that exactly one bomb hits the target, that 2 bombs hit the target, and so on, up to the maximum number of bombs dropped. If more than 6 bombs are dropped in one attack, resolve it by splitting it into groups of 6 bombs, adding, if needed, a stick made up of the remainder.

For example, an aircraft dropping 14 Mk82 500lb bombs should resolve the attack as 2 groups of 6 and 1 group of 2 bombs.

Roll 1D100. Compare the result to that attack's probabilities. If the roll is less than or equal to the given percentage, that number of bombs hit the target. If the roll is strictly greater than the Ph value in the "1 bomb" column, all the bombs missed their target. Any ordnance that misses a naval target is ignored.

Example: the A-4C attacking the British Type 42 carries 4 Mk82 500lb bombs. The single-bomb chance is 36%. This is rounded down to the nearest value in the "single bomb Ph" column, which is 35%. At the intersection of 35% single-bomb chance and a 4-bomb stick, we get:

Probability that 1 bomb hits: 82% Probability that 2 bombs hit: 44% Probability that 3 bombs hit: 13% Probability that 4 bombs hit: 2%

The player rolls 1D100 and gets 38. This is less than 44%, so 2 bombs hit their target, but the roll is not good enough for 3 bombs to hit.

6.3.4.1.2 Level Bombing. This attack profile is not as accurate as dive bombing, but it can be selected for any aircraft type regardless of its maneuver value. It also allows attacks at very low (V Low) altitude, with some risk. As with dive bombing, the aircraft is treated as having a value of 0.5 during the engagement turn in which it attacks. If it undertakes evasive maneuvers to raise this value above 0.5 during the previous movement phase of the engagement turn, its chances of hitting the target are halved, unless it has computer assistance or an advanced bombing aid system.

Aircraft can carry out this type of attack from very low (V Low) up to high altitude. However, if an aircraft releases low-drag bombs at very low (V Low) altitude, there is a 50% chance the bombs will not explode. If the bomb does explode on hitting the water, there is a 25% chance it will damage the attacking aircraft. Treat the damage as if a gun with an ATA of 3.0 had hit the aircraft.

The aircraft must be at one of the prescribed altitude levels and within 5 nm of the target if flying from very low up to medium altitude, and within 10 nm for high-altitude attacks. It must then fly directly at the target.

For high-altitude attacks, the bombs are released 6 nm from the target, after which the aircraft may maneuver freely. For medium-altitude attacks, the bombs are released 3 nm from the target. For low- and very-low-altitude attacks, the aircraft must fly directly over the target, and the bombs are released during the movement phase in which the aircraft reaches the target.

Bombs released from high altitude reach their target 2 phases after being dropped. Attacks from medium altitude hit one phase later, and those from low or very low altitude in the same phase.

To track time to impact and the location of falling bombs, place a counter next to the target showing the number of bombs, and another on top of it showing the time to impact.

The attack is resolved during the movement phase in which the bomb hits the ground. Resolve level-bombing attacks using the same procedure as dive bombing.

Aircraft releasing many bombs in a level-bombing attack must space their release to avoid interference between the ordnance. This spacing stretches the weapons out into a long stick. While a stick whose range error margin is partially corrected has increased chances of hitting the target, the spacing also reduces the chances of scoring more than one hit. When more than 6 unguided bombs are released in a single level-bombing attack, use the following procedure: determine the single-bomb hit chance from the aircraft bombing tables. Divide the number of weapons dropped by 6, rounding to the nearest whole number. Add this number to the table's hit chance and roll against this result for a 6-bomb stick. Refer to the table for the result.

Example 1: a B-1B drops 84 Mk82 500lb Snakeye bombs on a medium-size target from very low altitude (just to make a statement!). Advanced computer-assisted bombing against a medium-size target has a 24% chance to hit. 84 (bombs) divided by 6 gives 14. 25% plus 14 = 38%. This percentage, for a 6-bomb stick, on the "stick hit table" gives the following hit chances: 1 bomb: 90%; 2 bombs: 68%; 3 bombs: 35%; 4 bombs: 12%; 5 bombs: 2%; 6 bombs: no chance.

Example 2: an RAF Vulcan drops 21 1,000lb low-drag bombs, from medium altitude, on the Port Stanley airfield, to damage the runways. Since the Vulcan is trying to maximize its chance of hitting the target, it attacks along the runway's axis, treating it as a 150-foot-long target (medium size) from the aircraft's point of view. A ballistic sighting system, at medium altitude, attacking a medium-size target, has a 3% chance to hit. 21 bombs divided by 6 gives 3.5, rounded to 4. 3% plus 4 = 7%. This percentage, on the "stick hit table," gives the following hit chances:

• 1 bomb hits: 35%
• 2 bombs hit: 6%
• 3 bombs hit: 1%

No chance of 4, 5, or 6 bombs hitting.

Example 3: while a dive-bombing attack against a Type 42 DDG has good chances of hitting its target, the probability that a heavily-loaded A-4C gets shot down by a Sea Dart SAM fired from the Type 42 is very high. To increase the aircraft's survival chances, the A-4C carries out a very-low-altitude level-bombing attack against the Type 42 DDG. On the level bombing table, a very-low-altitude attack with a ballistic bombing system against a medium-size target gives a single-bomb hit probability of 5%. The Type 42 cannot carry out an evasive maneuver, and the A-4C does not evade during its approach.

At 5% for a 6-bomb stick, the hit chances are:

• 1 bomb hits: 19%
• 2 bombs hit: 1%

No chance of 3 to 6 bombs hitting.

6.3.4.1.3 High-Drag/Retarded Bombs. These are unguided bombs fitted with air brakes, parachutes, or ballutes (balloon-parachutes) to ensure as vertical a fall as possible once dropped. This lets an aircraft carry out a very-low-altitude level bombing run without suffering the penalties for bombs not exploding or damaging the attacking aircraft. Furthermore, since the aircraft is very close to the target at the moment of release, the attack's accuracy is better than with a low-drag bomb. Retarded bombs can also be used at low or very low altitude.

Aircraft Bombing Tables

Note: if a table entry shows "x#", this is the number of bombs needed for a 1% chance that a single bomb hits the target.

Level Bombing — Low-Drag Bombs

V Low Altitude

Bombing System	Large	Medium	Small	V Small
Manual	.08	.04	.02	x5
Ballistic	.11	.05	.02	x2
Computing	.15	.07	.03	.01
Advanced	.22	.12	.05	.02

Low Altitude

Bombing System	Large	Medium	Small	V Small
Manual	.11	.05	.02	x7
Ballistic	.14	.06	.02	x5
Computing	.20	.09	.03	x2
Advanced	.29	.14	.06	.01

Medium Altitude

Bombing System	Large	Medium	Small	V Small
Manual	.07	.02	.01	x13
Ballistic	.09	.03	.01	x9
Computing	.14	.05	.02	x5
Advanced	.21	.09	.04	x2

High Altitude

Bombing System	Large	Medium	Small	V Small
Manual	.02	.01	x5	x40
Ballistic	.03	.01	x3	x25
Computing	.04	.02	x2	x20
Advanced	.08	.03	.01	x12

Level Bombing — High-Drag (Retarded) Bombs

V Low Altitude

Bombing System	Large	Medium	Small	V Small
Manual	.27	.14	.06	.01
Ballistic	.30	.16	.07	.01
Computing	.37	.20	.09	.02
Advanced	.44	.24	.11	.03

Low Altitude

Bombing System	Large	Medium	Small	V Small
Manual	.24	.12	.05	x2
Ballistic	.27	.14	.06	.01
Computing	.30	.15	.07	.01
Advanced	.32	.17	.08	.02

Dive Bombing — Low-Drag Bombs

Low Altitude

Bombing System	Large	Medium	Small	V Small
Manual	.54	.29	.13	.02
Ballistic	.62	.36	.17	.03
Computing	.72	.46	.23	.05
Advanced	.82	.59	.33	.10

Medium Altitude

Bombing System	Large	Medium	Small	V Small
Manual	.33	.15	.06	.01
Ballistic	.41	.20	.08	.01
Computing	.51	.27	.12	.02
Advanced	.65	.38	.18	.03

High Altitude

Bombing System	Large	Medium	Small	V Small
Manual	.11	.04	.01	x9
Ballistic	.15	.06	.02	x5
Computing	.21	.08	.03	x3
Advanced	.31	.14	.05	.01

Unguided Rocket Attack (V Low/Low Altitude)

% Rocket Range	Large	Medium	Small	V Small
50%	.85	.70	.50	.40
>50%	.75	.60	.40	.30

Cannon Attack (V Low/Low Altitude)

Cannon Type	Large	Medium	Small	V Small
Internal	.80	.70	.60	.50
Pod	.70	.60	.50	.40

Precision-Guided Munitions

Guidance Type	Lg-Sm	V Small
1st Gen Cmd/SARH	.40	.30
2nd Gen Cmd/SARH	.50	.40
3rd Gen Cmd/SARH	.70	.60
1st Gen Laser	.60	.50
2nd Gen Laser	.70	.60
3rd Gen Laser	.80	.70
1st Gen EO/IR	.75	.65
2nd Gen EO/IR	.85	.75

Stick Hit Table (chance that exactly N bombs of a stick hit the target, by single-bomb Ph and stick size)

Single Bomb Ph	Stick=1 (1)	Stick=2 (1)	Stick=2 (2)	Stick=3 (1)	Stick=3 (2)	Stick=3 (3)	Stick=4 (1)	Stick=4 (2)	Stick=4 (3)	Stick=4 (4)
.85	.85	.90	.72	.90	.90	.61	.90	.90	.89	.52
.80	.80	.90	.64	.90	.90	.51	.90	.90	.82	.41
.75	.75	.90	.56	.90	.84	.42	.90	.90	.74	.32
.70	.70	.90	.49	.90	.78	.34	.90	.90	.65	.24
.65	.65	.88	.42	.90	.72	.27	.90	.87	.56	.18
.60	.60	.84	.36	.90	.65	.22	.90	.82	.48	.13
.55	.55	.80	.30	.90	.57	.17	.90	.76	.39	.09
.50	.50	.75	.25	.88	.50	.13	.90	.69	.31	.06
.45	.45	.70	.20	.83	.43	.09	.90	.61	.24	.04
.40	.40	.64	.16	.78	.35	.06	.87	.52	.18	.03
.35	.35	.58	.12	.73	.28

(Stick sizes 5 and 6 follow the same declining pattern; use the nearest lower Ph row and interpolate proportionally if the printed table does not extend far enough.)

Level-bombing attacks with retarded bombs are resolved the same way as with low-drag bombs, except that the retarded-bomb table is used to find the single-bomb hit probability instead of the low-drag bomb table.

Example: replace the Argentine air force's A-4C with a Navy A-4Q, which can drop Mk82 Snakeye retarded bombs. The attack on the Type 42 DDG is identical with the A-4Q: a level pass with 4 bombs. On the level bombing — retarded bombs table, a very-low-altitude attack by a ballistic bombing system against a medium-size target gives a single-bomb hit probability of 16%. For a 4-bomb stick, the hit probabilities are:

1 bomb: 50%; 2 bombs: 12%; 3 bombs: 1%. No chance of 4 bombs hitting.

6.3.4.1.4 Toss (Lob) Bombing. This last release profile is the least accurate, but it offers the best protection for an aircraft that is not within range of light AAA or portable SAMs. To carry out a toss attack, an aircraft must have an ATA value of at least 1.0 and have a computer-assisted or advanced bombing system.

To carry out a toss-bombing attack, the aircraft approaches the target at very low, low, or medium altitude and, at 5 nm from it, pulls up sharply, literally lobbing the bomb at the target. The minimum range for this attack profile is 1 nm. The bombing computer automatically releases the bomb at a precise point in the climb, giving it a ballistic trajectory to a target located between 1 and 5 nm away. The aircraft finishes its movement pulling away from the target in the opposite direction, at medium altitude.

Only one air-to-ground weapon can be tossed per attack. Self-propelled unguided ordnance (rockets) cannot be tossed. High-altitude toss attacks are reserved for nuclear weapons.

To resolve a toss-bombing attack with unguided weapons, consult the appropriate low- or medium-altitude dive bombing table. Once you have the single-bomb hit probability, multiply it by 0.15 to get the final hit percentage for a toss attack. Laser-guided and EO/IR bombs can be tossed without degrading their hit probability. However, the aircraft tossing the bomb cannot be the same one designating the target with a laser or maintaining the digital link (EO/IR).

6.3.4.1.5 Cluster Bombs. Cluster bombs are a special type of unguided bomb distinguished by the weapon's area of effect. The probability of damaging a target is higher with cluster bombs, which scatter their bomblets over a wide area, than with a standard bomb of equivalent weight. Cluster bombs cannot be dropped from very low altitude, because the submunitions would not have time to be ejected from the dispenser. A cluster bomb dropped from very low altitude automatically fails and causes no damage.

Cluster bombs have 2 dispersal modes, based on the size of the area covered, which the pilot can set while the aircraft is in flight. "Large" mode covers an area twice as big as "small" mode.

To use cluster bombs, the aircraft may choose whatever attack profile it wants, but the attack will always be resolved on the dive bombing table.

For level or dive attack profiles, if the pilot selects "large" mode, use the low-altitude section of the dive bombing table, regardless of release altitude. Use the medium-altitude section of the dive bombing table if "small" mode is selected. For a toss attack, use the high-altitude section for both small and large modes. For a toss attack with cluster bombs, the single-bomb hit probability is not multiplied by 0.15.

The damage a cluster bomb inflicts on a target depends on the target's size and the dispersal mode selected. Larger targets are usually hit by more submunitions, and so suffer greater damage. A large dispersal mode will increase the hit chances, but will cause less damage than small mode. To determine how many bomblets damage a target, roll 1D6 on the submunition damage table, referring to the target's size and the dispersal mode selected.

If the land target is a group of small targets, such as vehicles or aircraft, roll to see how many are attacked by the cluster bomb. In large mode, 1D6 targets will be attacked by the bomblets. In small mode, 1D6/2 (rounded up) targets will be attacked. Damage to each target is rolled individually.

Submunition Damage Table

Target Size	Large Mode (% damage pts)	Small Mode (% damage pts)
Large	20 + (1D6 x 10)	40 + (1D6 x 10)
Medium	10 + (1D6 x 10)	30 + (1D6 x 10)
Small	1D6 x 10	20 + (1D6 x 10)
V Small	1D6 x 5	10 + (1D6 x 10)

Example: a French Air Force Mirage 2000 drops 2 Belouga cluster bombs on an Iraqi Osa II PTG. The pilot selects large mode to maximize the chance of hitting the patrol boat. The Osa II is a small target, and the Mirage 2000 has a computer-assisted bombing system. Because large mode was selected, use the low-altitude section of the dive bombing table, which, for a computer-assisted bombing system against a small target, gives 23% for a single bomb. The Osa II does not realize the French aircraft is attacking it, so it is not considered to be taking evasive action, and the hit probability stays at 23%. On the Stick Hit Table, for a 2-bomb stick, we get: 41% that 1 bomb hits, 05% that 2 bombs hit. Rolling 1D100, the French player gets 21, indicating 1 bomb hits the target. The French player then rolls 1D6 for damage. He gets a 4 against a small target, meaning 40% of the bomb's damage is inflicted on the Osa II. A Belouga cluster bomb inflicts 36 damage points, meaning 14 damage points are inflicted on the Osa II (14.4 rounded to the nearest whole number). Since the Osa II can only absorb 9 damage points, it goes down like spaghetti in a pot.

6.3.4.1.6 Unguided Rockets. Unguided rockets are, in some ways, similar to cluster bombs in that they involve a large number of explosive projectiles spread over a target area. To carry out a rocket attack, the aircraft must be at low or very low altitude. At very low altitude, the aircraft must use the level-bombing attack profile (actually a shallow dive), while attacks from low altitude require the aircraft to use the dive-bombing profile. Unguided rockets cannot be used in toss attacks. Since unguided rockets are generally carried in pods, each pod is treated as carrying out the attack, rather than each rocket individually. Each pod can attack once, firing all its rockets during the attack.

To determine hit chances for a rocket attack, consult the unguided rocket attack section, taking into account the target's size and range. Note that for range, the question is whether the rockets are fired at a distance equal to or less than half their range or not. To resolve a rocket attack, the player may roll 1D100 for each firing rocket pod, or take the table's hit probability and use the appropriate column of the Stick Hit Table.

Damage inflicted by a rocket attack is calculated the same way as for a wide-area cluster bomb.

6.3.4.2 Guided Weapons. These weapons include both missiles and "smart" bombs, or precision-guided munitions (PGMs). Generally, missiles are propelled by a rocket or a turbojet, while PGMs are generally glide or free-fall bombs. The values for each of these types are given in Annex G4, guided air ordnance.

Each guidance type is covered in section 5.3. A missile's guidance system, range, and speed are given in Annex G4. Missiles fly on either a cruise or a ballistic profile. Cruise-profile missiles will climb or descend, after launch, to their cruise altitude and stay there until reaching their target. They may execute a final maneuver, either a popup or a very steep dive, depending on their design. Ballistic-profile missiles will fly straight to their target and will not maneuver. Ballistic-profile missiles will only fly their full range if launched from high or medium altitude. If released from low altitude, their range is halved. Guided missiles cannot be launched from very low altitude or nap of earth.

Most PGMs are not self-propelled and follow a curved ballistic path to the target. Their range also depends on their release altitude. For non-self-propelled weapons, the range given in Annex G4 is a maximum range when released from high altitude. If the weapon is released from medium altitude, the range is halved. Low-altitude attacks with non-self-propelled PGMs are exclusively limited to 3rd-generation laser-guided bombs. Their range is then quartered.

Generally, an aircraft can launch one guided weapon per 15-second aircraft fire phase. The selected target must be within a ±30° arc of the aircraft's flight path. Some types of guided weapons have specific constraints that must be observed at launch.

6.3.4.2.1 Command-Guided and Semi-Active Radar Homing (SARH) Weapons. These are controlled by radio or radar from the launching aircraft. The aircraft must have a clear line of sight (LOS) to the target, from launch until the target is reached. If LOS cannot be maintained, the weapon's chance of hitting its target is quartered, since it naturally drifts off its intended course. Smoke, dust, fog, and clouds will not affect these weapons, but will affect visual LOS. To determine hit chances against a naval target, use the precision-guided munitions section of the aircraft bombing tables, taking into account the target's size class and the weapon's control system or SARH generation.

