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Air Combat Maneuvering (ACM)

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Evasive action

Air Combat Maneuvering is the art of maneuvering a combat aircraft in order to attain a position from which an attack can be made on another aircraft. It relies on offensive and defensive basic fighter maneuvers (BFM) in order to gain an advantage over an aerial opponent. It is advised that you read the article on Energy before moving on to this topic.

Basic Fighter Maneuvers (Concepts)Edit

Once an attacker gets behind a defender, there are three problems to solve in order to prosecute the kill. The attacker must be able to get into the same geometric plane as the defender, get in range without overshooting, and be able to lead the target. The defender will usually turn aggressively to spoil the attacker's solution.

Turn CircleEdit

Turn circle geometry

Turn circle geometry

Aircraft turn in circular motions, following a circumference around a central point. The circumference is often referred to as the "bubble," while the central point is often called the "post." Any change in the g-force load on the aircraft causes a change in the bubble's size as well as a change in turn radius, moving the post in relation to the fighter. Because an aircraft turning at its maximum load cannot turn any tighter, any aircraft located between such a fighter and its post is momentarily safe from attack. It is in this area where an attacking fighter will usually try to position itself. Once inside the defender's bubble, the attacker will be in lead pursuit and may have an opportunity for a lucky "snapshot" hit. If the attacker can maneuver onto the defender's flight path before an overshoot occurs, the attacker will be able to stop or reverse closure rate. The most desirable position is, following the defender's flight path, a distance equal to one turn radius behind the opponent. This position, from which the attacker will be able to safely maintain command of the fight, is termed the "control point." The control point lies in the heart of an imaginary, cone-shaped area, called the "control zone," and it is within this zone that the attacker will have both sufficient time and range to react to the defender's countermeasures.


During a dogfight, the term "overshoot" refers to situations in which the attacker either crosses the enemy's flightpath or passes the defender, ending up in front. Passing the defender is referred to as a "wingline overshoot". Also called a "3-9 line overshoot" or a "dangerous overshoot," this occurs when an attacking aircraft approaches too fast and accidentally crosses the defender's wingline, (an imaginary line passing through the center of the aircraft at the 3 o-clock and 9 o-clock positions). A wingline overshoot is usually referred to as "flying out in front" and causes "role reversal," putting the attacker in range of the defender's weapons, and the attacker suddenly becomes the defender. When the attacker crosses the defender's flightpath, the situation is called a "flightpath overshoot." This happens when an attacker fails to control closure and crosses the defender's flightpath from behind. Although not necessarily dangerous, it is possible for a flightpath overshoot to cause the attacker to fly out in front of the defender. More often, however, it greatly reduces the attacker's angular advantage over the defender. Flightpath overshoots are divided into two categories, called "control-zone overshoots" and "in-close overshoots." A "control-zone overshoot" occurs when the attacker crosses the defender's flightpath from behind the front edge of the control zone. After a control-zone overshoot, the defender will continue turning in the same direction to retain the acquired angular advantage, trying to prevent the attacker from getting a good aim. An '"in-close overshoot" happens when the attacker overshoots the defender's flightpath ahead of the control zone. This gives the defender the opportunity to reverse the turn and possibly to cause a wingline overshoot, allowing the defender to move in behind the attacker and reverse their roles. 

Circle FlowEdit

Circle flow Aircraft can turn either towards or away from each other. How the opponent turns in relation to the other determines the flow of the fight. If two fighters meet head-on, they will usually make a very close, neutral pass, called a "merge". After the pass, both fighters may turn to engage. If the two fighters turn in the same direction, (i.e.: both turn to the north), they will be traveling toward each other along the same turn circle. This type of engagement is known as "one-circle flow". If the aircraft turn in opposite directions, (i.e.: one turns north but the other turns south), they will move away from each other, flying around to engage each other on separate turn circles. This is called "two-circle flow." One-circle flow will result in another merge, unless an angular advantage can be obtained. During one-circle flow, the fighter with the smaller turn radius will have the advantage. Pilots will often pitch-up out-of-plane while increasing thrust, to help minimize turn radius. Because it does not really matter where the two fighters meet in the circle, turn rate is of little importance during one circle flow. Therefore, it is often called a radius fight. An out-of-plane maneuver, such as a displacement roll, is a viable option for reducing turn radius. Two-circle flow will also result in another merge. In two-circle flow, turn radius is of little importance, because what matters is which fighter can get back to the merging place first. Two-circle flow is a turn rate fight, and the angular advantage usually goes to the aircraft with the higher turn rate at its corner speed. Pilots will often slice turn in order to maximize their turn rate. A third option is called vertical flow, in which one or both fighters turn toward the vertical plane. If both fighters go up or down, the fight becomes one-circle flow. If one fighter goes up or down, while the other turns horizontally, it is really a modified version of one-circle flow. However, if one fighter goes up while the other goes down, it becomes two-circle flow. In both types of flow, the closest possible merge is desirable to keep the enemy at an angular disadvantage. Although circle flow is often described using neutral merges, the concept applies anytime two aircraft maneuver in relation to each other and the horizon. For instance, the "flat scissors" is an example of one-circle flow, while the "rolling scissors" is an example of two-circle flow.

