AV-8B Harrier II

The AV-8B Harrier Jump Jet appears in Call of Duty 4: Modern Warfare and Call of Duty: Modern Warfare 2. The Harrier is used by the Royal Navy and USMC to support their amphibious landing operations. They usually carry out Airstrikes against enemy fortifications and units in support of friendlies. As a VTOL aircraft, it is capable of hovering in place like a helicopter, though it mostly relies on its speed to avoid enemy fire.

It should be noted that the "hover in place" and engage troops like the Harrier does in the game series is a completely ineffective way of using the fighter. Fuel would be expended at a ridiculous rate, and it would be completely vulnerable to AA fire, not to mention other fighters.

Call of Duty 4: Modern Warfare
A flight of USMC AV-8B Harrier IIs appear in the mission Heat, callsign Falcon One. They provide close air support to the S.A.S. team using cluster bombs. Additionally the player can see USMC Harriers bombing targets in the mission Shock and Awe ahead of the Marine assault, thereby reducing resistance to a ground assault by the Marines. Two of the jets fly right over the player's position in the mission Charlie Don't Surf when they are on the roof of the TV station.

Call of Duty: Modern Warfare 2
The Harrier II also makes a handful of appearances in Campaign, though they are seen far less often than in Call of Duty 4, with the F-15E Strike Eagle replacing them in the role of Close-Air Support. In the level Exodus, prior to reaching the HVI's house, a pair of Harriers can be seen using their VTOL capability to take off from a driving range near the C-130 crash site.

The Harrier strike is an unlockable killstreak reward in Call of Duty: Modern Warfare 2. Requiring a killstreak of 7 (6 with the Hardline perk), the Harrier Airstrike calls in three Harrier jets: two to bomb the target location, and the third hovers in place over the selected area, and will attempt to kill enemy targets with its undermounted gun. The third jet will also fire missiles at an enemy Attack Helicopter, Pave Lows, or Chopper Gunner if seen in the air and will destroy them.

The Harrier Strike is an inaccurate representation of the AV-8B's abilities. Harriers are not designed to use their vector thrust nozzles to hover over an area for extended periods of time, only for take off and landing. While hovering, the Harrier uses immense amounts of fuel, overheats the engines and is very difficult to maneuver. Nonetheless, this hover mode is the main attack method used in multiplayer, where it can easily suppress large areas of the map. Also, real Harriers are not fitted with turreted machine guns, instead they are usually fitted with forward fixed 20mm or 25mm gun pods.

Unlike a Pave Low Helicopter, Harrier kills from the Airstrike extend the user's killstreak. This makes the Harrier very useful for achieving higher ranked killstreaks such as Chopper Gunner or AC-130. Because of the lengthy duration of the Harrier killstreak, players will often use it in conjunction with another killstreak to gain quick access to the Tactical Nuke killstreak reward. With the Stimulus Package patch, Pave Lows will also extend the killstreak, allowing for a particularly effective combination of a Harrier Strike and Pave Low to rapidly get kills.