6.3.4.2.2 Semi-Active Laser Homing (SALH) Weapons. These weapons include laser-guided bombs (LGBs) and missiles. A laser designator "paints" the target, and the weapon homes on the reflected laser light. The designator may be carried by the launching aircraft or by another friendly unit with LOS to the target. This may be an air, land, or naval unit.

If the launching aircraft is carrying out a level or dive attack, it can designate the target with its own laser. If the aircraft is carrying out a toss attack, another unit must designate the target with a laser. This unit may be a surface platform or another aircraft. To use SALH weapons, the aircraft must have a laser rangefinder/designator as one of its detection systems, or carry a pod as part of its payload. A designator can "paint" the same target for any number of SALH weapons. However, only 2 weapons can attack the same target per engagement turn without affecting the hit probability. The 3rd weapon and beyond will attack a target obscured by smoke, dust, and debris thrown up by the previous explosions. This dust and debris is produced whether the first 2 weapons hit or miss their target.

Air attacks with SALH weapons must maintain clear line of sight to the target from launch until the weapon reaches its target. This requires the aircraft to keep the target within a 270° forward arc (135° on each side of the nose, with a 90° blind spot centered aft). If the aircraft exceeds this limit, or if clouds or smoke obstruct visibility, line of sight is lost, and the weapon's chance of hitting the target is quartered.

Russian attack aircraft, such as the MiG-27, Su-22, Su-24, and Su-25, all have laser designators built into their nose. This means they must keep the target within a ±45° arc of their flight path to maintain line of sight.

1st- and 2nd-generation SALH weapons must have line of sight to the designated target when launched or released. 3rd-generation SALH guidance systems, on the other hand, can lock onto a designated target after launch, as long as the weapon has not traveled more than half its maximum range. To determine hit chances against a naval target, consult the precision-guided munitions section of the aircraft bombing tables, taking into account the target's size class and the generation of the laser guidance system used.

If a target is obscured by smoke or dust, it will take 4 tactical turns to clear if wind speed is 15 knots or less. It will take 2 tactical turns if wind speed exceeds 15 knots. A new attack cannot be carried out without penalty until the air has cleared.

6.3.4.2.3 Electro-Optical/Infrared Homing Weapons. These weapons use TV circuitry (ordinary or light-amplified) or imaging infrared detection systems to home in on the target. The weapon's operator has a TV display and, via a digital link, steers the bomb onto its target. Since the operator can make out small details, he can literally guide the weapon to a window or a door. It's no surprise these robotic kamikazes are the most accurate PGMs. However, the operator can only control one weapon at a time, so using several aircraft may be necessary to launch a salvo of EO/IR weapons. These weapons can be locked onto a target and fired at a rate of one per fire phase. They can be launched against several targets, or against a single one, as long as there is an aircraft to control each weapon in flight.

To attack with an EO/IR weapon, the firing aircraft must maintain clear line of sight to the target, from launch until the weapon reaches its target. However, since the digital radio link is not dependent on orientation, the aircraft is free to maneuver however it likes after launch. 2nd-generation weapons can be launched before the target is spotted, but this requires the aircraft to carry a digital-link pod. The target must be spotted while the weapon covers the first half of the distance to its target. The maximum range can then be used.

Clouds and smoke can hide the target from the weapon's detection system. As with laser-guided weapons, LOS is lost and the hit probabilities are quartered. See 6.3.4.2.2 for how long it takes for dust to clear. To determine hit chances against a naval target, consult the precision-guided munitions section of the aircraft bombing tables, taking into account the target's size class and the generation of the EO/IR guidance system used.

6.3.4.2.4 GPS-Guided Munitions. The Global Positioning System (GPS) has only recently been incorporated as a guidance system for blind gravity bombs. By combining the GPS navigation signal with a simple control system, a "blind" bomb becomes an effective, low-cost weapon. The US Joint Direct Attack Munitions (JDAM) are an example of a GPS-guided weapon.

To use GPS-guided bombs, the aircraft must have an advanced computer-assisted bombing system. The weapon cannot be released from very low or low altitude, because it would not have time to integrate the satellite navigation data before hitting the ground. All attacks carried out from very high or high altitude, level or dive, are resolved on the dive bombing table as if the weapon were released from low altitude. Attacks carried out from medium altitude are resolved on the dive bombing table as if the weapon were released from medium altitude.

GPS-guided bombs only benefit from an accuracy bonus when used against stationary targets. Against a moving target, treat GPS-guided bombs as standard "blind" bombs, unless the weapon has a terminal guidance system. If it has terminal guidance, resolve the attack on the appropriate PGM table.

6.3.4.3 Strafing. An aircraft armed with machine guns or cannon can use them to attack ships. Although such attacks will not necessarily sink a ship, they can kill personnel topside, and damage weapons and detection systems. Up to 4 aircraft maximum can simultaneously strafe a ship during the same engagement turn.

To strafe a ship, the aircraft must be at very low or low altitude and, during its movement phase, fly directly at the target. On the cannon attack table, take into account the gun type and the target's size to determine the hit chances.

Example: an F-4E makes a strafing run on an old Soviet P-6 PT boat with its single internal 20mm rotary Vulcan cannon. The P-6 is a small target and is maneuvering violently. The hit probability for an internal gun against a small target is 60%. Since the P-6 is taking evasive action, the hit probability is multiplied by 0.75 (see section 6.3.4.1) and is thus reduced to 45%.

If the target is hit, the gun's damage is inflicted on the ship. Roll normally on the appropriate critical-hit damage table for that target type. Check all critical hits against the following table to determine whether that critical hit can be caused by that gun/machine-gun caliber type.

Ship Strafing Table

Aircraft's Largest-Caliber Weapon	Permitted Critical Hits
Under 20mm	Aircraft, bridge/CIC
20-25mm	Aircraft, bridge/CIC, weapon, detection system, cargo
27-30mm	Any critical

If the critical hit rolled is not listed above, it is ignored. Machine guns under 20mm cannot penetrate armored targets. However, 20-25mm guns can penetrate light armor, and larger guns (e.g. 30mm) can penetrate medium armor. If the gun cannot penetrate the armor at that location, the critical hit is ignored.

Optional rule: if the strafed ship is a carrier, the attacking player may declare he is targeting aircraft parked on its flight deck (he cannot choose a specific aircraft; randomly determine by die roll which are attacked). Roll for the gun attack normally, treating the aircraft as a very small target. If the targeted aircraft is hit, it is destroyed (treat the shot as a critical hit against the aircraft, section 7.3.2.1). 1D6/3 aircraft on the flight deck (rounded up) may be attacked by the strafing aircraft.

6.3.4.4 Target Aspect (optional rule). Strafing and rocket attacks that sweep down the length of a ship (an attack along the ship's centerline, or within 20° of it) get a +10% to-hit modifier and a +20% damage modifier. This represents the extended target area when the attack runs along the ship's length.

6.3.4.5 Phaser Attack. Just to see if you were paying attention!

6.3.5 Air Attacks Against Land Targets. Air attacks against land targets are resolved the same way as those against ships. Compare the target's size class to the type of air attack carried out to find the hit probability on the aircraft bombing tables. Resolve the attack taking into account the appropriate modifiers for naval targets described earlier. The great majority of land targets do not move, and so do not take evasive action.

6.3.5.1 Damage to Land Targets. Attacks against ships are meant to breach their hull to sink them, or to destroy key equipment so they can no longer move or fight. On land, buildings will not sink, and they have few essential systems to lose. Instead, the damage inflicted on a target each tactical turn determines whether the target, a building or any other land target, suffers a critical hit or is destroyed.

Procedure: before an attack, each aircraft is assigned to attack a specific target. When the attack is carried out, the aircraft closes on the target and drops its ordnance on it. Hits against each target are totaled. Land-based targets, like ships, have damage-point values based on their size. A large building might be able to absorb up to 400 damage points. If it is hit 3 times: once for 50 points, once for 100 points, and a 3rd time for 75 points, the total damage inflicted on it is 225. After each tactical turn in which a land target takes damage, divide the damage inflicted by the damage points the structure could originally absorb. Roll 1D6 and refer to the damage percentage on the Land Target Damage Table.

A critical hit means the installation and the units within it cannot fire, use their detection systems, or move until repaired. A destroyed result means the installation and all units within it are destroyed and can no longer be repaired.

6.3.5.2 Missed Attack Against a Land Target. On land, other units may be based near the target of a failed attack.

If shells, bombs, or rockets miss the intended target, roll 2 x 1D6. The 1st die gives the direction the weapon takes on the deviation diagram, and the 2nd gives the size of the deviation on the miss-magnitude table. The deviation diagram is centered on the originally intended point, and the arrow is aligned with the aircraft's heading.

Miss Magnitude Table

1D6 Roll	Miss Magnitude
1-4	Miss distance x 1
5-6	Miss distance x 2

Miss Distance (yards)

Attack Type	Distance in Yards
Short-range gunfire	50
Medium-range gunfire	100
Long-range gunfire	200
Dive bombing	50
Bombing altitude (low/med)	200
Bombing altitude (High)	500
Unguided rockets	50
Strafing	50
Guided missiles/glide bombs	15

This procedure assumes all weapons are aimed at a single point/target. If instead the aircraft drops a stick of bombs, other targets may be attacked if they lie along its flight path.

If 30 or more bombs are dropped in a single pass, and a potential target is within 250 yards of the flight path and within one nm before or after the target, it is also attacked by the stick of bombs.

Use the level-bombing rules (6.3.4.1.2) but divide the number of bombs involved in the attack by 4. If a B-52 drops 84 bombs on a target, and another potential target lies along its flight path, each will receive the following attack: 84/4 = 21 bombs; 21/6 = 3.5 → 4. The single-bomb hit chance will be 24% + 4 = 28%. A single bomb will hit each additional target if the attack hits its target. All other bombs miss.

6.3.5.3 Airfield Attacks. Airfields are a special class of target, somewhere between a ship and a land target. Most land targets are single objects, like a building, a bridge, or a road junction. An airfield has several different components, each of which can be attacked separately. As with a ship, an attacker can inflict critical hits that affect operations from the airfield. Unlike a ship, it cannot be sunk. Its facilities are also spread over a larger area, letting the attacker select a specific section to target.

There are other types of land targets similar in composition to airfields: ports, rail yards, and military bases. The format described here can also be used for such targets.

Procedure: a map of the target area is used to plan the raid. Attacking aircraft may carry out one or more types of attack. The attacking player must determine which aircraft will fill which role corresponding to which part of the planned mission, and equip them appropriately.

6.3.5.3.1 Suppression of Defenses. An aircraft may try to suppress the target area's anti-aircraft defenses by attacking the guns, missiles, or their fire control. This can be played as a standard attack against a land target. The loss of AA defense weapons will affect the other aircraft's chances of surviving the raid.

6.3.5.3.2 Runways. The 2nd type of attack is more conventional: trying to put the runways out of action. Conventional gravity bombs or specialized anti-runway bombs may be used, but the chances of success will be lower with standard unguided bombs. Anti-runway bombs are specially designed to penetrate the runway surface and destroy its pavement over a larger section. Engineers cannot simply fill in a hole; the damaged sections must be completely removed and replaced. Delayed-fuze bombs and minelets (the submunition is a mine) can be mixed in to delay repairs.

Retarded bombs cannot be used against runways because their braking system prevents them from reaching the speed needed to penetrate the surface.

The attacking aircraft can carry out a dive or level attack against the runway at an angle of between 10 and 30° from its centerline. All ordnance is generally dropped in a single preprogrammed attack to maximize the chance that at least one bomb hits the target and creates a crater (the aircraft can drop its ordnance over several passes, but this significantly reduces its survival chances). Unguided bombs must be dropped in a dive attack, or from medium or high altitude in a level attack. Toss bombing may also be used, but it is the least accurate method of attack, even against a target as large as a runway.

Treat the runway as a medium-size target. Although it may be a mile or more long, an aircraft will only attack a small portion of its length. Resolve the attack using the appropriate rules section (unguided or guided bombs).

A crater is an obstruction that makes that section of runway unusable to an aircraft. A single crater probably won't be enough to make the runway unusable for every aircraft type. The more craters a runway has, the better.

Anti-runway bombs are described in Annex G5. Each attack may involve a single weapon like the Durandal, or a submunition weapon like the BAP100. Roll 1D100 for each strike. If the result is less than or equal to the crater chance, the runway has been seriously damaged.

The 3 factors affecting a runway are its original length, the number of craters on it, and the type of aircraft trying to use the runway. Players must keep track of the number of craters affecting each runway at the airfield. Use the table below to determine which aircraft type can use a damaged runway.

Runway Usability Table

Aircraft Classes:

• I = four-engine aircraft (heavy transports, patrol aircraft, heavy bombers)
• II = twin-engine aircraft without afterburner (light transports, older attack aircraft, medium STOL transports)
• III = jet combat interceptors
• IV = STOL aircraft, light civil or observation aircraft
• "—" = landing forbidden for all CTOL aircraft

Runways can be repaired quickly. Special techniques and materials have been developed that let minor damage be repaired in 2 to 4 hours, and more serious damage in 1 or 2 days.

If submunition weapons were used against the runway, work cannot begin until the area has been cleared of mines and delayed-fuze bombs. This takes 1D6 intermediate turns. Once the area is cleared, roll 1D100 for each crater on the runway every 4 hours. There is a cumulative 33% chance the crater is repaired for each consecutive 4-hour period. The number of craters that can be repaired simultaneously depends on the number of engineer teams available at the air base. Each team can only work on one crater at a time.

6.3.5.3.3 General Attacks. In this last attack type, the player sends his aircraft to attack the airfield's buildings and facilities. Because even with damaged runways, many other essential functions, such as aircraft repair, can continue.

The player rolls to attack unspecified targets. Misses are ignored. If he hits the target and scores a critical hit, the results are given by the general attacks table.

6.3.6 Attacks Against Submerged Submarines. An aircraft can attack a submerged target with torpedoes, or conventional or nuclear depth charges. Torpedoes must search for and acquire the target before they can attack it. Depth charges and depth bombs will attack the turn they are dropped. When the weapon reaches its target and attacks, determine all modifiers, then roll 1D100 to see if the target is hit.

6.3.6.1 Limitations. Aircraft can only attack a known submarine target with torpedoes and depth charges. They can use nuclear depth bombs to carry out area attacks or attack lost contacts.

General Attacks Table

Target Type	Damage Pts	Armor Level	Size Class	Critical Result
Aircraft in the open	5	None	Small	Destroyed or damaged
Sheltered aircraft	15	Light	Medium	Destroyed or damaged
Hangar	120	Light	Large	1-3 aircraft destroyed or damaged
Hardened Aircraft Shelter (HAS)	75	Heavy	Medium	Structure and aircraft destroyed
Radar	25	None	V Small	No landings if visibility < 1 nm, landing value /2
Control tower	50	Medium	Small	Takeoff and landing value /2
Maintenance	250	Light	Large	Aircraft/runway repair chances /2
Munitions depot	125	Heavy	Medium	1D10x10% chance one ordnance type destroyed (except unguided bombs)
Heavy tank	8	Medium	Small	Destroyed
Light tank	5	Light	Small	Destroyed
Armored personnel carrier	5	Light	Small	Destroyed
Truck/car	2	None	V Small	Destroyed
AAA gun	5	None	V Small	Destroyed
Fixed SAM	8	None	Small	Destroyed
Mobile SAM	5	None	Small	Destroyed

6.3.6.2 Parachuted Torpedoes. Parachuted torpedoes must be dropped from low or medium altitude, at no more than 50% of the aircraft's full-military-power speed. The aircraft must know the submarine's position, either from its own detection systems or from a friendly unit's report. One torpedo may be dropped per engagement turn. Helicopters can drop torpedoes while moving or hovering.

Once the torpedo is in the water, it will activate immediately, following the selected search mode's instructions (circular at constant depth, or helical). If the targeted submarine is within the acquisition cone, the torpedo will attack it. To resolve the attack, see section 6.5.2.2, homing torpedo attacks.

Remember that if several torpedoes are dropped against the same target, there is a risk of mutual interference (see section 5.5.3.2).

6.3.6.3 Conventional Air-Dropped Depth Charges. Air-dropped depth charges are still useful weapons in shallow water, where homing torpedoes suffer from high ambient noise and reverberation. To carry out an air-dropped depth-charge attack, the attacking aircraft must have visual or MAD contact from the previous detection phase. Over the next 2 aircraft movement phases, the aircraft must fly in a straight line to position itself over the submarine's location, then drop as many depth charges as it wants.

The chances of an air-dropped depth-charge attack succeeding depend on how many depth charges are dropped and whether they detonate at the correct depth. Since many airborne detection systems cannot provide accurate depth information, except for the LIDAR detection system, the ASW aircraft commander must make an educated guess about the submarine's depth. Since many air-delivered depth charges have a maximum "intermediate I" depth setting, this is not as hard as it sounds. A player has a 50% chance of guessing the depth level at which the charge should explode. And if the aircraft knows whether the submarine is above or below the layer, the guess becomes certain. Furthermore, if a depth charge has an acoustic guidance system, like the Russian S3V, depth information is not required. Resolve all air depth-charge attacks by referring to section 6.4.3.3, depth-charge attacks.

Example: a Russian Be-12 Mail maritime patrol aircraft has detected and localized, with its sonobuoys and MAD, an unidentified submarine, which it attacks with 8 PLAB 120 depth charges. Data from the deployed sonobuoys shows the submarine is moving slowly (< 5 knots) and is below the layer. The depth charges are set to detonate at intermediate I depth. Assuming the submarine is at intermediate I, the final probability that 8 charges hit the target is:

Base hit probability (Ph) = 8/100 = 0.08 Depth modifier: x 1 (target within 1 intermediate I zone) Max damage (Ph) = 0.08 Half damage (Ph) = 0.16

Had the Be-12 been fitted with acoustically-guided SV3 depth charges, the final probabilities of inflicting maximum damage would have been 40% (0.08 x 5 for acoustic guidance), and of inflicting half damage would have reached the maximum Ph of 80%.

6.3.6.4 Speed and Altitude Limitations. Because depth charges are designed to explode underwater, they must survive impact when they hit the surface. Since this becomes increasingly difficult as the aircraft's speed and altitude increase, limitations are placed on it so the depth charges function properly. Consequently, all conventional air-dropped depth charges must be delivered at a speed below 300 knots, and at no higher than low altitude. For each knot above 300 knots, there is a cumulative 2% chance the depth charge fails to detonate; for each altitude level above low altitude, there is a cumulative 50% chance it malfunctions.

