A special type of combat by AA guns. It occurs before normal combat, and only aircraft can be hit. Only 1 AA Gun can fire even if multiple guns are present.
In AAC, AA guns could fire in both combat and non-combat movement (as well as combat)and the attacker could choose which type of plane is shot down. In AAR, AA fire was only allowed in combat and combat movement, and losses were rolled separately for each plane type. In AA50, AA fire during movement was dropped entirely.