Just to summarize what we know up till now:
- Aircraft suddenly descended from FL380 at around 6000 fpm with no communications until impact with ground.
- Continuous long straight ground track and relatively large pieces of wreckage remaining indicates low to medium energy impact with ground at a shallow angle (I recall the An12 that crashed on approach fully configured for landing somewhere in central Africa after descending into the ground in patchy fog left a very similar ground track and wreckage)
- At least one engine produced some power at impact.
- Two on board are still unaccounted for.
- Weather at accident site was clear at time of impact, some contradiction whether there may have been T/S cells along the original flight path.
- Pilots plenty of experience both in terms of hours and on type.
I find this the most puzzling accident since AF447, I'm sure Embraer will go to very great lengths to figure out what happened, if will not be obvious from FDR/CVR.