[thruster]

ok, this is a gamey bit i dnt like.
IRL your flak crew are not imbeciles and will shoot at the most threatening in-range aircraft when ordered to. As captn, you would simply tell them to open fire. targetting via your binos is silly.

there has to be an order/setting [perhaps with the WO] that effects accurate flak fire on the closest target. oh, and a cease fire order too.

Edit: unless of course YOU want to man the flak gun.