Short sequencing of a likely scenario
Gentlemen,
here is my own offer of a scenario sequence. All of this to be taken as an opinion. I would not bet my life on it, but it is the best I could come up with, with great outside help :
1 - high altitude ice crystals (outside CBs but inside thin layer of high altitude clouds around them - red returns on infrared satellite pictures).
2 - ice crystals block pitot probe drainholes (over-reading of IAS)
3 - Unreliable airspeeds -> A/P kicks OFF, along with other stuff
4 - a nasty invisible trap is set through FCPC2, no notice to the crew
5 - crew recovers from UAS without any upset
6 - UAS appears over, F/D bars reappear (see AD)
7 - crew reengages A/P, thinking the problem over
8 - trap is sprung, A/P kicks OFF again in violent upset (hard pitch-up)
9 - upset is not recoverable or not recovered (I expect 99.9% of airline pilots to fail that one)
10 - upset ends up as a deep stall or slow spin to the surface
This means the a/c likely did not crash right after end of ACARS sequence. The Cabin Vertical Speed message looks (to my opinion) like a consequence of FMGEC1 fault triggering a CPC reset or change of configuration, not a real descent (other messages exist for relief valves and other conditions).
Comments, questions and counters welcome.