Example: the Be-12 Mail carries out its attack, dropping the PLAB 120 depth charges from low altitude, but at a speed of 315 knots. The chances the depth charges malfunction due to excessive speed are 30% ([315 − 300] x 2%) for each one.

6.3.7 Pilot Experience (optional rule). An aircraft is an extension of the pilot's hands, and its performance reflects his skill. Air combat has repeatedly shown that individual pilot skill is a major factor in the outcome of a fight. In no other area of naval warfare do an individual's skill and experience affect the outcome of combat as much as in the air.

Although all operations aboard an aircraft are affected by pilot skill, 3 areas dominate: dogfighting maneuvers, attacks with unguided ordnance, and hedge-hopping (very-low-altitude flight). In these 3 areas, practice makes for feats of skill.

Pilot experience is graded into 4 levels:

• Rookie — The typical Japanese kamikaze pilot of late World War II. This individual has no business being in an air fight. There are still some today, and they are sometimes, unfortunately, drawn into combat. With 4 hours of flight time on a single aircraft type, he is just competent enough to fly an aircraft from point A to point B. He will suffer severe penalties due to his inexperience.

• Novice — Described as a "greenhorn" by the naval aviation community, this pilot has basic combat training but lacks experience. He has never felt the pressure or lived through the demands of actual combat conditions. He has never used the full capabilities of his aircraft and does not know its limits.

• Experienced — This pilot has flown several combat missions, or enough training missions, to have developed instinctive reactions that let him handle most situations. More importantly, he has gained "situational awareness," i.e. the ability to picture the rapid movements and possibilities of a three-dimensional fight.

• Veteran — This individual has many air-combat victories and several hundred combat sorties to his credit. He knows how to push his aircraft to the limits of its capability and even beyond, without endangering himself. He uses his knowledge and situational awareness to destroy the enemy as efficiently as possible. This individual is a survivor. Barring bad luck or overwhelming numbers, this pilot cannot be beaten.

The pilot experience modifier table lists the actions affected by pilot skill.

Pilot Experience Modifiers

Action	Rookie	Novice	Experienced	Veteran
Gaining an attack position in a dogfight	−20%	0%	+20%	+40%
Attack with unguided ordnance, including guns and level bombing	−10%	0%	+5%	+10%
% chance of crashing per tactical turn at very low altitude/nap of earth (hedge-hopping)	+3%	+2%	+0%	−2%
Landing crash chances	+2%	0%	−2%	−5%
Number of permitted air-to-air gun attacks (ammunition)	3	4	5	6

6.4 Surface Ship Attacks

Surface ships are the naval platforms that carry the widest variety of detection systems and weapons. Ships can engage aircraft or other surface ships with guns, missiles, or torpedoes, and attack submarines with torpedoes, standoff missiles, depth charges, or ASW mortars. They often carry aircraft fitted with their own detection systems and weapons, which lets them extend the spatial reach of their capabilities. Surface ships also have the unique ability to attack different types of platforms simultaneously. Any ship can attack air, surface, or submarine targets (with different weapons) at the same time.

6.4.1 Anti-Air Warfare (AAW). Surface ships can defend themselves against air attacks with guns, missiles, or energy weapons. After finding the final modified hit probability, the player rolls, and if the air unit is hit, it is immediately removed from the game. A hit against an aircraft is considered enough to destroy it outright or damage it enough that it aborts its mission. A hit against a missile destroys it.

6.4.1.1 Anti-Aircraft Guns. Anti-aircraft guns use the same combat resolution system whether shipboard or land-based. Annexes C2 and C3 contain all the necessary information about artillery with any anti-aircraft capability. The 2 tables are similar, Annex C2 covering naval artillery and Annex C3 land-based artillery.

The annexes give the maximum range, maximum altitude, possible fire-control modes, and remarks for each anti-aircraft defense system. There are also 2 hit-chance values, one for targets between 0 and 50% of maximum range and the other for targets between 51 and 100% of that same range. Accuracy drops significantly in the outer part of the range band. The fire-control modes column gives the various systems available for aiming the gun at the aircraft. Each system has its advantages and drawbacks. The 3 fire directors are radar, electro-optical, and optical.

Radar control (RA) — The gun receives information from a dedicated radar system used to calculate a firing solution to correctly aim the gun. Unfortunately, the radar can be jammed or decoyed away from the target with chaff. When this happens, the gun system's effectiveness is reduced. Advanced radar systems are also easily confused by targets close to the water. Unless the remarks column states that the fire-control radar has sea-skimmer acquisition capability, the gun will have a reduced chance of hitting a very-low-altitude target.

Electro-optical (EO) — This entry indicates the fire director consists of light-amplifying cameras, conventional TV cameras, or IR detection systems, and generally uses a laser rangefinder to gather all the data needed to aim the gun correctly. If used together with a radar system, the EO system will not improve the gun's overall accuracy, but will give the weapon system a high degree of ECM resistance. If used alone, EO fire directors can allow a precision attack with little or no warning for the target. This can be especially useful in low visibility or at night. If an attacking aircraft is "surprised" by an anti-aircraft gun, receiving no signal warning it of the fire directed at it, it is treated as a non-maneuvering target.

All electro-optical systems have sea-skimmer acquisition capability.

Optical (OP) — A gun system using optical mode is said to be in "local control." This is often the default/backup mode for radar- or EO-directed artillery. Being in optical mode means a significant reduction in hit chances. For guns for which the optical system or local control is the only fire-control (FC) mode, there is no penalty. This must be accounted for when calculating hit chances. Optical systems all have sea-skimmer acquisition capability.

AA gun hit-probability modifiers:

• Non-maneuvering aircraft (including those surprised by gunfire), or surface-to-surface missiles above very low altitude and slower than 1,000 knots: double the hit chances.
• Target moving faster than 8.3 nm/engagement turn (1,000 knots): reduce hit chances by 10%.
• Crossing target (90° per engagement turn): halve hit chances.
• Anti-ship missile carrying out terminal maneuvers, including popup: reduce hit chances by 15%.
• Sea-skimming (very low altitude) target, halve hit chances, unless the gun system has sea-skimmer acquisition capability.
• Guns in local control (OP mode): halve hit chances. This modifier does not apply to guns whose only fire-control (FC) mode is OP.
• Against a hovering helicopter: double (x2) hit chances. Do not apply the very-low-altitude modifier to hovering helicopters.
• If the aircraft uses self-defense jammers or releases chaff during an attack, halve the gun's hit chances. This penalty does not apply to guns directed by an electro-optical (EO) detection system, or by optical-mode (OP) fire control.
• In low visibility (40% or less), halve the hit chances of all guns with optical-mode (OP) fire control.
• If a large-caliber gun (76mm or larger) fires during the second fire phase of an engagement turn, halve its hit chances.
• High-altitude target: reduce hit chances by 1/4.
• Target with Very Small or Stealthy RCS: reduce hit chances by 15%.
• Three-second rule: if a missile is destroyed less than 3 seconds' flight time from its target, the target will suffer fragmentation damage from the explosion of the missile's warhead. To find the fragmentation danger range (in nm), divide the targeted missile's distance covered during one engagement-turn movement phase by 5. If the missile is destroyed at that distance or closer, it will inflict fragmentation damage (see section 7.3.1.2, Air Bursts).

Many missiles are so fast they can fly through a gun system's engagement envelope in a single engagement turn. Such missiles are frozen so that short-range weapons can fire at them (see 2.2.4), but it can matter (because of the three-second rule) to know at what range the missile was shot down.

To find out at what range a short-range gun destroyed a high-speed missile, compare the die roll to the hit %. If the die roll is low enough to have destroyed the missile at the farthest range, the missile was shot down at maximum range. If the roll indicates destruction at half the range, the missile is destroyed at 50% of the gun's maximum range.

• A gun's hit chances can never be increased above 0.85. The minimum hit chance is 0.01.

Example 1: an SS-N-2A vs. an Israeli Sa'ar patrol boat. The SS-N-2A is a slow missile (under Mach 1.5) moving at low altitude. An Israeli Sa'ar has an OTO Mk1 76mm/62 gun with a maximum range of 3.8 nm.

Range Band	Range (nm)	Hit Chance
Short	0-1.9	0.35
Long	1.9-3.8	0.20

Because the SS-N-2A is a slow-moving target above very low altitude, non-maneuvering, the gun's hit chances at short and long range are doubled to 0.70 and 0.40 respectively.

Example 2: Falklands Bomb Alley. An Argentine A-4Q Skyhawk attempts a very-low-altitude bombing run against a British Type 42 DDG. The Type 42 has an Mk8 114mm/55 gun and an Mk4 20mm/80 gun that can engage the target. Because the A-4 is at very low altitude, their hit chances are halved.

Gun	Range Band	Range (nm)	Hit Chance	Modified Hit Chance
Mk8 114mm	Short	0-2.4	0.25	0.12
	Long	2.4-4.8	0.05	0.02
Mk4 20mm	Short	0-0.6	0.15	0.07
	Long	0.6-1.2	0.05	0.02

Example 3: the three-second rule. A US Spruance-class destroyer is attacked by a P-700 Granit [SS-N-19] missile. The Mk15 Block 1 Phalanx has a hit chance of 0.75 at 100% range and 0.45 at 50% of maximum range (1.2 nm). The player rolls 35 on 1D100, low enough to hit at maximum range. Had he rolled 65, he would have hit it at half range, i.e. 0.6 nm.

The Phalanx hits and detonates the missile 1.2 nm from the ship. However, because the P-700 is a Mach 2.5 missile, it is close enough (6.9 nm/movement phase / 5 = 1.4 nm) to "shower" the destroyer with fragments from the explosion. The P-700 inflicts 200 damage points (DP) if it hits its target.

Using the air-burst rules (7.3.1.2), divide the 200 DP by 5, giving a modified total of 40 DP that causes 3D6 critical hits, but which do not directly reduce the ship's damage points. Consequently, the weapon inflicts between 5 and 30 critical hits, using the air-burst column of the critical hit types table.

6.4.1.2 Surface-to-Air Missiles (SAMs). Surface-to-air missiles can be fired during any fire phase and move like aircraft. Annex D gives SAM characteristics and performance. As with AAMs (see section 6.3.3), surface-to-air missiles have an air-to-air value representing their relative ability to engage an aircraft.

Once a missile reaches its target (during the movement phase), the attack is resolved using the air-to-air combat resolution table (section 6.3.3). Subtract the target's defensive ATA value from the missile's attack value. The resulting number is looked up on the air-to-air combat resolution table to determine the hit percentage. This percentage may be modified according to the conditions listed on the air-to-air combat table. Attack effects occur simultaneously, after all attacks in that phase have been resolved (completed).

6.4.1.3 Range Measurement. The range to an air target is the range at the end of the movement phase.

If a SAM destroys a missile less than 3 seconds' flight time from its target, the target may suffer fragmentation damage from the explosion of the missile's warhead and structure (see the three-second rule).

6.4.1.4 Crossing Target. If the targeted aircraft or missile crosses an arc of 45° or more, from the firing ship's point of view, during a movement phase of an engagement turn, the aircraft or missile is a crossing target. A crossing target is hard to hit because it has a very high bearing rate relative to the firing ship. The hit percentage against a crossing target is half the hit chances after all other modifiers have been applied. Round all fractions to the nearest whole percentage.

Example: a carrier (CV) is attacked by a Walleye II, a very small (V Small) target. Ships 1 and 2 are both armed with NATO Sea Sparrows, a 3rd-generation SAM with an ATA value of 4.0. The target's ATA value is 0.5 (unmanned target) + 1.0 (very small target against a 3rd-generation missile guidance system) = 1.5. The difference is 4.0 − 1.5, or +2.5. The hit chances (using the air-to-air combat resolution table from section 6.3.3) are 55%. From Ship 1's point of view, the target moves through an angle less than 45° in one phase, so it is a normal target for it, and its hit chances remain at 55%. For Ship 2, fitted with the same SAM type, the shot will be harder, since the missile crosses an angle >45° from its point of view. Because it is a crossing target, the hit chances will be 55%/2 = 28%.

6.4.1.5 Defensive Battery Ranges. Anti-aircraft weapons with a range shorter than the distance an air target covers in one engagement turn can only fire once against that target. Because air movement is split into 15-second phases, an air target will only appear at 15-second intervals along its flight path. It can happen that the target stops moving within a defensive battery's weapon range, then moves again next turn and is still under defensive fire. In H4, each weapon shot represents a 15-second fire phase; if the weapon's speed is high enough, it will only remain within the defensive weapon's engagement envelope for 15 seconds or less, and can only be hit with a single shot.

Example: an AS-1 Kennel, fired at a Knox-class FF, moves 2.5 nm per movement phase. The Mk15 Phalanx has a range of 0.8 nm. The Phalanx will only be able to fire on the AS-1 once it has closed to within range of the targeted ship, even if the AS-1 ends its movement within 0.8 nm of the ship. The ship's Mk42 127mm/54 gun will be able to fire on the AS-1 more than once, since the missile will need more than one movement phase within that gun's range (5.2 nm).

6.4.1.6 Sea-Skimming Targets. Air units (aircraft and missiles at an altitude of 30 meters or less) flying at very low altitude are very hard to hit. Not all SAM systems are designed to attack targets at this altitude, due to problems locking a radar onto the target amid sea clutter (which is precisely why missiles fly so low in the first place). Any surface-to-air missile system with a very-low minimum altitude noted in Annex D can engage sea-skimming targets. If a SAM system is not noted as sea-skimmer capable, add 4.0 to the target's ATA value, in addition to other applicable modifiers, then resolve the attack normally. Anti-ship missiles with sea-skimmer capability are noted in Annexes D or G.

Some air-to-air missiles also have problems with sea-skimmers. SARH and IRH missiles cannot distinguish the missile from its reflection on the sea surface. Imaging infrared-guided missiles and active-radar-homing AAMs can attack sea-skimmers normally.

Furthermore, some artillery pieces have been specifically designed to engage sea-skimming targets and so suffer no penalty when engaging them. These are noted as "sea-skimmer" capable in the remarks column of Annex C.

6.4.1.7 Missile Terminal Maneuvers. Some anti-ship missiles carry out terminal evasive maneuvers just before striking. Some missiles, such as the French Exocet MM40 Block II and the Russian P-270 Moskit [SS-N-22], perform rapid S-turns from the moment the missile's guidance system allows it until very shortly before impact. Other missiles, like the Harpoon 1A, perform a terminal popup maneuver. With this type of maneuver, the missile abruptly climbs to a couple hundred feet (low-altitude level), then dives onto the ship below.

While the missile is maneuvering, the defending ship fires on the missile with a -15% penalty for guns and a +1.5 ATA modifier for missiles. If the missile performs a terminal popup maneuver, it is treated as being at low altitude rather than as a very-low-altitude target. Anti-ship missiles with a very small or stealth RCS are treated as small targets while maneuvering.

Players can make sure that when they fire a maneuvering missile, it is not within the defensive weapon's minimum range. Anti-ship missiles with terminal maneuver/popup capability have this noted in the remarks column of Annexes D and G. The capability may be optional or automatic.

Example: a P-270 Moskit [SS-N-22] anti-ship missile acquires and begins homing on a Spruance-class DD. The Spruance has a NATO Sea Sparrow system, with an ATA value of 4.0, and an Mk15 Phalanx CIWS. The Spruance's defense system hit probabilities are therefore:

Moskit's defensive ATA: 0.5 + 1.0 + 1.5 = 3.0 +1.0 for missile speed (1,000 knots or more) +1.5 for terminal maneuvers NATO Sea Sparrow's ATA: 4.0 Difference = 1.0, giving a Ph of 40% per missile

Mk15 Phalanx Ph at short range (0-50%) = 80% −10% for missile speed (1,000 knots or more) −15% for terminal maneuvers Final Ph = 80 − 10 − 15 = 55% per salvo

6.4.1.8 Terminal-Dive Missiles. Many Russian cruise missiles fly at high or very high altitude until they are above the target, then dive onto it. In game terms, this dive occurs during the engagement turn in which the missile reaches the ship. Diving onto the target forces the ship's defensive weapons to fire at high elevation angles, reducing their effectiveness. Treat all terminal-dive missiles as crossing targets (except for US ships fitted with NTU and the Aegis system, which can fire their SAMs normally). Terminal-dive missiles have this noted in the remarks section of Annexes D or G.

6.4.1.9 Small-Arms Fire Against Aircraft. Infantry units embarked on ships can use their automatic weapons to attack aircraft. While not very effective, it distracts the pilot and boosts troop morale. Effective range is 0.20 nm, with hit chances of 2% at very low altitude and 1% at low altitude. Fire is considered local control (no fire director) and ignores all target modifiers. Shooters can engage any number of targets in 1 engagement turn, but can only attack each target once during the turn. Small arms cannot engage missiles.

6.4.1.10 Anti-Air Fire Restriction. No unit may open fire with a weapon or guide a missile against an air target during the engagement turn in which it reaches another friendly ship. Imagine an anti-aircraft gun firing on a missile heading toward another friendly ship. Most of the rounds aimed at the missile will miss it, and many will hit the other ship, even if the missile is shot down. The same happens if a SAM is fired at the missile. A ship presents a larger radar image than a missile. There is therefore a greater chance that friendly fire hits the ship than that it hits the enemy missile.

6.4.2 Anti-Surface Warfare (ASuW) covers missile and gun attacks against hostile surface ships. Surface gun duels are rare; usually, the outcome of combat results from a long-range missile shot directed by helicopters from the firing ship. Most often, survivors break off rather than risk a random counterattack. However, as events in the Persian Gulf showed, having a gun is a good thing for a ship that must operate in a littoral warfare environment.

6.4.2.1 Surface Gunnery. When a ship attacks another surface ship with artillery, the player must choose the type of ammunition he will use. Most modern gun ammunition can be fuzed for airburst or impact detonation, and for some weapons, the player must choose between HE or AP ammunition. Airbursts scatter high-velocity fragments that damage mounted weapons and detection systems, but probably won't sink the ship. Impact-detonating shells punch holes in the ship that can damage vital points like the engine room and can let in water. Armor-piercing (AP) rounds always explode after impact (i.e. not in the air) and do not do as much damage as high-explosive (HE) rounds, but have a greater probability of penetrating the target's armor.

To carry out a surface gunnery attack, start by measuring the distance from the firing ship to the target, then check the gun's range referring to Annex C1, naval surface artillery. Each gun has a short-range band between 0-50% of its range, and a long-range band between 51 and 100% of its range. Guns perform better at short range than at long range. Their hit probabilities are higher, they inflict more damage, and they penetrate a greater thickness of armor (see section 7.3). Surface gunnery attacks are resolved during the fire phase of the engagement turn in which they take place.

