The problem of safety is amplified when you have large crowds of people such as at airshows.
The crowds cover more area so there is a greater chance the plane will hit someone. The best
safety feature I can think of (especially for large airshows) would be a chain linked fence that
people would have to stand behind and that would also extend diagonally above thier heads. This
in addition to the requirement that the the engine MUST be programmed to shut down in failsafe
would make these events 90% safer. Of course people would still have to leave the fenced off area
to get food or go to the rest room...etc. But at least the masses will be behind some protective
barrier.

Greg