While I agree that hovering IMAC planes are a potential safety threat, my observation of an experienced pilot with a sudden gust of wind tossing the plane toward the flight line, is that most will simply chop the throttle and suffer damage to their plane instead of hitting people in the pits. I recall a jet going through the roof of a house at one of the Top Gun scale events. Don't know how much damage a Heli would afflict, they are usually going fairly slow when they crash, and the blades seem t break fairly easily.