Anecdotal "evidence" quoted here, indicates that there might have been up to three ground runs before the final fourth run and fatal flight!
'Jetpod' air taxi entrepreneur killed in test crash
Circumstances of the accident have yet to be established but a witness at the crash site tells Flightglobal that the aircraft had already made three runs, during each of which there appeared to be engine problems.
It made a fourth attempt to become airborne, he says, and took off at about 12:45, entering a "sharp climb". It appeared to suffer a problem with its left-hand engine, he says, at about 500-700ft, then yawed sharply to the left and crashed.