Or any decepticons, for that matter (i.e. TFP, though I do respect Prime Megatron for being enough of a boss to say screw Earth modes, I'm a cybertronian spacecraft). If they could fly in robot mode, why bother? What purpose did they have to hide their existence from the humans? More importantly, why would they fly together in swarms with some in alt mode and some remaining to appear as the giant robots they are? Doesn't that just limit their maneuverability during airborne combat?