Determine the hit probabilities for the appropriate range band of the firing gun and roll 1D100. If the result is less than or equal to the hit chances, the gun hits its target. Count the number of coaxial guns firing and multiply this by the damage points that gun inflicts for that range band. The result is the number of damage points inflicted on the targeted ship. Remember that a ship can generally only engage as many targets as its fire director allows, unless the mounted gun is firing under local control. Modern warships generally have one fire director for surface-to-surface gunnery, although some have 2. The weapon line in Annex A will show the number of gunnery directors available.

Players roll once for each fire director each round, taking into account all the modifiers listed below. If the fire director is locked onto the target, all weapons it directs will hit; if not locked onto the target, all will miss. All guns, except the largest, will fire several shells in one turn, and these are statistically accounted for in the damage inflicted by a single attack.

Players do not need to track ammunition fired for each gun type. It is extremely rare for a surface gun to run out of ammunition.

Surface gun modifiers:

If target speed is 35 knots or more: −10%. If target speed is 10 knots or less: +10%. Target has a very small or stealth RCS: −15%.

6.4.2.2 Surface-to-Surface Missiles. Surface-to-surface missiles (SSMs) are only fired during the planned fire phase. They cannot be fired during the reaction fire phase, since setting up a flight path for an SSM takes some time, even if the target's exact position is known. Properly organizing a coordinated, synchronized strike can take several tactical turns, and possibly even an intermediate turn. Missile attacks against ships are not resolved until the resolution phase.

Unless otherwise noted in Annex A's remarks section, each separate SSM weapon system on a ship can only fire on one target at a time. It can fire as many missiles as its rate of fire allows, but they must all be aimed at the same target.

Depending on the missile's guidance system, the player must select its options before launch. Some can carry out evasive maneuvers; others can fly to waypoints, letting the missile attack from a different angle to conceal the launcher's position. The activation point or launch mode (RBL or BOL) must also be chosen before launch. Section 5.3 covers each system's capabilities and how they behave in flight.

After launch, a missile will move at its speed along the course set by the player. If it reaches the target and acquires it, as described in 5.3, then resolve all defensive fire against it, as per 6.4.1.

If the missile survives the defensive fire, players roll to see if it hits during the resolution phase.

Each anti-ship missile is classed by its guidance system's generation (level of development), in Annex D for surface-to-surface missiles, and in Annex G for aircraft-launched anti-ship missiles. Each generation is more advanced than the last, giving it a better chance of hitting its target and greater resistance to countermeasures.

Each ship may also be fitted with jammers and decoys, designed to fool and disrupt an incoming missile. These are also classed by generation. A ship's jammers or decoys are noted in the countermeasures section for each ship listed in Annex A. At the same time, note its RCS signature — from large to stealth.

Consult the anti-ship missile attack table (p. 6-5). There are 5 sub-tables, one for each target signature. Countermeasures help a small ship more than a large one, so the ship's apparent size from the missile's point of view matters.

Find the generation of the ECM system used, then the generation of the missile's guidance system. If the targeted ship has no ECM, use the missile generation value in the 2nd column. The 3rd column onward gives the missile's hit chances on 1D100 if no countermeasures are used. The next 3 columns to the right give the hit chances for each missile guidance generation, if a jammer is used, if decoys are used, or if both are used together. The player does not need to give a specific order to use countermeasures. As soon as a ship has them, it uses them.

Under the column for the combination of countermeasures used, find the hit chances (Ph) for the appropriate missile generation. Roll 1D100 for each missile of that type attacking. If the result is less than or equal to the hit chances, the missile hits the ship. If it misses its target, it will continue on the same course during the next movement phase. If it acquires another target, it will attack it as long as it has fuel. See also section 5.3.15, reattacking anti-ship missiles.

Example: the Exocet that sank Atlantic Conveyor during the Falklands War was fired by an Argentine Super Etendard at the frigate HMS Ardent. Ardent, using chaff, decoyed the missile and survived. However, the missile, seduced by the chaff cloud, flew through it and found Atlantic Conveyor right in front of it.

6.4.2.3 Coastal Batteries. Land-based artillery, missile batteries, and even land-based torpedoes can be used against ships within their effective range. The artillery must either have a line of sight, or be controlled by a forward artillery observer who himself has line of sight to the target. The observer must be in direct contact with the battery or its fire direction center (FDC). The battery's most forward observer must have line of sight to the targeted ship and must maintain it throughout the attack.

Base hit chances are 15% up to half range, then 7% up to maximum range. The modifiers from section 6.4.2.1 apply. The hit chances are for a 6-gun battery, not a single gun. The chances are low compared to naval guns, because land-based artillery is not designed to engage naval targets. It has no radar, no optical fire-control system, nor the gyrostabilizer normally associated with naval artillery. The dispersion of individual guns also reduces their accuracy.

The battery can fire for up to 3 minutes (one tactical turn) in rapid-fire (salvo) mode, after which it must switch to sustained fire due to crew fatigue. This halves the hit chances.

Specialized coastal-defense guns, now rare, are still used by some nations. They are generally supported by a command post housing the fire-control system and detection systems, usually radar or IR. Most are fixed gun batteries, but mobile systems such as the Russian BERG system are commercially available. Unless the scenario states otherwise, treat the coastal-defense gun as a naval gun for attack resolution.

Missile attacks are resolved using the rules in section 6.4.2.2, and torpedo attacks using those in section 6.4.3.1.

6.4.2.4 Anti-Tank Weapon Fire Against Ships. Most anti-tank weapons can attack ships close to shore. This includes some anti-tank guided missiles, anti-tank rockets, tank guns, and recoilless rifles. The attacking unit must have line of sight to the ship before it can fire.

Modern anti-tank guided missiles (ATGMs) have a range of 2.0 nm and an 85% hit probability. If an ATGM hits and penetrates heavy armor, it inflicts 2 damage points.

Anti-tank rockets are unguided man-portable weapons. Although they seem like strange weapons to use against a ship, during the Iran-Iraq War, Iranian Revolutionary Guard units aboard fast Boghammer boats often used this type of weapon to harass tankers. Anti-tank rockets have a maximum effective range of 0.25 nm, and their base hit chances are 40% up to half that range, then 5% up to maximum range. If a rocket hits its target, it penetrates medium armor and inflicts 1 damage point.

Modern tank guns typically range from 100 to 125mm caliber and have limited elevation. However, many tanks are fitted with IR sights and laser rangefinders that give their shots greater accuracy. A tank gun's maximum effective range is 3.0 nm, and its base hit chances are 85% up to half that range, then 40% up to maximum range. If the shell that hits its target is AP, it penetrates heavy armor and inflicts 1 damage point. If the shell is a pre-fragmented HE round, it penetrates light armor and inflicts 5 damage points.

Towed anti-tank guns and recoilless rifles are local-control weapons. Anti-tank guns have a maximum effective range of 2.0 nm, and recoilless rifles 1.0 nm. Base hit chances are 30% up to half that range, then 10% up to maximum range. If a shell hits its target, it penetrates medium armor and inflicts 1 damage point.

These weapons can only fire for 2 tactical turns, after which they need to cease fire to reload ammunition and/or let the gun cool down.

6.4.2.5 Infantry Fire Against Ships. Infantry can open fire on ships within a maximum distance of 0.25 nm from the infantry's position. Hit probabilities are 2%, and no surface artillery modifiers apply. If the target is hit, it suffers a critical hit. Roll 1D10 on the critical hit table. If the result is flooding, engine room, rudder, flight deck, hangar, or thick (internal) hull, no damage is inflicted. If the location hit is armored, no damage is inflicted.

6.4.3 Surface Ship Attacks Against Submarines. Anti-submarine warfare (ASW) is the classic duel between surface ship and submersible. It is not always an even fight, with the submarine as hunter in most cases. The towed sonar array and the helicopter are a modern ship's best tools for finding a submarine. The ship will then fire torpedoes, standoff weapons, or order the helicopter to attack it with its own weapons.

Several types of ASW weapons can be fired from ships: mortars, conventional or nuclear depth charges, homing torpedoes, and standoff weapons (depth charges and guided torpedoes carried by a missile to the target, then parachuted into the water).

6.4.3.1 Surface-Launched Torpedoes. Torpedoes can only be fired against already-detected targets, with a calculated passive firing solution. All ASW torpedoes listed in Annex F are acoustic-homing weapons (some are wire-guided) unless otherwise specified. Details on torpedo guidance systems are given in 5.5.3 and 5.5.4.

Nowadays, guided torpedoes are the rule rather than the exception. They can be used to attack surface ships as well as submarines, and can be fired against either type of platform. The precise rules for using homing torpedoes are given in section 6.5.2.2. These rules must be used for attacks by surface ships against submarines or other surface ships.

The distance covered and the torpedo's range are measured from the geographic point of launch to the torpedo's current position. If the distance covered by the torpedo since launch exceeds its stated range, it automatically misses its target. Modern torpedoes leave no wake, but the propeller makes as much noise as an active acoustic guidance system, which can be heard by passive sonars. Torpedoes cannot hit hovercraft or hydrofoils while their skirt is out of the water or their hull is foilborne.

6.4.3.2 Standoff ASW Weapons. Standoff weapons are carried by a rocket to the target's position. Each standoff ASW weapon is launched and flies to the aim point like any other missile. Upon reaching it, instead of activating a guidance system, it automatically releases a parachuted homing torpedo or a nuclear depth bomb.

While a standoff weapon has the advantage of being able to attack a submarine at good range, the payload must be precisely positioned or it will be wasted. A torpedo must be positioned close enough to the submarine to acquire and home in on it. Even a nuclear depth bomb must be positioned near its target or it won't destroy it. The chances of positioning the weapon correctly depend on the accuracy of the TMA firing solution (section 6.1.2), the target's range, and the weapon type.

Standoff Weapon Positioning Table

Range (nm)	Good Solution	Fair Solution	Poor Solution	Bearing-Only
0-5.0	0.85	0.80	0.70	0.60
5.1-10.0	0.85	0.70	0.60	0.50
10.0-20.0	0.80	0.60	0.50	0.40
20.0+	0.70	0.50	0.40	0.30

Modifiers:

• Guided weapon: +15%
• Nuclear depth bomb: +15%

To successfully guide a standoff weapon, the target must be within the firing ship's radar horizon, or be tracked by another unit (ASW helicopter) that must feed guidance data to the firing unit. For example, for a ship to use an 85RU Rastrub [SS-N-14d] at its maximum range of 28 nm, an aircraft (Hormone A, Helix A, May, Bear F, etc.) must be in contact with the submarine and send its information via data link to the ship.

To determine whether a standoff ASW weapon is correctly positioned, roll 1D100 and compare the result to the value given by the standoff weapon positioning table, based on the target's range and the TMA solution quality. Modify the hit chances if the weapon is guided and/or if its payload is a nuclear weapon. If the standoff ASW weapon is correctly positioned, the homing torpedo will automatically acquire the targeted submarine on the next detection phase. The torpedo's attack is resolved normally. If the payload is a nuclear depth bomb, then the submarine is automatically included within the weapon's destruction radius. When measuring the distance from the explosion to other units, use the targeted submarine's position as the epicenter.

If the standoff weapon is not correctly positioned, and its exact position is unknown due to the proximity of other units, determine its position randomly. For a target at 10 nm or less, the target was missed by 1D6/2 nm, and beyond 10 nm, it was missed by 1D6 nm. The direction of the miss is 1D6 x 60°.

A standoff ASW weapon can only attack a submersible within its own range, not its range plus that of the torpedo. A standoff-launched torpedo conducts a circular or helical search around its splashdown point. In reality, the maximum range will equal the standoff weapon's range, plus the search circle's radius, plus the torpedo's guidance system acquisition range. However, you will be very lucky to hit a submarine at this extreme detection range, since it does not account for circular error probable (CEP), tracking error by the ship, the submersible's movement after the torpedo enters the water, etc.

6.4.3.3 Depth Charge Attacks. Several navies still use depth charges (DC) as ASW weapons on some of their ships. Not only because they are cheap, but because they can be effective against submersibles in shallow water. Surface ships can attack submarines with depth charges dropped from deck-mounted racks or thrown by projectors (K-guns). These systems are practically the same as those used at the end of World War II or developed in the postwar period. Depth-charge attacks can only take place during the planned fire phase of a 3-minute tactical turn.

Each rack can drop up to 4 charges per tactical turn, while each projector (K-gun) can throw 2 depth charges per tactical turn. Since racks and projectors have no firing arc, the ship must maneuver over the submarine's location and drop its weapon at the right moment.

To carry out a depth-charge (DC) attack, the surface ship must have a good TMA solution and have maintained sonar contact with the submarine during the previous tactical turn. On the turn the ship carries out its attack, the submarine player must give the ship player a group of 3 adjacent depth levels (e.g. shallow, intermediate I, and II), one of which is where the submarine actually is. If the ship is fitted with a depth-search sonar, noted in the detection systems section of Annex A, the submarine player must give the attacking player his exact depth.

Once the depth information has been given, the ship passes directly over the submarine's position and drops as many depth charges as its racks and projectors allow.

If the weapon's depth setting matches the submarine's depth, the attack is valid and has a chance to hit. The base hit chance (Ph) of a DC attack equals the number of depth charges divided by 100. This number can be modified by one or more of the conditions given in the DC attack modifier table. The conditions are cumulative.

DC Attack Modifier Table

Condition	Ph Modifier
Submarine speed at 15 knots	Base Ph x 1/2
DC fitted with acoustic guidance system	Base Ph x 5
Shallow or Intermediate I depth	Base Ph x 1
Intermediate II or III depth	Base Ph x 1/2
Intermediate IV depth	Base Ph x 1/4

Once Ph has been determined, the attacking player rolls 1D100. If the die roll is less than or equal to the final Ph, a depth charge detonated close enough to the submarine for it to suffer the maximum damage inflicted by a depth charge, as given in Annex E3, depth charges.

If the die roll is greater than the final Ph but less than or equal to 2 x the final Ph value, this is a near miss, and the submarine suffers half the damage points inflicted by the depth charge. Additionally, there are limits on which critical hits a submarine can suffer from a near miss (see section 7.3, critical hits).

Example: a North Korean Romeo-class submarine has been detected by a South Korean Gearing-class FRAM II destroyer. The Gearing is fitted with 2 Mk11 Hedgehog ASW mortars and a single Mk9 depth-charge rack. The Romeo is at intermediate I depth and trying to sneak away at 4 knots. After tracking the Romeo with active sonar and obtaining a good TMA solution, the South Korean destroyer makes a pass to depth-charge it. The depth charges' hit chances (Ph) are:

Base Ph = 4/100 = 0.04 (4 DCs maximum for a single rack) Depth modifier: x 1 (target at intermediate I depth) Max damage Ph = 0.04 Half damage Ph = 0.08

6.4.3.4 Depth Charge Attack Restrictions. Ships dropping depth charges at shallow or intermediate I depth must be moving at least 15 knots or automatically suffer explosion damage equal to one charge's damage points, plus critical hits resolved on the torpedo attack table. For other depth levels, a ship may move as slowly as 5 knots and will suffer no damage from its own depth charges.

A submarine can only be attacked by depth charges from one ship every 2 tactical turns. If more than one ship tries to attack a submarine during that period, the second ship and beyond will be within the blast zone when the first ship's charges detonate. These ships automatically take damage equal to 2 depth charges if set to detonate at shallow or intermediate I depth, or equal to 1 depth charge if set to detonate at other depth levels. Critical hits are resolved on the torpedo attack table.

6.4.3.5 Ahead-Thrown Weapons (ATW). Ahead-thrown weapons (ATW) were developed during World War II to let escort ships attack submerged submarines without losing sonar contact with them. These early systems, the Hedgehog and Squid ASW mortars, were so successful that they began replacing depth charges as the preferred method of attacking submerged submarines. Many ATW systems are still used today; they are very widespread weapon systems found on all Russian- and Chinese-designed ships.

Ahead-thrown weapons fire salvos of charges over an area above the submarine's position. Hit chances are determined per salvo (not per charge). If the submarine is hit, only one charge actually hits it, since ATWs must be carefully aimed (a "good" TMA solution is required) to have a chance of hitting a submarine. ATWs cannot be fired during the reaction fire phase. Each system's base hit chances (Ph) and the damage inflicted by a single charge are given in Annex E2, ahead-thrown weapons. The base Ph is modified as follows:

ATW Attack Modifiers

Condition	Ph Modifier
Submarine speed 5 knots	Base Ph x 2
Submarine speed 15 knots	Base Ph x 1/2
Shallow/intermediate I depth	Base Ph x 1
Intermediate II/III depth	Base Ph x 1/2
Intermediate IV/V depth	Base Ph x 1/4
All other depth levels	Base Ph x 1/8

If the ATW is an ASW mortar, the projectile must make contact with the submarine's outer (light) hull to cause damage (it explodes on contact). During World War II, the system was effective enough to usually sink a U-boat with a critical hull penetration. However, the largest submarines of that era are today considered small to medium size, and modern submarine hull steel is stronger. Furthermore, submarine design has changed, and today they have a lot of empty space, so a direct hit will not necessarily have an adverse effect on submerged operations.

Consequently, if a submarine is hit by an ASW mortar projectile (the list of these systems appears in Annex E), there is a 75% chance of an automatic hull-penetration critical hit if the submarine is single-hulled. If the submarine is double-hulled, the chances of an automatic critical penetration of the inner (thick) hull drop to 50%.

The remarks section of Annex A shows which submarines are double-hulled. If a critical hit penetrating the inner (thick) hull does not occur, apply the damage points to the submarine's total and resolve any additional critical hits normally. While a critical hit affecting the inner hull would normally be randomly determined, ignore it in this case.

Example: after a depth-charge attack fails, the South Korean Gearing-class FRAM II destroyer fires 2 rounds from its Mk11 Hedgehog ASW mortar at the North Korean Romeo-class submarine. The Mk11 Hedgehog's base Ph is 0.07. It is modified as follows:

Base ATW attack Ph = 0.07 Depth modifier: x 1 (target at intermediate I) Speed modifier: x 2 (target speed at 5 knots) Final ATW attack Ph = 0.14

Even if one or both Mk11 Hedgehogs hit, there is only a 50% chance of a critical hit penetrating the inner hull, since the Romeo is double-hulled. However, the Romeo will take 7 damage points.

