AA is invulnerable while at HQ

When the AA is camping in enemy spawn - your heli gunner locking missiles (or any locking missiles) WONT hit the AA, because the turret at spawn destroys it before it connects. Really annoying.

The AA is way to strong as it is, but being invulnerable at the own HQ is the icing on the cake. 

The AA needs balancing, maybe disabling locking mechanism of the AA if still at spawn/HQ would solve the issue and force the player to leave the HQ, hence balancing (but still overpowered) AA.