RE: What would you do?
I'm big on using a spotter and being one too.
My spotter/race caller/buddy and I were at a fly in where there were ususally 2-5 planes in the air all day. We heard a turbine spool up at the far end, not cool IMO to be rolling by pilots WAO. It's good form to get past the pilots before punching the gas. So this thing is winding up and my buddy calmly says he's not looking good, then a little less calmer says heads up and runs for it! Nice guy eh? Fortunately for me the jet hit a piece of rebar holding the little plastic snow fence and stopped short of hitting me.
I've also been hit by crash debris while in the pits a guy lost one that pounded the ground. Got a nasty bruise on my hip when the .61FX separated and bounced into me.