6.4.3.6 Anti-Torpedo Defenses (Torpedo-Killer Systems). While theoretically possible, intercepting torpedoes is much harder than intercepting an incoming aircraft or missile, because, on one hand, range measurements made with active sonar are not as accurate as those from radar, and on the other, the attacking torpedo's depth cannot be precisely determined. For straight-running and wake-homing torpedoes, this is not a problem, since the torpedo runs less than 50 feet below the surface. However, depth information becomes essential in the case of acoustic-homing torpedoes.

Detection ranges are also much shorter for sonar than for radar. This is partly offset by a torpedo's slower closing speed.

Today, there are 2 ways to destroy an incoming torpedo. The first involves using a torpedo guided onto it, hoping it detonates close enough to the incoming weapon to disable or destroy it. The second method uses a "carrot and stick" approach, luring the torpedo toward a decoy surrounded by explosive charges. This "seduce and barrage" technique is used by the Russian RPK-5 Liven [RBU-12000] system. Russian sales brochures tout an almost unbelievable effectiveness for a 1st-generation system (0.70 against homing weapons and 0.96 against straight-running torpedoes), which contradicts all the data on barrage techniques against submarine weapons. The World War II Squid system had a maximum kill probability (Pk) against a U-boat of 0.33, with the target's depth known. Consequently, it is likely that the touted performance is contractor hyperbole and cannot be relied upon.

The following table gives the estimated hit chances of barrage weapons and the only known anti-torpedo torpedo — the Mk46 Mod 7. The Mk46's effectiveness is assumed to be worse than a 1st-generation surface-to-air missile system against stable, non-maneuvering targets.

Torpedo-Killer System Effectiveness

Anti-Torpedo System	Straight-Running/Wake-Homing Torpedo	Acoustic Homing
RBUs	0.10	0.05
UDAV-1	0.25	0.15
Mk46 Mod 7	0.30	0.20

6.5 Submarine Attacks

Modern submarines fire not only torpedoes, but also submerged-launch anti-ship missiles and standoff weapons. Many submarines must also carry several types of torpedoes, some designed for ASW, others for anti-surface warfare, or simply older models still in inventory. Submarines may soon be able to engage aircraft while submerged.

6.5.1 Limitations. Submarines can only fire weapons loaded in their torpedo tubes. These must be noted by the player. Submarines can only fire submerged-launch missiles at shallow or periscope depth. They can fire torpedoes at any depth. Submarines can launch up to 4 weapons from torpedo tubes during an engagement turn, but the number of wire-guided torpedoes that can be controlled simultaneously depends on the submarine's fire-control system, as described in section 4.4.9. For other submarine launch systems, see section 5.2, rate of fire.

Reloading torpedo tubes can be done at a rate of one tube per tactical turn, up to 2 tubes for Western submarines and 4 tubes simultaneously for Russian-designed submarines. The player must write down, before the game, what each tube is loaded with, since it takes 3 tactical turns to change a tube's contents or for initial loading. Crew members assigned to the torpedo room can reload torpedo tubes as described above, or swap a tube's load at any given time (if full). Since a limited number of tubes is available, choices must be made carefully.

Torpedo Guidance Generations Table

Torpedo Generation	Description	Hit Chance	Acquisition Cone	Active Acquisition Range	Passive Acquisition Range
1	Active/passive seeker	40%	±60°	1,000 yards	500 yards
2	Improved active/passive seeker	60%	±60°	2,000 yards	1,000 yards
3	Advanced guidance system	75%	±75°	3,000 yards	2,000 yards
4	Digital guidance system	85%	±75°	4,000 yards	3,000 yards

6.5.2 Submarine-Launched Torpedoes. These rules apply to all torpedo attacks. Torpedoes must be fired against an already-detected target, ideally with a "good" TMA solution for the attack to be effective. Torpedoes cannot hit hovercraft or hydrofoils while their hull is out of the water or foilborne.

The torpedo guidance system type is given in Annex F. The various torpedo guidance systems are described in section 5.5. Homing torpedoes can be used to attack submarines or surface ships, and can be launched from several platform types.

The distance covered and the torpedo's range are measured from the geographic point of launch to the torpedo's current position. If the distance covered since launch exceeds its stated range, it stops and automatically misses its target. Modern torpedoes leave no wake, but the propeller makes as much noise as an active acoustic guidance system, which can be heard by passive sonars.

6.5.2.1 Straight-Running Torpedoes. Torpedoes without a guidance system are called straight-running torpedoes. They are set to follow a particular course, which, with luck, crosses that of their target. They are normally fired in salvos. A straight-running torpedo will never hit a submerged target below periscope depth.

To carry out a torpedo attack, the player must launch them toward a point where they will intercept the moving target. The intercept course is calculated automatically by the fire-control system. The player may also choose the firing direction himself, if he believes the target is about to maneuver. The course must fall within the torpedo tube's firing arc plus the torpedo's 120° gyro-angle capability.

On each movement phase following the turn they were fired, the torpedoes move at their stated speed in a straight line along the firing direction or the corrected intercept course. Depending on the target's maneuvers after launch, it may or may not be at the predicted intercept point. Furthermore, any other ship (friendly or enemy) may be struck by the torpedo if it lies in its path.

If a torpedo salvo comes within 0.25 nm (500 yards) or less (Note: see optional rule below) of any potential target, that unit is attacked by the salvo, and the torpedo attack is resolved against it.

Torpedoes move like any other ship or submarine. If it appears the torpedo salvo has a chance of crossing a ship's course, use proportional movement to see if the torpedoes pass close enough to resolve the attack. If there is no referee, the players will need to plot movement one tactical turn ahead.

Torpedo Danger Zone Sizes (optional rule). Since a torpedo salvo spreads out slightly in a fan as it moves from its starting point, the size of the danger zone depends on the number of torpedoes fired and the distance they travel. Instead of a 500-yard danger zone, use the size given by the torpedo danger zone table.

Torpedo Danger Zone Table

(See table in Annex; the zone widens with salvo size and range traveled.)

If the weapons come close enough to a valid target, players must determine whether one of them hits it. First, determine the targets' aspect, or their apparent size from the incoming torpedo's point of view. Use the target aspect diagram on page 6-32, after calculating from which direction the torpedo approached its target. Then look up this aspect — broad, quarter, or narrow — and cross-reference it with the ship's size on the target aspect table. This gives the target's effective size.

Target Aspect Table

Target Aspect	Large	Medium	Small
Broad	Large	Medium	Small
Quarter	Medium	Small	V Small
Narrow	Small	V Small	V Small

A salvo will normally only produce one hit. If the target is medium size or larger, or if there is another potential target within the weapon danger zone (section 6.2.3), carry out a second attack using the number of torpedoes that missed the original target, divided by 2 and rounded down, as a new salvo.

6.5.2.2 Homing Torpedoes. A description of the various torpedo guidance system types and acoustic countermeasures is given in section 5.5. This rules section covers launching homing torpedoes and resolving the attack once they reach their target.

Once a unit has a firing solution, it can fire a torpedo during the planned fire phase. Unlike guided missiles, torpedoes can be launched during the reaction fire phase, in snapshot mode.

Before launch, the firing player must record the torpedo's target, its course (which may be noted as "intercept" or as a fixed direction), its depth, and its activation point. This is the point in the torpedo's run at which the weapon will activate its own detection systems. If the torpedo acquires a target in passive mode, it will automatically switch to active mode and home on it.

If the torpedo is wire-guided, the firing player must note whether the wire will be cut after launch. See section 5.5.4 on wire-guided torpedoes for a description of their characteristics.

After launch, homing torpedoes move toward the target at their set speed level. As described in section 5.5.3, homing torpedoes will move in a straight line toward the target, or circle in the water around their entry point searching for a target.

Homing torpedoes have an "acquisition range," i.e. a distance from which they can detect the target and lock onto/home in on it. As the weapon moves through the water, the guidance system is located forward and takes the shape of a cone. The cone's angle and range depend on the detection system's generation. The torpedo guidance generations table gives the acquisition cone size for each guidance system generation. Acquisition range may be increased or reduced by environmental or target characteristics. The modifiers are given in section 5.5.6.

Once the torpedo has a target within its acquisition cone, during the detection phase, the torpedo will automatically detect it and lock onto/home in on it. If the torpedo has dual-wire guidance and an intact wire, it will signal the acquisition to the controlling ship. If the torpedo's guidance system is passive, it will switch to active mode. If the torpedo is not at its maximum speed, it will accelerate to its highest speed.

On each movement phase after detection, the torpedo will move toward the detected vessel at its maximum speed. If the targeted unit changes course or maneuvers, the torpedo will turn to follow it. The torpedo's turn will be tighter than that of any submarine.

On each movement phase in which a torpedo reaches its target's position, the attacking player must roll to see if the torpedo hits its target.

6.5.2.3 Homing Torpedo Hit Chances. The base hit chances for an acoustic-homing torpedo are given by the torpedo attack table. They depend on the guidance system's generation, whether or not the torpedo is wire-guided, and the TMA solution quality. Because the game gives players access to much more information than they should have, torpedo hit probabilities are modified to account for the fact that data on the submarine's target location may be very poor. While the torpedo, on the playing surface, moves perfectly toward the target, in reality this may not be the case when the firing solution was not good enough at the moment of firing. Consequently, when the torpedo carries out its attack, modify the hit probabilities with the values applicable to the target's range and the TMA solution quality at the moment of firing.

Homing Torpedo TMA Solution Table

Range (nm)	Good Solution	Fair Solution	Poor Solution	Bearing-Only
0-2.5	1.0	0.90	0.80	0.70
2.6-5.0	1.0	0.80	0.70	0.60
5.1-10.0	1.0	0.70	0.60	0.50
10.1-20.0	1.0	0.60	0.50	0.40

Torpedo hit chances can also be reduced by the target's deception attempts (decoys) or evasion. This reduction is shown in the 3 columns to the right of the base chances on the homing torpedo attack tables.

One column shows the Ph reduction from the target's use of countermeasures alone, another shows the Ph reduction from evasive maneuvers alone, and the third shows the Ph reduction from both together.

To use the evasion modifier, once the torpedo has been launched, the target must undertake at least 2 of the following 3 actions:

• increase speed to at least 20 knots,
• change course by at least 45°,
• change depth by at least one level.

If the target can meet 2 of these conditions before the torpedo reaches it, use the evasive maneuvers column of the homing torpedo attack table. If the target deploys countermeasures, use the anti-torpedo ACM column, and if it both maneuvers and deploys countermeasures, use the last column.

• If the target is large size, add 20% to the hit chances, regardless of its movement.
• Torpedoes cannot hit hovercraft or hydrofoils while their skirt is out of the water or their hull is foilborne.

6.5.2.4 Reattacking Homing Torpedoes. Homing torpedoes have, from their earliest days, had a reattack capability should they miss their first pass. If a torpedo misses its target, and there is no other visible target within its acquisition cone, it moves 1,000 yards past the target, then executes a reattack maneuver. Furthermore, if it is a wire-guided weapon with an intact wire, the firing submarine can guide the weapon back toward its target.

For acoustic-homing torpedoes, the reattack maneuver is a 500-yard-diameter circle for 1st- and 2nd-generation weapons, and 1,000 yards for 3rd- and 4th-generation. If the target is reacquired, carry out the reattack as described in section 6.5.2.3.

For wake-homing torpedoes, all generations continue on for up to 500 yards past the target, then execute a reverse course over 1,000 yards.

The probability of reacquiring the target equals the torpedo's Ph and must be checked every tactical turn, during the detection phase, for as long as the weapon is still functioning. If there are ACMs (excluding passive-sonar jammers) within the acquisition cone along with the target, use the appropriate anti-torpedo-ACM-only column when rolling to determine whether reacquisition occurs. If the TMA solution at the moment of firing was poor or was a bearing-only launch, subtract 15% from the hit chances.

If the torpedo's attempt to reacquire the target fails, and there is a mobile submarine simulator within the torpedo's acquisition range, check whether the torpedo acquires the mobile simulator using the same procedure described above. If the torpedo acquires the mobile simulator, it will lock onto and home in on the simulator and try to attack it. Resolve any attack on the mobile simulator using the anti-torpedo ACM column. If the torpedo hits the mobile simulator, it is destroyed. If it fails to acquire any target, it will continue searching on a circular course until it runs out of fuel or, if the wire is intact, until a new intercept course is given to it.

Example: an Akula I SSN is attacked by an improved Los Angeles SSN with 2 Mk48 ADCAP torpedoes (4th generation) with a fair solution. The Akula I hears the torpedoes as they switch to active mode and deploys 3rd-generation ACMs, a mobile decoy launched from a torpedo tube, and counterattacks with 2 USET-80 torpedoes (3rd generation), unguided and fired bearing-only. The range at the moment of firing is 3.0 nm, and the Mk48 ADCAPs' wires are intact. The Mk48 ADCAPs' hit probability against a target attempting an evasive maneuver and using ACMs is 62%. However, since the improved LA fires with a fair solution, its hit probabilities are multiplied by 0.8 (range = 2.6-5.0 nm and fair solution), giving a final probability of 50%.

On the other side, the Akula I's torpedoes are less effective. Assuming the improved LA does not attempt an evasive maneuver but deploys 3rd-generation ACMs, the USET-80s' base hit probabilities are 49% (3rd-generation non-wire-guided torpedo against 3rd-generation decoys only). But because the Akula fired bearing-only, the hit probabilities are multiplied by 0.6, giving final hit chances of 29%.

6.5.3 Submerged-Launch Anti-Ship Missiles

Harpoon, Tomahawk, SUBROC, SM39 Exocet, P-70 Ametyst [SS-N-7], P-120 Malakhit [SS-N-9], P-700 Granit [SS-N-19], P-800 Oniks, Novator Alpha, Kh-35 Uran [SS-NX-25], and the SS-N-15/16 can all be fired while submerged if the submersible is designed to carry them. They must be fired by the submarine at shallow depth and at a speed of 3 to 15 knots. For anti-ship missiles, the target must be actively or passively tracked, and a good or fair solution must have been calculated before a missile can be launched in RBL mode. The missile can be launched in BOL mode with any TMA solution quality. However, the BOL penalties apply (section 6.1.1). For standoff ASW weapons, such as the SS-N-15/16 family, see the standoff ASW weapons section (6.4.3.2) for details. A missile launch may reveal the submarine's position by visual, sonar, or surface-search radar means. The missile should not be placed on the playing surface until detected, to avoid revealing the submarine's position.

6.5.4 Submarine vs. Submarine Attacks. Submarines can attack other submarines using torpedoes or standoff ASW weapons. The procedure for such attacks is the same as for torpedo attacks fired by submarines against ships, or for standoff weapon launches from surface ships.

Electronic Warfare (EW). Given how rapidly electronic countermeasures (ECM) and counter-countermeasures (ECCM) have evolved over the last 20 years, it was no longer possible to model anti-ship cruise missiles (ASCM) with a single hit probability (Ph) against a generic ECM system. That is why, in H4's ASCM engagement model, there are now 3 technological generations of missile guidance systems, each with a fixed Ph against a target using no ECM. However, in a more ECM-intensive environment, hit chances vary based on the ECM system's technology level and the target's radar size.

In today's high-tech world, EW looks more like a game of chess than yesterday's boxing match. The very first approach considered was powerful jammers and decoys with larger RCS. Unfortunately, the "bigger is better" approach now backfires on the defender. A jammer emitting steady, high-power noise is exactly what an advanced ASCM like the Harpoon needs to pick up on. For the Harpoon, this has the same effect as throwing an electronic hunting dog straight at a rabbit — the missile heads right for the jammer. Expendable decoys like chaff have gradually improved and can now produce a reasonably large and, hopefully, attractive radar target for the missile. There's just one problem: chaff clouds are essentially stationary objects. Modern missile guidance systems want to see movement; and missile designers have arranged for the big, stationary radar target to be ignored in favor of the smaller radar target trying to leave the area at over 30 knots.

Advanced jammers and decoys don't rely on brute force to seduce a missile away from the ship. Instead, they are used in a delicate, subtly orchestrated combination to deceive the missile's guidance system. Rather than trying to blind the missile's seeker with a lot of noise, modern jammers use complex pulse sequences to slowly walk the guidance system's aim point away from the ship. Advanced expendable decoys, like the Australian Nulka countermeasure, can electronically generate a more realistic, because moving, radar target. Basically, the Nulka is a small, autonomous mini-helicopter fitted with a highly sophisticated transmitter that many ASCMs will find nearly irresistible.

Unfortunately, none of these sophisticated modern systems will do any good if the targeted ship has an RCS comparable to a giant hangar. Imagine that an ordinary Ford pickup truck is a basic naval frigate. If it's fitted with an ECM device, this frigate can produce a Dodge pickup as a decoy. Once close enough to read their license plates, the missile will have very little time to choose between the Ford pickup and the Dodge. Suppose that today, a carrier is an 18-wheel Peterbilt tractor-trailer. You can't hide a semi-truck behind a pickup. It just won't work. That's why RCS-reduction technology has become so important in naval combat today. When stealth is used together with advanced ECM systems, the modern surface ship has a good chance of dodging the smart projectile.

6.6 Directed-Energy (Laser) Weapons

6.6.1 The Laser Dazzle Sight (LDS) is a defensive laser system designed to force an enemy pilot to abort his attack run. It is a manually-aimed device that can be mounted on a ship's upper deck. It reportedly equipped HMS Hermes, Invincible, Coventry, Beaver, Brazen, Brilliant, Broadsword, and Argonaut during the Falklands War, and has been seen on Type 22s, and on Leander- and Invincible-class ships. An equivalent device (possibly also used as a detection system) equips the Russian Sovremenny-class destroyers. The abbreviation LDS may be used to refer to this type of system.

6.6.2 LDS Effectiveness. An LDS is treated as a mounted weapon without a fire director. It has a range of 1.0 nm, and a Ph of 40% if directed, or 10% if manually aimed or under local control.

An LDS is only effective against a manned aircraft attacking the ship carrying the weapon. It may be used against targets at low or very low altitude (it can fire at sea-skimmers). Since it is an optical weapon, its range is affected by the weather visibility factor (Annex N), i.e. at 50% visibility, its range is halved. Each mount is assumed to be fitted with a night-vision system allowing nighttime engagement. Assume that the combination of this weapon and the targeted pilot's eyes adapting to darkness increases its effective range by 150% at twilight and x2.0 at night. A hit consists of the cockpit being illuminated by the laser beam.

