Can we maybe have choppers on a timer rather than having them take off only if someone is in there? For example, let it lift off after a min(just tossed out a number) when it lands each time. That way, it keeps people guessing. Is there someone in there? Or is it just doing its run? If I am not mistaken, that is how it was in BHD?
Also, a small cosmetic suggestion. What about tossing in a couple invulnerable bots or something in the seats? Just to make it a bit more real than a chopper flying on it's own.