We train on Tuesday nights at our club--closed to everyone except students. We take them out on the runway and stand behind their planes the first couple of times. Never had a problem with it and don't do it with more than one or two planes in the air. Everyone is on buddy box. After taking off, we grab 'em by the arm and walk them back behind the safety line--works great. We have had ocassions when, on other than training nights, someone wants to stand behind the plane for take off. Always ask permission and let others know what you are doing. Not had a problem with that either. Common sense and courtesy go a long way.