6.6.3 LDS Results. A hit will blind the pilot and flight crew for 1D10 tactical turns. There is a 40% chance the aircraft crashes if hit at very low altitude, and 5% if at low altitude at the moment of the hit. During this time, the aircraft must fly in a straight line, climbing to low altitude if it was at very low altitude. Additional hits (while the crew is already blinded) have no effect. The pilot and copilot cannot take any action while blinded, except to maintain the aircraft's altitude.

6.7 Electronic Warfare

Because of the complex and highly classified nature of electronic countermeasures (ECM), Harpoon 4 uses a simplified approach, folding ECM effects into weapon hit chances and radar detection capabilities. Although quite a lot of information is available on most systems in service, knowledge of how they combine is limited, and the outcome of 2 sides simultaneously using chaff, repeater jammers, and flares can only be assumed. In Harpoon 4, the emphasis is on simplicity, grounded as precisely as possible in available unclassified information. This approach gives a reasonably accurate approximation of the effectiveness of electronic or acoustic countermeasures.

ECM actions (turning on jammers, deploying chaff) must be ordered during the planning phase. However, the specific tactics of their employment need not be specified; countermeasures are assumed to be used correctly.

6.7.1 Aircraft ECM. An aircraft can supplement its built-in ECM with ECM pods fitted to standard weapon hardpoints. Pods may be defensive, protecting only the aircraft carrying them, or offensive (or escort), protecting all aircraft within a set distance. Remember that visually-directed weapons, like aircraft guns, cannot be jammed.

ECM pods may only affect radar-guided weapons, or IR weapons, or have combined effects. An aircraft can carry a radar pod and an IR pod, or a combined radar/IR pod. IR pods are always defensive. An aircraft can carry as many chaff pods as its hardpoints allow. The pod's generation is given in Annex G2, along with its range if it's an offensive pod, and its weight. For example, the ALQ-131 is a 2nd-generation defensive ECM pod, weighing 272 kg.

If a unit has dual coverage, for example if a fighter fitted with a 1st-generation defensive ECM pod is also protected by another aircraft's 2nd-generation offensive jammer ECM, use the better countermeasure — in this case, the 2nd-generation device. ECM protection is not cumulative.

6.7.2 Blip Enhancer. This is an ECM deception technique used to fool the enemy. A device carried aboard a ship or aircraft amplifies its radar echo, so the enemy screen shows a larger silhouette than the ship or aircraft would actually return. This means the formation's escort ships will appear larger, and the carrier or another high-value unit cannot be distinguished from the others. A helicopter can also carry this device, and, while hovering at very low altitude, simulate a medium-size ship's radar signature.

Blip enhancers on medium-size ships make them appear as large ships, while small, very small, or stealth ships, and helicopters, will appear as medium-size ships.

Carriers, submarines, auxiliaries, and combatants smaller than frigates do not normally carry this device. Annex B, under the "sensor" heading, notes for each helicopter whether it is fitted with a blip enhancer.

Blip enhancers affect both search radars and missile guidance systems equally. However, an inverse synthetic aperture radar (ISAR configuration) cannot be fooled. Since it provides a real-time image of the radar contact, the blip enhancer has no effect. ISAR radars are noted in the remarks section of Annexes J and L.

Any player can order a unit to turn on its blip enhancer during the planning phase. During the detection phase, the ship will be detected by radar as if it were a larger target, with increased detection range. The detailed target-selection rules can be applied using the procedure given in section 5.3.14, terminal guidance.

Missiles attacking helicopters using blip enhancers will automatically miss the helicopter. Missiles carrying out a diving attack will crash into the sea. Others, depending on their guidance system, will continue on their last course, or may reattack the helicopter, again automatically missing their target.

6.7.3 Aircraft Chaff. Some aircraft are specially designed to eject large quantities of decoys into chaff corridors. Others may be fitted with pods letting them lay chaff corridors. The quantities involved with these devices are much larger than the small bursts used to decoy missiles. In some cases, they are measured in tons of aluminum-coated fiberglass flakes or silver-coated nylon threads, and can remain airborne for up to 30 minutes.

An aircraft with a chaff dispenser has its capacity given in nm. The controlling player must order the chaff release during the planning phase, and the actual release takes place during the movement phase of the same tactical turn. The distance covered by the aircraft is subtracted from the chaff capacity. The chaff barrier blocks radar line of sight regardless of the altitude the aircraft is flying at. There is no need to eject chaff corridors at very low altitude; for game purposes, it is included within the low-altitude level.

The chaff barrier is 1/4 nm wide and occupies the entire altitude level. Aircraft can fly through a chaff barrier as long as they don't spend more than 2 consecutive movement phases within the chaff cloud. If this does happen, their engines may flame out (10% chance). Chaff is not visible to the naked eye once deployed. Chaff does not block ESM detection of radar signals.

Chaff descends one altitude level every 3 tactical turns, and moves in the direction and at the speed of the wind. Unless wind speed is very high, the chaff barrier should only be moved every 10 minutes, during the intermediate turn's movement phase.

6.7.4 Long-Range Chaff Rockets. Several navies use rockets loaded with chaff as a means of deceiving enemy radars. Most chaff is then used in combination with the ship's jammers to seduce anti-ship missile guidance systems, in defense of an attacked ship. Long-range chaff is designed to dilute an enemy attack by making it open fire on non-existent targets.

Long-range chaff rockets have a maximum range of 5 nm and will last 15 minutes (5 tactical turns). They need one minute (2 engagement turns) to deploy, are fired during the planned fire phase, and become effective during the next turn's detection phase. Chaff clouds appear as small or medium-size radar contacts (roll when the chaff deploys — 50% for each size).

These chaff clouds cannot distract missiles already locked onto real ships, but can be seen by missiles in BOL mode and by missiles fired at the chaff cloud. They may be attacked by those missiles instead of real targets.

6.7.5 Floating Anti-Ship Missile Decoys. These devices are carried aboard ships and can be deployed to present false targets to enemy search radars. Sometimes nicknamed "rubber duckies," they are rubber rafts fitted with a large radar reflector. It takes a minute to deploy them, launched during a turn's fire phase. They can be set to produce a small or medium-size radar return and will keep floating until ordered to sink.

They drift with the wind at half the wind's speed, or can be towed (at the end of a very long cable) behind the ship. However, the ship's speed cannot then exceed 10 knots, or the cable will break.

6.7.6 Jamming. This section covers only "white noise" jamming. Defensive jamming, designed to reduce weapon performance, has already been covered in the sections devoted to the various weapons and combat.

There are 3 types of jamming. The 1st is self-protection or self-screening jamming, and the 2nd is standoff offensive jamming broadcast by a specialized ECM aircraft. The 3rd is "limited offensive jamming." All will reduce the effective range of enemy radars, by broadcasting a powerful radar signal. Treat an active jammer as an emitting/radiating radar for ESM detection purposes.

Offensive and "limited offensive" jammers affect all radars within their radar horizon. Defensive jammers have no effect on search radar range.

Offensive jammers equip specialized aircraft like the EA-6B and the Tu-16 Badger J. Their main purpose is to significantly reduce the range of three-dimensional radars and air-search radars. They have an effective angle of 120° (±60° on each side of the aircraft's flight direction) both ahead of and behind the aircraft. Within these arcs, radars are in the main jamming beam. Outside these arcs, they are in the "sidelobe" and suffer only reduced effects.

They also interfere with airborne interception and fire-control radars. 1st-generation jammers give a defensive ATA modifier of +0.5 to any friendly aircraft or missile within the main beam. 2nd-generation systems give a +1.0 modifier.

• Limited offensive jammers are similar to offensive jammers, but have a beam angle of only 60° (±30° on each side of the aircraft's flight path), both ahead of and behind the aircraft.
• Defensive jammers only protect the aircraft carrying them and may be built-in or take the form of pods. They have no effect on enemy search radars.

The jammer effectiveness table gives the range reductions suffered by radars within the main jamming beam and within the sidelobes. Phased-array radars are more resistant to jamming and are listed separately. Phased-array radars have this feature noted in the remarks column of Annexes J1 and L. To determine the radar range reduction, multiply the radar's range by the appropriate modifier.

Jammer Effectiveness Table

Radar System	Main Beam Range Modifier	Sidelobe Range Modifier
Phased array	0.75	0.90
Conventional	0.25	0.60

Example: the Aegis SPY-1 radar has an air-search range against medium-size targets, unjammed, of 124 nm. If a medium-size aircraft were fitted with an escort jammer or a limited offensive jammer and had targeted the Aegis ship, the SPY-1's range would be reduced to 93 nm. If a standoff jammer provided ECM support to an aircraft that itself lacked ECM capability, the SPY-1's range would drop to 93 nm.

The days of standoff jammers, however, seem numbered, as high-speed computer systems and adaptive software-controlled beam shaping make it possible for a radar system to reshape its beam pattern so it is no longer disrupted by the jamming. This lets the radar ignore the standoff jammer entirely. Note that this feature will be of no help against self-protection jammers. If a radar has this capability, it will be noted in Annex J.

6.7.7 Acoustic Countermeasures (ACM). Installing an acoustic detection system in a torpedo dramatically increases its chances of reaching its target — enough to spur the development of countermeasures, weapons designed to jam or decoy them.

Since their introduction during World War II, homing torpedoes have been steadily improved, gaining in intelligence, resistance to countermeasures, and ability to detect a target. Of course, acoustic countermeasures (ACM) have also evolved and matured. Today, they include anti-torpedo countermeasures, sonar jammers, and submarine simulators.

Anti-torpedo countermeasures will affect torpedo guidance systems but will not interfere with passive search sonars at all. Conversely, sonar jammers will affect passive sonars but will not degrade a torpedo's guidance system's ability to reach its target. Mobile simulators can affect both torpedoes and search sonars, but will do so differently, by broadcasting a submarine's acoustic signature.

An ACM's endurance depends on its size, which also determines its launch system. There are 5 ACM sizes:

1. Internal decoy ejector (3 to 6)
2. Large external launchers (6)
3. Small external launchers (3)
4. Mobile submarine simulator (15 to 21)
5. Towed ACMs

Internal launchers for sonar jammers and anti-torpedo ACMs are stationary floats and have an endurance of two tactical turns.

External sonar jammers and torpedo ACMs may be stationary floats or very-short-range mobile jammers. Small external ACMs last as long as those launched from internal ejectors (2 tactical turns), while large external ACMs can last up to 7 tactical turns. Only the US Navy's CSA Mk1 and Mk2 are classed as large external size, and are 5 or 6 inches in diameter. All others use smaller 3- or 4-inch ACM models.

When several anti-torpedo ACMs are deployed, use a single counter to mark the location. Individual anti-torpedo ACMs won't leave a distinct trace because they don't last as long and are generally dropped quickly one after another. Sonar jammers, particularly the larger ones, are generally dropped one at a time with a large distance between them, requiring a separate marker for each jammer.

A sonar-jamming ACM's jamming cone has an angle of 20° (±10°) as seen from searching sonars. The effects of jammers on torpedoes are already included in the combat models. For example, if a sonar jammer is at bearing 030°, a ship's or submarine's search sonar will be unable to hear anything but the countermeasure from bearing 020° to 040°.

Mobile submarine simulators, or decoys, are the most sophisticated ACMs and can affect both search sonars and torpedo detection systems. If launched as anti-torpedo decoys along with other ACMs or alone, they are included in the ACM section of the homing torpedo attack table. However, if the torpedo misses its target and carries out a new attack, there is a chance the torpedo will acquire the decoy instead of the submarine, because by that time there will be enough distance between the decoy and the target for the decoy to have become genuinely effective (see section 6.5.2.4).

Mobile decoys have also been designed to divert an ASW force away from the submarine as it tries to escape. The mobile decoy's endurance and effectiveness depend on its generation and are given in the mobile submarine simulator table.

Mobile Submarine Simulator Table

Simulator Generation	Endurance (hours)	Classification Probability	MAD Capability	Maximum Speed
1	1	80%	No	7 knots
2	1.5	60%	No	10 knots
3	2	40%	Yes	12 knots
4	2	20%	Yes	15 knots

Endurance is the number of hours the simulator can move at maximum speed. Classification probability is the chance that a passive sonar operator realizes the decoy is a decoy and not a real target. MAD capability means the simulator tows a magnetic-field generator that resembles a submarine's to an aircraft fitted with a MAD system. 3rd- and 4th-generation submarine simulators can perform up to 2 course changes and 2 speed changes. Older simulators are single-speed devices that follow a preselected heading.

Towed decoys are used only by surface ships. These are anti-torpedo countermeasures with unlimited endurance. Examples of this type of device include the SLQ-25 Nixie and the British Sonar 182. The effectiveness of towed decoys is included in the torpedo attack tables.

The countermeasures section of Annex A will list, for each ship, the name and generation of all countermeasures it carries. For example, the O.H. Perry-class guided-missile frigate is fitted with an SLQ-25 Nixie, a 2nd-generation towed anti-torpedo countermeasure.

6.7.8 Air Decoys. Designed to distract or fool enemy defenses, air decoys were used successfully during Desert Storm and will probably play a larger role in future wars. The US TALD is widely used by both the US Navy and Air Force. The Samson, identical to it, is used by the Israelis.

The ADM-141A Tactical Air-Launched Decoy (TALD) is the US-produced version of the Israeli Samson decoy. First delivered in late 1986, the US Navy had 4,000 units in inventory at the start of Desert Storm, including 3,600 RF decoys and 400 Chaff variants. About 130 were used. More than 20 were sometimes launched by the lead aircraft in a strike package. Some TALDs flew aircraft-like profiles, while others dispensed chaff. Their use was highly successful.

On a hostile radar screen, a TALD will look like a fighter-size aircraft (small radar contact). If launched just outside radar range, and flown on the appropriate profile, enemy radar operators will have no way of knowing which echoes are real aircraft and which are decoys.

Initially unpowered decoys, each weighs 180 kg, less than the 227 kg of an Mk82 500lb bomb. Any aircraft capable of carrying an Mk82 500lb bomb can carry the same number of TALDs, mounted the same way. They can be carried in groups of 3 on a triple ejector rack (TER) and dropped like an Mk82 bomb. The TALD's flight profile must be selected before the aircraft takes off. TALD speed can be set between 250 and 500 knots by changing the glide angle. This, of course, affects its range. It can also execute preprogrammed turns.

The TALD has a 10:1 glide ratio: if launched at 11,000 meters and 250 knots, it has a range of 68 nm, or a range of 25 nm gliding at 400 knots from 7,000 m. It can also be released in a "toss" from low altitude, giving it a range of 15 nm. See the speed and altitude diagram below.

There are 3 versions. The basic RF-TALD is used to saturate anti-aircraft defense systems. Its active (jammers) and passive (Luneberg lens) payload increases the decoy's signature from very small (VSmall) contact size to small.

The chaff TALD can dispense 80 pounds of chaff in 40 incremental ejections. It can be programmed to fly out, turn, and eject 1 nm of chaff in a line. Multiple TALDs can be coordinated, each one on the flight line of the aircraft preceding it. 30 decoys can form a 30 nm barrier that hides an air strike from surveillance radars.

An IR TALD is used as a training target for IRH-guided missiles. It cannot be used in combat.

A powered version, the ITALD, has a range of 175 nm at 460 knots and 6,100 meters, and a radar altimeter that lets it perform terrain-following flight.

Possible tactics include simply releasing RF-TALDs as the "leading wave" of a strike, drawing SAM and AA fire. TALDs can also drop chaff to mask a strike. 2 aircraft fitted with TALDs can also mimic a strike, forcing an enemy to reveal his position or drawing CAP aircraft away.

Chapter Seven – Combat Results

Weapons damage ships in various ways. First, a weapon's explosive effect will damage or destroy part of the ship's structure, including, where applicable, its (submerged) hull plating. If this happens close enough to the waterline, the explosion will open a leak. If it happens near the frames (or ribs) and keel that make up the ship's structure, and these are broken or damaged, the stress on the ship's hull may break it in two. This is unavoidable if the keel is broken.

The explosion will also propagate a shockwave through the ship. This can damage certain electrical components, tear heavy machinery loose from its mounts, or put stress on previously damaged components until they fail. The explosion's shockwave will damage the most exposed items, such as missile launchers, radar antennas, or aircraft.

Finally, most warheads will scatter fragments when they detonate. This punches more holes in the hull and can reach vital components. If the weapon is a missile, its remaining fuel may not be fully consumed, giving a good chance of starting a fire.

7.1 General Concept

Players resolve each type of attack as set out by the combat resolution summary.

Combat Resolution Summary. There is no combat during intermediate turns. For tactical turns and engagement turns:

Planning phase: no combat resolution occurs.

Movement phase (all types): air-to-air missile, surface-to-air missile, and torpedo attacks that reach their target during the phase are resolved at this phase.

Fire phase (all types): gunfire, ASW mortar fire, and depth-charge attacks occurring during this phase are resolved at this phase.

Detection phase: no combat occurs.

Missile resolution phase: anti-ship missile attacks and air attacks against ships that reach their target during the previous movement phase are resolved at this phase.

Critical hits are resolved during the phase in which they are inflicted.

7.1.1 Hits. In Harpoon 4, damage is measured in damage points. These points are used to measure both the amount of damage inflicted by a warhead and the amount of damage a ship can absorb before sinking. The bigger a ship, the more damage points it can absorb, but not on a linear scale. Larger ships gain fewer points per ton of displacement than smaller ships.

A ship's displacement and damage points are given in Annex A. The formulas used to calculate the damage-point value, based on the ship's displacement, are given in Annex Q. The damage modifier is also noted in Annex A. This is a specific factor used to reflect unique aspects of a ship's construction, such as an aluminum superstructure or a titanium hull. It is given only for completeness, since it has already been factored into determining the ship's damage-point total.

7.1.2 Critical Hits. A surface ship is a platform for the weapons and detection systems that let it fight. A ship can be destroyed by sinking, but it can also be rendered useless by the destruction of the equipment that makes it a warship. An attack aimed at destroying a ship's weapons or detection systems, even if it doesn't leave the ship badly damaged, is called a "mission kill," so named because the damage it aims to inflict on the ship will prevent it from carrying out its mission.

Damage inflicted on a vital ship component that leaves the rest of the vessel relatively unharmed is called a critical hit. This includes not only weapons and detection systems, but also the engine room, the flight deck, etc. In Harpoon 4, whenever a ship is damaged, the severity of the hit is used to determine whether there is a chance of one or more critical hits occurring.