Harrier compared to Attack Helicopter

 * The Harrier has to rotate towards the direction of its intended target before firing, giving players a warning if they're about to be targeted, and players can also 'circle strafe' a Harrier by staying underneath it and move around every time the Harrier starts rotating. The Attack Helicopter can seemingly attack enemies from all directions because of its rotating gun.
 * Harriers target enemies that it is facing regardless or often the nearest player. Helicopters are more selective and intelligent in picking targets and tend to attack the more dangerous players or those who attempt to shoot it down. Both can be avoided with Cold-Blooded, but if the aircraft targets a nearby teammate without Cold-Blooded, it could wound or kill you while trying to kill your teammate.
 * The hovering Harrier arrives and strikes within 4 seconds of calling it in, the helicopter takes about 15 seconds to arrive.
 * Harriers will hover making them an easier target, they will slightly move, but it is not much, helicopters will move around to get a better view of enemies and sometimes avoid players trying to take it out with rockets.
 * Harriers can shoot down helicopters while the Attack Helicopter can't attack air targets.
 * The Harrier remains in the air for 45 seconds after coming to a complete stop; the Attack Helicopter stays around for one minute upon reaching the battlefield.
 * Harriers can be devastating if deployed in the right place. However, it's more likely to get shot down straight away due to its high profile and relatively stationary position. Helicopters circle the map and have a lower profile.
 * Harriers have an airstrike component which drops two cluster bombs, followed by the hovering attack jet.
 * Harriers can sometimes be confused with the Airstrike by their similar function and appearance on the radar, Helicopters are easily exploited by their thin line on radar.
 * Harriers have an Airstrike, that can kill numerous players, an Attack Helicopter can target only one player at a time. (If they are in groups, they may be all killed at once)
 * Up to three Harriers can be in the airspace at the same time (doesn't matter if enemy or friendly). Helicopters can only be called in as long as no other helicopters are in the air (Care Package Little Birds don't count).
 * Harriers can't attack each other if there are two of the opposite teams. Attack Helicopters will stop enemy players from calling in a helicopter of their own as long as it remains in the field.
 * Harriers are considered more deadly as they kill players quicker with their short, controlled, powerful bursts of fire while players can escape a Helicopter shooting at them by running indoors.
 * Neither aircraft has flares, but the Harrier moves around less, making for an easy shoot-down. The Attack Helicopter moves around buildings so it can be harder to lock-on.
 * You get more points for destroying a Harrier than a Helicopter.
 * The Harrier's jets make a louder noise, announcing its presence on the field, even if a Counter-UAV is online, its guns make a quick noise that it is firing. The Attack Helicopter has little noise when flying, but it has to fire in longer bursts alerting players when it is targeting someone.
 * Calling in a Harrier requires you to mark an area on the map, and you are vulnerable to enemy fire during this process. Marking an area with lots of enemies can greatly increase the Harrier's effectiveness; conversely, marking an area devoid of enemies can greatly reduce the effectiveness of the Harrier. Managing to mark the ideal area without the aid of a UAV is usually difficult. The Helicopter does not require the player to mark an area, you flip a switch and it does its job, making it easier to use than the Harrier.
 * You can easily avoid the Harrier on small maps, as standing directly below it and moving around underneath it will stop it from targeting you.
 * It takes longer to eliminate a Harrier with LMG rounds, up to two clips from an RPD (Without Stopping Power Pro) Both aircraft can be eliminated by two RPG's and a single Stinger or Javelin.
 * You can block bullets from both aircraft by a Riot Shield, but the Helicopter will often move around to get a shot at your vulnerable point.

Trivia

 * When the Airstrike is in effect the first two Harriers making the Airstrike are smaller than the hovering Harrier attacking the other players.
 * Harrier jets do not collide with buildings.
 * The Harrier makes two references to the movie True Lies: when the player gets the game-winning kill, they receive the title "True Liar", and the prestige challenge for getting Harrier kills is called "You're fired!", a reference to the line Arnold Schwarzenegger says to the head terrorist before killing him.
 * In MP, a player using the Riot Shield can look at a diagonal angle to trick a Harrier into focusing all of its firepower on that single person. The user also gets +50 EXP from every burst from the Harrier. (+500 in S&D). This can continue even after the round has ended.
 * If the player gets kills with the Airstrike portion of the Harrier strike, they count as airstrike kills, like those of the Precision Airstrike and Stealth Bomber. These kills are recognized by the picture of three planes on the killfeed.
 * Harriers deployed by the Rangers, Task Force 141, and SEALs appear in their typical gray/silver colors. Harriers deployed by the OpFor, Militia, and Spetsnaz appear black, as do most of their killstreak aircraft.
 * It is possible to shoot down two Harriers with one stinger missile if the Harriers are close enough.
 * It is not recommended to use a helicopter-based killstreak, such as a Pave Low or Chopper Gunner, while an enemy Harrier is in the air because it will be shot down very quickly by the Harrier's missiles.
 * Harriers are most commonly used with the killstreaks Chopper Gunner or AC130 to get a Tactical Nuke.
 * Harriers have a very small role in the single player campaign.
 * When firing a Stinger Missile at a Harrier, be sure to aim as far away from the turret as possible. The reason for this is that the Stinger Missile will pass straight through the Harrier's turret, and not circle back or explode.
 * The laptop the player takes out to use the Harrier Airstrike is actually used by Rangers in the Modern Warfare 2 single-player mission "Of Their Own Accord" if you are observant enough.
 * If a Harrier shoots down an enemy Attack Helicopter, Pave Low, or Chopper Gunner, the player will not be awarded the Flyswatter challenge.
 * Amusingly it is possible to destroy a Harrier with a throwing knife, though it has to be damaged significantly before the knife is thrown. The following link showcases this, http://www.youtube.com/watch?v=x1tw4c0mHOg&feature=channel
 * As the Harrier cannot attack Cold Blooded users, one can presume they rely on Thermal Optics to spot enemies. This can explain how the Harrier can shoot players who are standing inside windows or doorways, as the Harrier pilot would have to be extremely skilled.
 * Sometimes when there is a Pavelow or an Attack Helicopter in the map already, and one person on the opposing team calls in a Harrier, if the Pavelow or Helicopter is in the way of the Harrier Strike or the last Harrier, then the Harrier will collide with the chopper, destroying it without using its weapons. The Harrier on the other hand will not be destroyed.
 * Be careful about calling in killstrikes that have flares with a harrier in the air, if it is targeted with the killstreak reward close enough it wont deploy flares but the harriers explosion will destroy it