An Anti-Air Missile or Surface-to-Air Missile (SAM) is a guided weapon designed to primarily engage enemy aircraft. Many kinds of anti-air missiles can only be used against aircraft, requiring an active weapon lock in order to launch the missile.
The SAAW 86 Anti-Air is available to Engineers as an unlockable weapon that deals direct damage. It is very effective against air vehicles and close-range infantry, but has little effect on ground vehicles and no splash damage against distant infantry.
Gunners in battlewalkers and Rorsch Kz-27 operators can use anti-air missiles that only release EMP. As with other EMP weapons, these can disrupt vehicles, impair vision, and deactivate Active Defense.
Anti-air missiles are just like their BF2 counterparts.
— Battlelog description
Anti-Air Missile is a vehicle specialization available for AA vehicles and mobile artillery in Battlefield 3. When equipped it acts as a secondary weapon, with a targeting reticle similar to that of Heat Seekers that allows the driver to lock onto and engage enemy aerial vehicles with two heatseeking missiles. American vehicles use FIM-92 Stingers, while Russian vehicles use SA-18 Igla missiles.
Anti-Air Missiles make an excellent complement for the AA vehicle's gun, being able to menace jets and helicopters at ranges where the primary gun is simply too inaccurate at to be useful. The missiles are also extremely useful on mobile artillery as well, allowing a user to effectively eliminate ground targets as well as protect itself from possible airborne enemies. The gunner seats on light anti-air vehicles (the HMMWV ASRAD and Vodnik AA in Endgame) have these as their default secondary weapon.
AA missiles can be deterred with IR Flares and ECM Jammer, and lock-on time slowed by Stealth. If the target vehicle has already deployed flares or ECM and you manage to obtain a lock-on, the twin missiles are almost a guaranteed kill; as such they are almost universally used. Each missile reloads independently, eight seconds after the previous one was fired.