The only reason I mentioned wake turbulence is that its a good way to pop a perfectly serviceable light aircraft into the ground. Its also a feasible 'gotcha' for an instructor to overlook. I think its very unlikely that the instructor was demonstrating or training incipient spins at too low an altitude to revcover should a spin develop. The Tomhawk has been discussed at length on this forum and its 'wobbly' tail in a spin has had people worried, but those worries were quashed by others who said that the tail had never actually failed in a spin. This makes structural failure seem unlikely. From a skills point of view, P1 was an instructor who presumably was competent (the Tomahawk is after all a simple trainer rather than a high wing-loading complex widow maker) This makes me believe its unlikely that the aircraft was mis-handled in some way. This path of deduction leaves only a few probable causes; That neither pilot was able to handle the aircraft (carbon monoxide poisoning). That there was some sort of altercation/sucidal student or instructor (unlikely but has happened before). That there was a structural failure (already discussed as unlikely) That the aircraft was made uncontrollable by an external factor. In CAVOK close to the ground, this may be wake turbulence. I don't know that this is likely as I don't know where the aircraft was operating, but it seems fesible. Out of all the options, I would regard the most likely as either wake turbulence or CO poisoning. I sincerely hope it was the latter.