Basic Fighter Maneuvers (Techniques)Edit

Combat SpreadEdit

The combat spread is hardest most basic of maneuvers used prior to engagement. A pair of attacking aircraft will separate, often by a distance of one mile horizontal by 1500 feet vertical. The fighter with the lower altitude becomes the defender, while the wingman flies above in "the perch" position. The defender will then attempt to lure their opponents into a good position to be attacked by the wingman. 

Defensive SplitEdit

A pair of fighters encountering one or two attackers will often use a defensive split. The maneuver consists of both defenders making turns in opposite directions, forcing the attackers to follow only one aircraft. This allows the other defender to circle around, and maneuver behind the attackers. Split s Spotting an attacker approaching from behind, the defender will usually break. The maneuver consists of turning sharply across the attacker's flight path, to increase AOT (angle off tail). The defender is exposed to the attacker's guns for only a brief instant (snapshot). The maneuver works well because the slower moving defender has a smaller turn radius and bigger angular velocity, and a target with a high crossing speed (where the bearing to the target is changing rapidly) is very difficult to shoot. This can also help to force the attacker to overshoot, which may not be true had the turn been made away from the attacker's flight path.

Barrel Roll AttackEdit

Barrel roll diagram-wiki

Barrel roll attack

The counter to a break is often a displacement roll called a barrel roll attack. A barrel roll consists of performing a roll and a loop, completing both at the same time. The result is a helical roll around a straight flight path. The barrel roll attack uses a much tighter loop than the roll, completing a full loop while only executing 3/4 of a roll. The result is a virtual 90 degree turn, using all three dimensions, in the direction opposite of the roll. Rolling away from the defender's break, the attacker completes the roll with the aircraft's nose pointed in the direction of the defender's travel.


An Immelmann trades airspeed for altitude during a 180 degree change in direction. The aircraft performs the first half of a loop, and when completely inverted, rolls to the upright position. The Immelmann is a good offensive maneuver for setting up a high-side guns pass against a lower altitude, slow moving opponent, going in an opposite direction. However, an Immelmann is a poor defensive maneuver, turning the defender into a slow moving target.

Split SEdit

The opposite of an Immelmann is the Split-S. This maneuver consists of rolling inverted and pulling back on the stick, diving the aircraft into a half loop, which changes the aircraft's direction 180 degrees. The split-s is rarely a viable option in combat as it depletes kinetic energy in a turn and potential energy in a dive. It is most often used to set up a high-side guns pass against a lower but fast moving opponent that is traveling in the opposite direction. Also, the split-s is sometimes used as a disengagement tactic. Real fighter pilots typically use the Split S when engaging a bogey at a lower altitude because the body tolerates positive G's better than negative ones.


A pitchback, also called a Chandelle, is an Immelmann that is executed in some plane other than the vertical. Basically just a pitch turn, the fighter will be at some angle of bank before performing the half loop and roll. Unlike the Immelmann, a pitchback depletes less kinetic energy and is harder for an adversary to track.

Low Yo-YoEdit

The low Yo-Yo is one of the most useful maneuvers, which sacrifices altitude for an instantaneous increase in speed. This maneuver is accomplished by rolling with the nose low into the turn, and dropping into a steeper slice turn. By utilizing some energy that was stored in the vertical plane, the attacker can quickly decrease range and improve the angle of the attack, literally cutting the corner on the opponent's turn. The pilot then pulls back on the stick, climbing back to the defender's height. This helps slow the aircraft and prevents an overshoot, while placing the energy back into altitude. A defender spotting this maneuver may try to take advantage of the increase in AOT by tightening the turn in order to force an overshoot. The low Yo-Yo is often followed by a high Yo-Yo, to help prevent an overshoot, or several small low Yo-Yos can be used instead of one large maneuver.

