Couldn't have been somewhere in Essex could it?. A long standing debate on this issue and for many who participate in this action joining up isn't an option. Rather like paintball and other combat games military style flying is just another angle to the sport like aerobatics. Where this becomes less benign is where it inconveniences others or causes danger through non standard operating. What is the answer?. Don't know. Would I like the opportunity to play in a JP, L39, or even Yak 52 in this way? - Yes but I guess I would have to ensure that it wasn't likely to endanger others.