The rule at our field is 50' from the flight line, and of course the planks have no problem keeping that distance, but the choppers do not comply, as was said on another post as they like to stay close to see their chopper. So is a safety rule that the choppers will not comply with really worth trying to inforce on them, as the planks wait untill their flight is over any way, and the only one they are indangering is themselves & other heli guys when they crash and the chopper beats it self to death as parts fly every where. In fact the plank guys wager if a chopper will crash or not.