High Yo-YoEdit

The high Yo-Yo is a very effective maneuver, and very difficult to counter. The maneuver is used to slow the approach of a fast moving attacker while conserving the airspeed energy. The maneuver is performed by reducing the angle at which the aircraft is banking during a turn, and pulling back on the stick, bringing the fighter up into a new plane of travel. The attacker then rolls into a steeper pitch turn, climbing above the defender. The trade-off between airspeed and altitude provides the fighter with a burst of increased maneuverability. This allows the attacker to make a smaller turn, correcting an overshoot, and to pull in behind the defender. Then, by returning to the defenders plane, the attacker restores the lost speed while maintaining energy.

Lag Displacement RollEdit

A lag displacement roll, also called a "lag roll", is a maneuver used to reduce the angle off tail by bringing the attacker from lead pursuit to pure, or even lag pursuit. The maneuver is performed by rolling up and away from the turn, then, when the aircraft's lift vector is aligned with the defender, pulling back on the stick, bringing the fighter back into the turn. This maneuver helps prevent an overshoot caused by the high AOT of lead pursuit, and can also be used to increase the distance between aircraft.

High Yo-Yo DefenseEdit

To prevent an overshoot, an attacker in lead pursuit may need to correct with an out-of-plane maneuver. If the lateral separation is excessively high, the attacker will probably use a displacement roll. However, if the lateral separation is low enough, the attacker will likely use a high Yo-Yo. The high Yo-Yo defense can be a good tactic in these situations. The maneuver is performed when the attacker rolls away from the turn to begin the correction. The defender will begin to relax the turn by easing off of the stick, called "unloading", which causes both turn radius and speed to increase, restoring the fighter's lost energy. If the defender maintains the same angle of bank, the subtle maneuver will be very difficult for the attacker to spot. When the attacker completes the out-of-plane maneuver, the defending fighter has regained some of its energy. This allows the defender to, once again, turn harder into the attack, regaining an angular advantage over the higher energy attacker. If the attacker is surprised by the maneuver, a high Yo-Yo defense might even cause an overshoot.


The scissors are a series of turn reversals and flightpath overshoots intended to slow the relative forward motion (downrange travel) of the aircraft in an attempt to either force a dangerous overshoot, on the part of the defender, or prevent a dangerous overshoot on the attacker's part. The defender's goal is to stay out of phase with the attacker, trying to prevent a guns solution, while the attacker tries to get in phase with the defender. The advantage usually goes to the more maneuverable aircraft. There are two types of scissor maneuvers, called flat scissors and rolling scissors.

Flat ScissorsEdit

Flat scissors, also called horizontal scissors, usually occur after a low speed overshoot in a horizontal direction. The defender reverses the turn, attempting to force the attacker to fly out in front and to spoil aim. The attacker then reverses, trying to remain behind the defender, and the two aircraft begin a weaving flight pattern.

Rolling ScissorsEdit

Rolling scissors, also called vertical scissors, tend to happen after a high speed overshoot from above. The defender reverses into a vertical climb and into a barrel roll over the top, forcing the attacker to attempt to follow. The advantage lies in the aircraft that can pull its nose through the top or bottom of the turn faster. In battles with aircraft that have a thrust-to-weight ratio of less than one the aircraft will quickly lose altitude, and crashing into the ground becomes a possibility.

Defensive SpiralEdit

A defender that fails to outmaneuver the attacker can quickly become "out of airspeed and ideas". The defensive spiral is a maneuver used by the defender when the kinetic energy becomes depleted and other last-ditch maneuvers can not successfully be implemented. The maneuver consists of dropping the nose low during the turn and going into a spiral dive, using gravity to supply the energy needed to continue evasive action. The defensive spiral becomes a rolling scissors performed straight down. The defender's goal is to stay out of phase with the attacker until the ground is dangerously close. The advantage usually goes to the aircraft that can decelerate quicker, and the defender will often cut the power and extend the speedbrakes in an effort to force an overshoot. If this attempt is unsuccessful, the defender will usually pull out of the dive at the last possible second, hoping to cause the attacker to crash into the ground.


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