My tests were done at "veteran" difficulty
1.Place an AH-99 Blackfoot, player as pilot, flying
2.Place an enemy Mi-48 Kajman, flying, at 1-2 km distance from player, facing away from the player
3.Set the behaviour to "COMBAT" for the enemy helicopter (by script or by waypoint)
3.Switch to manual fire, try to engage the chopper
Observed: enemy successfully decoys the missiles every time
Expected: when shot at 1-1.5km (basically, point blank) it should be impossible to react.