GB;
Hmm, the "impossible" flat spin of a jet transport.
Ouch.
Not impossible, merely improbable given possible entry into a thunderstorm.
One thing flight safety investigators and specialists don't do is hitch their wagon to theories and stick with them in the face of new evidence. I would have thought (and did) that, as the impact is described, a high-speed vertical trajectory in a flat attitude/spin, (indicating a very high angle of attack), would have resulted in greater evidence of a) compression stress and b) evidence of shattering of parts instead of large intact structures but there it is.
How this conclusion was reached will be revealed in the coming days/weeks but at least we know more now and it will be fascinating to learn how this was concluded.