The whole thing was brilliant (flamethrower on Dominator completely ineffecutal though!) and hilarious. Especially the snow depth test as previously stated.
But I'm not so certain that it was staged - the bumpy landing and mini-groundloop looked sort of plausible, and, having been involved with them on a similar but unrelated aviation film project, I reckon the TG lot would manage to balls something up to the required extent for it to happen. That said, I am somewhat gullible