for starters, as great as flight aware is, its not always that accurate. I have reviewed flights of my own that have suddenly zigged out into then ext state when i canceled IFR or flight following. Other times i have seen places where my route just completely stopped tracking (usually with a change from one ARTCC to another ARTCC while en route) giving the appearance that my flight vanished at cruise altitude.
I wouldnt jump to the conclusion that just because the flightaware.com route ends at a specific point that this is an accurate indication as to where the aircraft went down.
We can observe one thing though, it theoretically reached cruise altitude.
In that region of the world i would assume volcanic ash to be a culprit if there was recent volcanic activity (speedbird 9 anybody?)
another culprit, especially in the 200 series would be the un-commanded turbine rollback. however its unlikely as it should have been fixed through service bullitins and Airworthiness Directives requiring installation of fuel pump heaters if i remember correctly.
Super cooled water/ice formation which overwhelmed the aircraft's anti-ice de-ice systems a la Air France a few years ago could be to blame.
or an act of terrorism is always to be considered.
that said, it is rare that a plane crashes in the cruise phase of flight unless some sort of mid-air collision or major mechanical malfunction takes place. As these crashes tend to occur during takeoff or approach/ landing.
Im sure updates will begin to stream in soon as search efforts proceed.
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