Well, the difficult part seems to be to keep the chopper pilot busy during game play. It wont be very much fun to play the pilot if his objectives can be sumarized as insertion/extraction. You need some sort of objective for the chopper pilot while the grunts are caught in the crossfire at ground level.
A recon assignment, or an extraction of AI-troops that takes place simultaneously as the rest of the mission is one idea. Maybe a distresscall from a AI-team in the middle of the fighting.