IMO, any "tumbling-end-over-end" report would have to treated with reserve. As an anorak, I've been observing a/c of all kinds from the ground all my life, and even in broad daylight it's easy completely to misread the attitude and trajectory of an a/c - even during a simple steep turn.
Yes, that was what I was getting at, these things can be deceiving. I was once asked how on earth I was able (and how had I obtained display clearance) to "loop" a 7 tonne helicopter during my handling display, beginning from a base height of 50 feet agl. Of course, we weren't looping at all. The manoeuvre was in fact a 90 degree banked turn through 360 degrees, after a rolling 90 degree nose up climb and a slightly less steep descent. It was meant to look like a loop, of course and it worked because the crowd saw the top of the helicopter.