[Gritty]

From the pictures I've seen, the large debris field (mostly small pieces extending over several ridges and valleys, some major pieces widely separated in the valleys) would indicate a complete breakup of the aircraft before it hit the ground - but not at high altitude as the wreckage is too concentrated. That is puzzling, but the pictures we have seen may not be of the complete scene. From the available ones, there does not seem to be a definitive point of impact.

I'm sure the flight data recorder will clear most of this mystery up. This crash certainly has a lot of strange things going for it and it will be "one for the books".

One thing seems certain at this point, though - the pilots were somehow incapacitated and probably early on in the beginning of the accident sequence.

[kjam22]

The other thing that is interesting.... If I heard the facts correctly..... it descended from 38,000 to 2,000 in 18 minutes. If on a straight line, that’s a nice round number of 2,000 feet per minute.

[Tzfat]

From the pictures I've seen, the large debris field (mostly small pieces extending over several ridges and valleys, some major pieces widely separated in the valleys) would indicate a complete breakup of the aircraft before it hit the ground - but not at high altitude as the wreckage is too concentrated. That is puzzling, but the pictures we have seen may not be of the complete scene. From the available ones, there does not seem to be a definitive point of impact.

I share your perspective. The debris field does not make sense for an impact with the ground. Unless it was vertical. That would seem to indicate an intentional impact, in light of a long descent. Either the pilots were dead or unconscious, or this was intentional.

A low altitude disintegration is the first thing that comes to mind. Bomb, or airframe. Multiple explosions could do it to. One at high altitude, another altimeter triggered device lower.

[Boundless]

re: I’m sure the flight data recorder will clear most of this mystery up.

Don’t hold your breath. News reports say the CVR memory is “unreadable” and the FDR memory card is missing (with an implication of dislodged in crash, not removed before flight).

[motor_racer]

From the pictures I've seen, the large debris field (mostly small pieces extending over several ridges and valleys, some major pieces widely separated in the valleys) would indicate a complete breakup of the aircraft before it hit the ground

Can't agree with this. I"m an engineer experienced with race car crashes at very high speed. We design them to lose parts so they will slow more quickly. An aircraft that broke up mid-air would consist of a number of fairly large pieces plus some small ones. All the pieces would have severely increased aero drag, and individually much lower energy, than the whole plane together. That would increase the likelihood of fairly large pieces remaining, as they would lose a lot of speed before impact.

A land speed record car crashing at 450+ mph turns into shreds. If you can make the car come apart, you can give the driver an opportunity to survive in a hardened cockpit cell. Of course, the initial deceleration will probably kill him.