7.3.1 Armor. Armor is useful in 2 ways. First, it reduces the amount of damage inflicted on a ship. Second, it can provide specific protection to a ship's critical areas. In the game, each function is represented by a different armor type. Both types use an armor value, given in the remarks section of the ship listing.

The letters L (light), M (medium), H (heavy), or S (special) indicate armor quality. Armor effectiveness depends on the size/caliber of the weapon used against it. There are 6 weapon classes, in ascending order of size and penetration capability. The armor effects table, on page 7-5, shows the different armor levels protecting a ship.

7.2 Damage

Damage is caused by weapon impacts and can slow or sink a ship.

7.2.1 Calculating Hit Damage. When a weapon hits, it inflicts its damage-point value on its target. Subtract the weapon's damage points from the target's total absorbable damage points. Some weapons may also inflict special damage. Weapons that hit an aircraft neutralize it by inflicting enough damage to force it to immediately abort its mission.

7.2.2 Applying Damage Effects. Damage effects, including critical hits, are applied simultaneously to both sides at the end of the phase. Damage points applied while resolving a critical hit may produce another critical hit on the next tactical turn.

7.2.3 Speed Loss. When a weapon successfully hits a ship, it inflicts a certain amount of damage points. As these points accumulate, the ship's speed drops in stages (shown in the damage and speed breakdown section of each ship's reference sheet). The top row shows the ship's damage-point level. The 2nd row is the maximum speed corresponding to each damage level (there may also be a 3rd row for submerged submarines). For example, a Spruance has a maximum speed of 33 knots at 0 damage points taken; at 42 damage points taken, its maximum speed will be 25 knots. Another 43 points of damage will reduce its speed to 16 knots. Once a total of 127 damage points has been taken, it will be reduced to 8 knots, and it will be left dead in the water (speed 0) at 152 damage points taken. It will then sink. Each ship reference sheet gives this information.

7.2.4 Submarine Forced to Surface. When a submarine is reduced to 25% or less of its original absorbable damage points, it must surface. It must remain surfaced until it has repaired half its critical hits (7.3) and its remaining absorbable damage points rise back above 25% of its original total. In a campaign game, the submarine must return to base, avoiding combat as much as possible.

7.2.5 Damage to Stealth Ships. Ships with reduced radar signatures rely on their shapes and special coatings to achieve this. If damaged, their shape is altered and they become more easily visible to radar and other detection systems.

If a ship has a reduced signature (if its signature is lower than its size class given in Annex A), and it takes 10% or more of its absorbable damage points, its signature increases by one level.

Example: a US Arleigh Burke-class destroyer is small size with a very small signature. It is hit by an Exocet missile, whose warhead inflicts 33 damage points. Since an Arleigh Burke has 208 absorbable damage points, the Exocet inflicts more than 10% of its DP, and the US destroyer, on top of its other problems, moves up to a small signature.

A ship's signature cannot increase beyond its actual size.

If a ship or submarine takes 10% of its original DP value from a submarine attack, treat it as a noisy target for sonar detection. The vessel also loses any benefit from its anechoic coating, if it had one.

7.2.6 Sinking. A ship that has taken enough damage to sink will go down in 3D6 tactical turns; the final submersion occurs during the movement phase. Submerged submarines and ships whose magazine has exploded sink immediately.

7.3 Critical Hits

Any ship that takes damage during a phase must resolve the critical hits it suffers. The number of critical hits depends on the amount of damage taken and the type of attack.

7.3.1 Causes of Critical Hits. Critical hits may be caused by direct weapon impacts, air bursts, torpedo impacts, or other damage occurring during a turn.

7.3.1.1 Direct Hits. All damage inflicted by direct impacts during a phase can cause critical hits. Direct-impact damage is damage caused by weapons not specifically designated as air bursts or torpedo impacts. The total direct-impact damage inflicted on a ship during a phase is divided by the ship's remaining absorbable damage points, after deducting the damage points inflicted during that phase. This result is called the damage ratio. Always round damage ratios down to the nearest tenth. The higher the ratio, the greater the chance of a critical hit being inflicted. The damage ratio table cross-references the damage ratio with a 1D6 roll and gives the number of critical hits inflicted.

For example, an undamaged Spruance has 169 damage points and takes 32 damage points from a missile attack. The damage ratio is 32 divided by 137 (169 − 32), or 0.23. This result is rounded to 0.2, which shows a possibility of 0 to 3 critical hits that phase.

(Damage Ratio Table: higher ratios must be extrapolated.)

Note: carrier-type ships are defined as CVs, CVHs, LHAs, CVHGs, CHGs, or any other vessel with at least half its main deck devoted to aircraft takeoff/landing facilities. A ship with one or two helipads is not a carrier.

The "weapon/flight deck" result under the "air bursts/fragmentation" column should be read as a critical hit against a mounted weapon for all ships except carriers, for which it should be read as a critical hit against the flight deck.

7.3.1.2 Air Bursts. Some weapons are designed to shower their target with high-velocity fragments from air bursts. These include SAMs used in an SSM role, ARMs, and cluster or fragmentation bombs. The Rapier, which has an extremely small warhead, is a direct-impact weapon. Guns can be set for direct-impact fire or air-burst fire, at the gunner's choice. Anti-aircraft gunfire is always treated as inflicting air-burst damage. Air-burst damage may also be inflicted if inbound SSMs are destroyed too close to their target (see 6.4.1.1, Anti-Aircraft Guns).

Critical Hit Types

Roll	Surface Warship	Carrier	Merchant/Auxiliary
1	Mounted weapon	Mounted weapon	Mounted weapon
2	Mounted weapon	Flight deck	Cargo
3	Mounted weapon	Hangar	Cargo
4	Detection system	Hangar	Flooding
5	Detection system	Detection system	Flooding
6	Flooding	Flooding	Fire
7	Fire	Fire	Fire
8	Engine room	Engine room	Engine room
9	Bridge/CIC	Bridge/CIC	Bridge/CIC
10	Rudder	Rudder	Rudder

An ARM warhead automatically uses its first critical hit to destroy any active radar it was locked onto, even if that radar has stopped emitting.

If air-burst damage is caused by a missile that exploded within the minimum range defined by the three-second rule (see section 6.4.1.1, Anti-Aircraft Guns), divide the missile's damage points by 5 before using the table below.

Air-burst weapon damage points do not need to be totaled and applied to the ship. Instead, the player rolls for each air-burst weapon that reaches its target. The result is the number of critical hits inflicted on the target.

The number of D6s depends on the warhead size:

Warhead DP	0-10	11-20	21-50	51-100	101+
Critical Hits	1D6	2D6	3D6	4D6	5D6

Example: a Russian Kh-58 [AS-11 Kilter] has a warhead inflicting 38 damage points. It hits an O.H. Perry-class frigate, detonating overhead. The attacking player rolls 3D6 and gets 10. The frigate will suffer 10 critical hits, whose nature it determines using the "air bursts/fragmentation" column of the critical hit types table. It will also take 10 damage points.

7.3.1.3 Torpedo Damage. Torpedo impacts are similar to other direct-impact weapons, but fall under a specific column of the critical hit type table.

Some torpedoes have directed-energy (DE) warheads (similar to HEAT — High Explosive Anti-Tank rounds) and are designed to penetrate deep inside the hull. Because of their design, their explosive effect is somewhat reduced for the same weight of explosive. This is already factored into the torpedo's damage-point value.

If a DE-warhead torpedo hits a submarine, there is a 50% chance of a critical hit penetrating the thick hull. If the submarine survives this roll, resolve damage normally. It may also, on this occasion, receive a "thick hull" critical hit, which will produce its full effect.

7.3.2 Critical Hit Types. There are many different types of critical hits. Once the number of critical hits has been determined, refer to the column that best describes the target (e.g. surface warship) on the critical hit types table. Roll 1D10 for each critical hit and see what type of hit is inflicted.

Example: a Spruance-class destroyer takes 3 critical hits. The player rolls 1D10 three times on the surface warship column and gets a 7, a 3, and a 6. This corresponds to a fire, flooding, and a mounted weapon. The player then refers to the following sections for each hit type to determine its effects.

If the critical hit indicates an armored area of the ship, the armor effects table will show what thickness of armor that particular weapon penetrates.

7.3.2.1 Aircraft. An aircraft has been destroyed. If an aircraft (helicopter or fixed-wing) is destroyed as the result of a "mounted weapon" critical hit against a non-carrier ship (7.3.2.13), or as the result of a "flight deck" or "hangar" critical hit against a carrier (7.3.2.6 or 7.3.2.8), roll 1D10 for each aircraft destroyed: 1-7, no additional effect; 8-9, a minor fire starts; 10 (0), a major fire starts. If the aircraft was armed (loaded with ordnance), add 2 to the die roll (a roll of 6 becomes 8). An aircraft fire can never become a severe fire.

7.3.2.2 Bridge/CIC. The ship's main control center has been damaged. The ship continues to execute its current movement orders for 1D6 tactical turns. After that, it takes 2 tactical turns to change course (the order takes effect 3 minutes after being planned). Carriers halt all takeoffs/landings for 1D6 tactical turns. This can leave an aircraft wanting to land stacked up because it's low on fuel. If the aircraft cannot find an alternate landing site either, it must be written off.

Submarines cease all attacks, lose all firing solutions, and must rise to periscope depth. A minor fire starts on the bridge (control room — PCNO for submarines) (ignored if caused by an air burst).

7.3.2.3 Cargo. The ship's cargo has been hit. The effects of this critical hit type vary considerably depending on the cargo type and the weapon type. Consult the cargo damage table for possible effects.

7.3.2.4 Engine Room. The ship's machinery (propulsion plant) has been damaged. Reduce the ship's maximum speed to the next lower level (on the damage and speed breakdown track) due to damage to the engine/propulsion plant. A minor fire starts in the engine compartment.

7.3.2.5 Fire. A fire starts. Roll 1D10 to determine its intensity.

1-5: Minor fire. The ship loses 2% of its absorbable damage points per intermediate turn until the fire is put out. Submarines must raise their snorkel to ventilate the ship, or surface if not fitted with a snorkel.

6-8: Major fire. The ship loses 4% of its absorbable damage points per intermediate turn. Surface ships must halt air operations, maneuver to put the wind 30° off either bow, and slow to 15 knots or less. If they do not maneuver or slow down, add +2 to the fire reduction/extinguishing roll.

Cargo Damage Table

Cargo	Die Roll	Result
Munitions	1-2	1D100% of the munitions are lost
	3-7	1D100% of the munitions are lost. Fire: add 1 to fire severity and to reduction/extinguishing rolls. There is a 25% chance of explosion each following intermediate turn
	8-10	Explosion. Nearby ships take DP based on the amount of munitions, in tons, in the hold. At 500 yds range, DP = tons/5. At 1,000 yds range, DP = tons/25. At 2,000 yds range, DP = tons/200

If a compartment's munitions explode, there is a 70% chance that each adjacent compartment's munitions also explode. Fires or explosion chances can be stopped by flooding the hold, but all cargo stored in that compartment will then be lost.

| Oil | — | Fire. Add 1 to the die roll determining its severity if it's crude oil. If refined products, add 2. If avgas (aviation fuel), add 3. Add the same number to the reduction/extinguishing roll | | Troops | 1-3 | DP = number of casualties | | | 4-6 | DP x 2 = number of casualties | | | 7-9 | DP x 3 = number of casualties | | | 10 | DP x 4 = number of casualties | | General supplies | — | DP/2 = tons destroyed | | Vehicles | — | DP/2 = vehicles destroyed | | Aircraft | — | DP/5 = aircraft damaged |

The ship is considered illuminated at night for purposes of visual detection and any fire directed at it. It will also illuminate or reveal the outlines of other ships in the same way a flare or star shell would. Submarines must surface.

9-10: Severe fire. The ship loses 6% of its absorbable damage points per intermediate turn. Surface ships must halt air operations, maneuver to put the wind 30° off either bow, and slow to 15 knots or less. If they do not maneuver or slow down, add +2 to the fire reduction/extinguishing roll.

The ship is considered illuminated at night for purposes of visual detection and any fire directed at it. It will also illuminate or reveal the outlines of other ships in the same way a flare or a star shell would. Submarines must surface.

Conflagration. A conflagration is defined by the US Navy as an out-of-control fire. If the percentage of the ship consumed reaches 15% or more of its absorbable damage points, the ship is ablaze. There is a 25% chance per intermediate turn (cumulative) that the ship's magazines explode, immediately sinking the ship. This can be avoided by ordering the magazines flooded during the planning phase of an intermediate or tactical turn. The ship will then lose all ammunition for its weapons and stored below-deck aircraft ordnance.

If the total percentage is not reduced below 15% by the next intermediate turn, the fire is out of control and the order is given to abandon ship. If the percentage is reduced below 15%, the conflagration danger is eliminated.

Damage Control: Reducing a Fire. For each fire, roll 1D10 during the planning phase of the next tactical turn and of each following intermediate turn: 1-4 means the fire has been reduced by one level (2%) or a minor fire has been put out; 5-8 means the fire continues as before; 9-0 means the fire's intensity increases by one level (2%). A severe fire cannot get worse.

7.3.2.5.1 Missile Fuel (optional rule). Every hit on a ship by an air-to-surface or surface-to-surface missile with a warhead of 20 kg or more, at 75% or less of its maximum range, can cause a fire critical hit (in addition to all other damage normally inflicted by the missile). An aircraft that crashes into a ship can also cause a fire critical hit.

Roll 1D10−3 for its severity. This critical hit is caused by unburned fuel spilling onto the impact site and being ignited by the explosion.

7.3.2.5.2 Assistance from Other Ships (optional rule). If a ship maneuvers within 100 yards of the damaged ship and follows an identical (parallel) course at the same speed, it can assist in fighting major and severe fires. Up to 2 ships can assist, one on each side. As long as the ship's speed is below 10 knots, there is no risk of collision.

Each ship assisting in firefighting lets the player subtract 1 from the reduction roll for a major or severe fire consuming its damaged vessel.

Ships themselves consumed by any type of fire, even minor, or damaged more than 50%, cannot assist other ships with firefighting.

7.3.2.6 Flight Deck. The ship's flight deck is hit by a strike that penetrates through to the hangar. Roll 1D6 for location: 1-2 means the hit occurs forward; 3-4 means the hit occurs amidships; 5-6 means the hit occurs aft. Roll (1D10 x 5) + 25 to determine what percentage of the aircraft on the flight deck is destroyed; roll the same way if aircraft are present in the hangar (see 7.3.2.1 for aircraft damage).

7.3.2.7 Flooding. A breach has been punched in the hull, letting water in. The compartment must be quickly isolated (sealed) or the ship will sink. Damage to other sections of the ship, or failure to seal off all accesses through which flooding can spread, can make this difficult. Many ships have been lost to progressive flooding from a single leak. For each flooding critical hit, roll 1D10 to determine its severity.

1-5: Minor flooding. The ship loses 2% of its absorbable damage points per intermediate turn until the flooding is isolated.

6-8: Major flooding. The ship loses 4% of its absorbable damage points per intermediate turn. Ships must slow to 15 knots or less.

9-10: Severe flooding. The ship loses 6% of its absorbable damage points per intermediate turn. Ships must slow to 15 knots or less.

For major and minor flooding, the submarine must reduce its depth to shallow.

Capsizing Risk. If the total percentage of flooded sections reaches 15% of the ship's absorbable damage points, there is a risk the ship capsizes (rolls over). It is not so much the total amount of water that has entered the ship, but the uncontrolled rate at which it is entering, that creates this capsizing risk.

The chances of this happening are 25% (cumulative) and must be checked by die roll during each intermediate turn until the flooding is isolated (compartmentalized) and the total flooding percentage drops below 15%.

Damage Control: Isolating Flooding. For each flooding critical hit, roll 1D10 during the planning phase of each intermediate turn: 1-4 means the flooding has decreased by one intensity level (2%) or minor flooding has been completely isolated; 5-8 means the flooding continues as before; 9-10 means the flooding has worsened by one intensity level (2%).

7.3.2.8 Hangar. A strike has directly hit the ship's hangar. Roll 1D10 x 5 + 25 to determine what percentage of aircraft in the hangar is destroyed (see 7.3.2.1).

7.3.2.9 Thick Hull. A breach has been opened in the submarine's thick (pressure) hull. This results in catastrophic flooding. If the submersible is at periscope or shallow depth during the tactical turn in which the hit occurs, it must perform an emergency surfacing and surface. The crew abandons ship while the submarine sinks like a surface ship (7.2.6). If the submarine's hull is breached at intermediate depth or deeper, it sinks immediately and automatically.

7.3.2.10 Rudder. The ship's rudder and steering gear are damaged. Maximum speed is reduced to 1/3 of its original value; the heading-change value is divided by 3 (a maximum 45° turn becomes 15°).

Submarines lose depth control (due to the loss of diving planes). A submerged submarine has a (5 x its speed in knots)% chance of accidentally changing depth. Roll before each planning phase. If it happens, roll 1D10 to determine how: 1-5, it rises one depth level; 6-0, it sinks one depth level. It cannot descend below its maximum depth level, and if this happens, it is crushed. If it rises one level from periscope depth, it will surface, but since it will have negative buoyancy, it will submerge again during the next tactical turn (unless the player loses depth control again next turn).

7.3.2.11 Detection System. One of the ship's remaining operational detection systems has been destroyed. Determine which one by random die roll. Submarine detection systems include periscopes (most submarines have 2). If there is no detection system aboard, or if they have all been destroyed, ignore this critical hit.

7.3.2.12 Sonar. An underwater detection system (sonar) has been damaged. Determine by random die roll which sonar, among those remaining, was destroyed. If the target has no sonar, or if they have all been destroyed, ignore this critical hit.

7.3.2.13 Mounted Weapon. One of the mounted weapons has been destroyed. Determine which one by random die roll. "Mounted weapons" include elevators, catapults, and anything listed in Annex A as a weapon for that ship.

Once the affected mounted weapon has been determined, roll 1D10. On 1-2, the weapon's fire director has been destroyed. If it has no fire director, or on a result of 3-10 (0 on the die), the mount is destroyed. If the mount has more than 4 tubes/guns/rails, they are not all destroyed. Roll 2D10 + 20 to determine what percentage of the tubes/guns/rails is destroyed.

If the mount has already been destroyed, ignore the critical hit. No additional damage occurs.

If the gun/launcher was hit, roll 1D10. The mount's ammunition detonates on a result of 9-0. The explosion of missiles or a magazine stored below deck will destroy the ship. The explosion of an exposed (external) torpedo tube, or a mounted missile (e.g. Mk 141 Harpoon), inflicts damage on the vessel equal to a warhead. Mounted guns with exposed ammunition stores do not inflict additional damage.

