Three possibilities as I see it:
1- EgyptionAiresque Jihadi Moment
2- inadvertent locking of the door and then the pilot has heart attack or stroke
3- Some kind of blackmail (we’ll kill your family if you don’t comply) possibly by the Russians who wanted one of the passengers dead and the act of murder murky and unclear
In my mind, #1 is most likely, #2 is less likely, #3 is least likely.
I don't think so. Watch the video at post 7
Nope. The official word is that it was an intentional act.
The co-pilot took all intentional acts to cut communications, override the door mechanism to keep it locked, put the plane into a dive and accelerated into the ground.