The Buzzard's missile lock is more trouble than it's worth; I just lost three kills in a row because of it. Had a bus full of players dead to rights with my dumbfire missile, but then the damn thing decided to lock on to a cop car two blocks over instead. It's also a pain in the ass during missions, since it almost invariably results in your missile tracking straight into the ground if your target's moving away from you at a decent speed. It'd be MUCH easier to simply lead your target, rather than being forced to fly almost perpendicular to your target and hope your rocket doesn't smash into the ground.
So is there any way to toggle aircraft missile lock? Or disable it completely?