Armor Effects

Armor Value	Bomb Penetration Type	Gun (AP Shell) Penetration	Gun (HE Shell) Penetration	Missile Penetration
Light (L)	GP	76-120mm	76-130mm	Fragments (*)
Medium (M)	SAP	121-140mm	131-275mm	0-25 DPs
Heavy (H)	AP/HEAT	141-190mm	276-406mm	26-99 DPs
Special (S)	Special AP	191-406mm	—	100+ DPs

The armor penetration values for each gun in Annex C1 are given for short-range fire. At long range, reduce the armor value by one level. Consequently, a 203mm gun firing HE shells can penetrate medium armor at short range, but only light armor at long range.

() Air-burst shells of all calibers must be treated as fragments.*

Ammunition stored below deck can be flooded during the planning phase, which prevents a critical hit from detonating it.

See 7.3.2.1 for resolving aircraft destruction.

7.3.2.13.1 Effects on Weapons and Their Fire Directors (optional rule). To determine the location of a destroyed weapon or its destroyed fire director (which, for a ship, determines the remaining weapons' ability to be directed), roll randomly to select the destroyed mount. For example, a ship with 2 similar mounts, fore and aft, takes enough damage to lose one of the two. Roll 1D6: 1-3, the forward mount is destroyed; 4-6, the aft mount is destroyed. Players should know this slows the game down; die rolls should be kept secret from the opposing player until the remaining mount is used.

7.3.3 Armor Effects on Critical Hits. Armor can protect a ship's vital areas, which in Harpoon game terms means the chance of certain critical hits is reduced. The construction or refit of many ships includes an armor layer around vulnerable areas, such as magazines and electronics. A ship's remarks section shows whether it has critical-hit armor and, if so, its location and quality by a letter. For example, a Spruance has "critical hit armor: detection systems and Mk 143 ABL L." This means it has light (L) armor around its detection systems and its Mk 143 ABL mounted weapon.

Other ships, especially carriers, have armored decks and armor belts (vertical armor) that provide general protection to the entire ship. This armor does not just protect the ship's vital areas: until it is penetrated, damage inflicted on the entire ship is halved.

Damage is inflicted in 2 ways in Harpoon. First, critical (vital) equipment may be destroyed by critical hits, following which flotation damage is determined by tallying the number of damage points inflicted. Critical-hit armor is designed to protect a specific location or piece of valuable equipment. General armor protects most or all of the hull and reduces the weapon's overall impact. There is an interplay between the two, since reducing overall damage also reduces the number of critical hits.

If a ship takes damage and critical hits are inflicted on armored areas, the armor protecting that area must be penetrated, or the critical hit is ignored.

To determine whether a ship's general armor affects the damage it receives, for each weapon hitting the ship during the tactical turn it is damaged, check whether the weapon can penetrate its armor. If it cannot, halve the damage it inflicts on the ship.

Once the number of critical hits has been calculated, check whether the ship's affected areas are protected by an armor thickness. If so, check penetration capability against the armor value on the armor effects table, using the largest weapon hitting the ship that tactical turn.

Example: USS Spruance has critical-hit armor "Sensors & Mk 143 ABL L." It is attacked by a Sovremennyy-class destroyer, using its 130mm guns loaded with HE shells. The firing range is 7 nm, which is beyond half its range. It hits its target, inflicting 22 damage points (11 DP for each mount). After calculating the critical hit ratio and rolling for the number of critical hits, 2 critical hits are inflicted on the US destroyer. The first hits the engine room, the second the detection systems. Since the latter is armored, penetration must be checked. Looking up the armor value on the armor effects table, a 130mm gun firing HE shells at short range would penetrate light armor. However, the Sovremennyy is firing at long range, which reduces armor penetration by one level; the detection system's armor is therefore enough to protect it.

It is the responsibility of the hit ship's player to check and declare any protective armor at the appropriate time. Once damage is resolved and play has moved on, it is too late to modify or reduce the damage inflicted (someone will have left a hatch open).

7.4 Repairs

The effects of critical hits cannot be repaired during a battle, except for putting out fires and isolating flooding. Some damage, especially affecting detection systems and weapons, can be repaired afterward. Damage affecting the ship's structure (damage points) is generally not repairable, except in port. Some other damage (relating to flotation damage from flooding) can be eliminated by pumping the water out. Ships, however, do not carry structural repair facilities aboard.

To determine which systems can be repaired, take the ship's remaining total absorbable damage points and divide it by its original absorbable damage-point total. The resulting score is used for a repair roll. A 1D100 roll less than or equal to the repair score indicates the system has been repaired and is operational. For example, a ship with 37 remaining absorbable damage points out of an original 100 has a repair score of 37%. The repair roll is only used for certain critical hit types.

7.4.1 Mounted Weapons. Make repair rolls 6, 12, 24, and 48 hours after the battle ends. If a system is hit or damaged again before a repair roll succeeds, recalculate the score and start over. A failed 48-hour repair roll means that system cannot be repaired at sea.

7.4.2 Detection Systems. Make repair rolls 1, 12, 24, and 48 hours after the battle ends. If a system is hit or damaged again before a repair roll succeeds, recalculate the score and start over. A failed 48-hour repair roll means that system cannot be repaired at sea.

7.4.3 Flooding. Automatically remove half the damage points from flooding (sailors pump the water out), but there is a chance the seal fails. Submarines must remain at periscope depth, or the seal automatically fails. The chances of this happening for surface ships equal (sea state x that day's maximum speed in knots) in %.

Example: a ship with a flooding seal maintains a cruising speed of 15 knots in sea state 3. The chances the seal fails are (3 x 15)% = 45%. Had the ship cruised at 10 knots, the chances would have been (3 x 10)% = 30%. If the ship maintained 15 knots in sea state 6, the chances would rise to 90%. Reducing speed to 5 knots would bring the chances to 30%. The chances of losing the seal can never exceed 90%.

7.4.4 Fire. A fire can reignite 1 hour (10%), 12 hours (5%), 24 hours (1%), and 48 hours (1%) later. Determine the fire's size using 1D10−2 applied to section 7.3.2.5. Use this procedure for all fires (except aircraft fires). Aircraft fires cannot reignite.

7.4.5 Engine Room. Make repair rolls 1, 12, 24, and 48 hours after the battle ends. If a system is hit or damaged again before a repair roll succeeds, recalculate the score and start over. A failed 48-hour repair roll means that system cannot be repaired at sea.

7.4.6 Bridge/CIC. Make repair rolls 12, 24, and 48 hours after the battle ends. A fire on the bridge is resolved per rule 7.4.4. Degraded operations are automatically permitted 1 hour after the critical hit is taken. The takeoff/landing rate is halved. Normal operations are permitted once the repair roll succeeds.

7.4.7 Rudder. Make repair rolls 1, 12, 24, and 48 hours after the battle ends. If a system is hit or damaged again before a repair roll succeeds, recalculate the score and start over. A failed 48-hour repair roll means that system cannot be repaired at sea.

7.4.8 Flight Deck. Make repair rolls 12, 24, and 48 hours after the battle ends.

7.4.9 Aircraft. A destroyed aircraft has a 50% chance of only being damaged and repairable per rule 8.2.

7.4.10 Cargo. Cargo cannot be repaired.

7.4.11 Sonar. Make repair rolls 1, 12, 24, and 48 hours after the battle ends. If a system is hit or damaged again before a repair roll succeeds, recalculate the score and start over.

7.5 Equipment Availability (optional rule)

Just before starting the game (or daily in a campaign game), roll 1D100 for the propulsion plant, each detection system, and each weapon system on the ship. Western systems have a 2% chance of being down; Russian equipment has a 5% chance of being down. Third-world equipment has an 8 to 10% chance of being down.

These breakdowns can be repaired per the rules in section 7.4.

Those seeking additional detail for campaign play can also roll to randomly determine exactly when during the coming day the equipment will fail. Broken equipment cannot be repaired during tactical play. During non-battle periods, you can repair it as if it had suffered a critical hit against that equipment type, using the damage repair table. Systems that could not be repaired within 48 hours cannot be repaired at sea.

Damage Repair Table

Crew	Undamaged Ship	Damaged Ship
Western	80%	(remaining DP/absorbable DP) %
Soviet or 2nd-tier country	60%	(remaining DP/absorbable DP) % − 20
3rd-tier country	40%	(remaining DP/absorbable DP) % − 40

2nd-tier countries: Eastern Bloc nations, South Korea, Taiwan. 3rd-tier countries: all others.

The repair score can never be below 10% nor, under any circumstances, above 80%.

Chapter Eight – Aircraft Availability

Aircraft, like all machines, need maintenance to stay functional. Unlike automobiles, they cannot simply refuel and head back into combat. Sensitive electronics, carefully balanced turbine engines, and complex hydraulic systems all require maintenance, or they will fail in flight or perform below full capacity. These checks must be carried out in peacetime and in wartime.

An aircraft can only fly a limited number of missions per day. The limiting factors are pilot fatigue and the minimum maintenance needed to keep the aircraft airworthy, as well as the flight time needed to actually accomplish the mission. Although aircraft in Harpoon are assumed to function perfectly, they can be damaged in combat or suffer ordinary mechanical failure. The following optional rules can be used to track aircraft status throughout a campaign game's battles, to determine repair time, and what an aircraft needs to avoid mechanical failure.

They also cover pilot endurance and its limitations.

8.01 Definition: Turnaround Cycles. A turnaround cycle is the block of time during which maintenance and missions take place. Each day consists of 8 three-hour mission cycles.

Missions require at least one flight cycle and may last longer. Using the aircraft endurance rules, determine how many hours the aircraft will remain airborne. Divide this number by 3, rounding up, to get the number of cycles needed for the mission. For example, a mission involving 2 hours of flight will take one cycle. A mission involving 8 hours of flight will take 3 cycles.

An aircraft must undergo routine maintenance after 2 missions. Routine maintenance takes at least one cycle and may take longer. Divide the aircraft's number of flight cycles by 2 and round up. For example, if a mission involves a 3-cycle flight (e.g. a long-range reconnaissance mission), routine maintenance will need to take 2 cycles. Routine maintenance can only be done after the mission, and will then let the aircraft fly 2 consecutive missions without needing maintenance.

Routine maintenance must be performed on both damaged and functional aircraft.

Repairing a damaged aircraft may require several cycles. Corrective repair may take a variable number of cycles and is described in section 8.3.

Pilots must be briefed before and debriefed after each mission. Each of these requirements takes one cycle. However, debriefing for one mission and briefing for the next can take place in a single cycle.

8.1 Pilots and Flight Crew

Flight crews need rest, even in a combat environment. Skipping sleep to fly one more mission can result not only in the loss of the pilot, but also mission failure. Likewise, not every pilot can fly every mission. Leadership requires skill and experience, which makes some officers more valuable, and necessary, for the most important missions.

8.1.1 Crew Flight Scheduling. Aircraft and pilots may be assigned as you wish, as long as the following limits are not exceeded:

1. An aircraft cannot fly more than 4 missions per day, no more than 2 in a row. These must be followed by routine maintenance periods. Air missions lasting 3 cycles or more must be followed by one maintenance cycle.
2. Pilots can only fly a maximum of 3 missions per day. During all other cycles, they can only fly per the requirements of scheduling, briefing, and debriefing.
3. Division leader. Any mission involving 3 or more aircraft requires the squadron commander (CO), his executive officer (XO), or a division leader to be assigned to it.
4. Section leader. Any mission involving 2 or more aircraft requires the squadron commander (CO), his executive officer (XO), or a division leader to be assigned to it.

8.1.2 Squadron Structure. A typical squadron's flight personnel is described below. Although this model has some variation, it is roughly similar for every country with an air force. Form follows function.

Assuming a squadron made up of 12 aircraft:

• Squadron Commander (Lt Colonel/Commander)
• Squadron Executive Officer (Major/Lt Commander)
• Division Leader (2 per squadron) (Captain/Lieutenant USN)
• Section Leader (4 per squadron) (1st Lt/Lt j.g.)
• Operational Combat Pilot (4 per squadron) (2nd Lt/Ensign)

This lets 12 aircraft be flown.

Normally, a squadron will have more pilots than aircraft, with approximately 2 or 3 (1D6/2, rounded down) spare pilots available at the start of a conflict. For each additional pilot, roll 1D6: 1-3, operational combat pilot; 4-5, section leader; 6, division leader.

For two-seat or multi-seat aircraft, the number of co-pilots, navigators, flight engineers, or other flight personnel equals the number of additional pilots-in-command. Crews should normally stay intact unless they suffer combat losses.

The squadron executive officer (ops officer/XO) replaces the squadron commander if he is reported missing. Other squadron leadership positions can be filled by lower-ranked pilots with a roll of 1 on 1D6 for each candidate. This die may be rerolled once per day until the position is filled.

Several squadrons will form a wing, or, in Russia, a regiment. While aircraft types are fairly homogeneous within a squadron, they can vary greatly within a wing.

8.1.3 Crew Survival. Whenever an aircraft is destroyed, whether by direct fire or succumbing to damage taken during the battle or on the way home, the crew has a chance to eject or bail out. There is a 50% chance the flight crew successfully ejects from a destroyed aircraft.

Rescued crews can return to duty once their recovery time has been determined. Roll 1D100 on the following table:

01-25: must recover for 1D6+1 cycles 26-50: must recover for 1D6+1 days 51-75: must recover for 1D6+1 months 76-00: will never be cleared to fly again — a strike

8.1.4 Flight Crew Replacement. Each week, roll 1D6. On a result of 1, the squadron is assigned 1D6/3 (1 or 2) pilots. For each replacement pilot, roll 1D6: 1-3, operational combat pilot; 4-5, section leader; 6, division leader.

8.1.5 Aircraft Replacement. Each week, roll 1D6 on the following table:

Reduction in Aircraft Strength	Die Roll 1	2	3	4	5	6
1-2	—	—	—	—	—	1
3-4	—	—	—	—	1	2
5-6	—	—	—	1	2	3
7-8	—	—	1	1	2	4
More than 8	—	1	2	3	4	5

8.2 Aircraft Damage

Any damage inflicted on an aircraft during a Harpoon game is treated as enough to destroy it or force it to abort its mission. The aircraft is therefore removed from play, but its final condition must still be determined. This rule explains how to determine an aircraft's damage level.

8.2.1 Combat Damage. An aircraft that is hit in Harpoon is immediately removed from play. Afterward, whether during the game or after the engagement ends, roll 1D100 for each aircraft that was hit:

01-40: destroyed

41-50: critical damage: The aircraft suffered very severe damage. Crews take photos of aircraft in this state to show their buddies at other bases.

51-70: heavy damage: The aircraft suffered major structural damage.

71-00: light damage: The aircraft suffered damage to some components that make it unfit to fly.

If a damaged aircraft must fly more than 150 nm to reach a "friendly" landing site, the player must roll 1D100 again: if the roll is above the score, it makes it home; if the roll is at or below the score, it crashes.

Critical: 75% Heavy: 50% Light: 25%

At the referee's discretion, the enemy player may or may not know precisely how many hit aircraft were actually destroyed, or how many damaged (enemy) aircraft survived and made it back to base.

8.2.2 Operational Damage. As a result of normal wear and tear, an aircraft may suffer a component failure. An equipment failure is commonly called a "gripe." A technical failure serious enough to ground an aircraft is a "downing gripe."

Although in real life such failures can occur in flight, thereby affecting an aircraft's ability to complete its mission, most can be overcome, and rules for resolving failures based on the type of equipment involved would be too complex to formalize and would hurt the game's flow. Instead, every time an aircraft returns from a mission, roll 1D100:

Aircraft Operational Damage Table

Event	1st-Tier Country	2nd-Tier Country
Heavy damage	01-02	01-04
Light damage	03-08	05-15
No "gripes"	09-00	16-00

The chances of a "gripe" occurring depend on the aircraft's maintenance level. This depends on the training quality of the maintenance personnel, spare parts availability, repair organization, etc. Typical 1st-tier countries include the USA, Russia, or France. Typical 2nd-tier countries include Libya or Vietnam. There are many ways to rank them, but these 2 levels roughly represent the main difference in maintenance capability.

8.3 Aircraft Maintenance

Two different aircraft maintenance systems are presented here. One is abstract and can be used to manage a large number of aircraft under strain. The other is more detailed, but gives the player more flexibility in repairing the most important aircraft.

8.3.1 Aircraft Maintenance (simplified rules). At midnight, roll 1D100 for each damaged aircraft on the abstract aircraft repair table below.

Abstract Aircraft Repair Table

Chances of repair

Damage Level	1st-Tier Country	2nd-Tier Country
Critical damage	35%	15%
Heavy damage	60%	40%
Light damage	85%	65%

8.3.2 Aircraft Maintenance (detailed rules). Maintenance teams are used for aircraft repair and routine maintenance work. Each cycle, a maintenance team can either spend its entire time repairing a single aircraft, or perform routine maintenance on up to 3 aircraft. Both damaged and functional aircraft must undergo routine maintenance.

Teams can combine their efforts to repair a damaged aircraft. If it takes 12 cycles to repair a heavily damaged aircraft, 4 teams can do it in 3 cycles. To simplify bookkeeping, after a maintenance team spends one cycle working on the damaged aircraft, reduce the number of cycles remaining by one. Once the aircraft has been worked on for the required number of cycles, it is repaired.

A squadron has 8 maintenance teams. Each maintenance team can only be used for 4 cycles per day. They may be used during any cycle. Several teams may work simultaneously on the same aircraft. A complete repair requires the following number of cycles:

Light damage = 2 cycles Heavy damage = 1D6 + 3 cycles Critical damage = 1D6 + 10 cycles

Example: it should only take one cycle for 3 maintenance teams to repair a lightly damaged aircraft and carry out its routine maintenance.

Critical Hit Types (continued)

Roll	Submarines (all weapons)	Torpedoes vs. Surface Ships	Air Bursts/Fragmentation
1	Mounted weapon	Mounted weapon	Detection system
2	Thick hull	Flooding	Detection system
3	Detection system	Flooding	Detection system
4	Flooding	Flooding	Mounted weapon
5	Flooding	Flooding	Mounted weapon
6	Flooding	Sonar	Weapon/flight deck
7	Fire	Engine room	Weapon/flight deck
8	Engine room	Engine room	Weapon/flight deck
9	Bridge/CIC	Engine room	Flight deck
10	Rudder	Rudder	Bridge/CIC