Currently, the UAV's ATGM can only be launched as the flight controller, since the pilot cannot move his view around, he can only lock onto targets right in front of his view. This means, if the UAV/operator wants to destroy an enemy target, he must shift away from his current waypoint and go on a strafing run in the direction of the target, to lock onto it. Which is pretty inefficient since UAVs usually loiter around targets.
My suggestion is that the ATGM will be accessed when controlling the turret, and it could be locked on whatever the optical turret is aiming at - 360 degrees, as long as it's not airborne.
The ATGM should also track the turret's aim when it's not locked onto anything, to simulate it homing onto the turret's laser or like in SACLOS missiles.
An alternative option is providing the turret operator with a "Command fire" option similar to the ULBs from ArmA 2 have. The missile would be launched at the turret's laser if it's activated, or at a tab lock target.(Which could be a vehicle or a laser target from another source.)
Also, see my ticket about adding stabilization to the turret, which would be necessary if using my alternative option(using the UAV's own laser): http://feedback.arma3.com/view.php?id=12853