of course speculation but i guess there is not much secrets in this tragedy .
probably they realized they do not have the performance to make it over the mountains infront so they tried a sharp 180 deg turn to save the day . during the turn , loosing more and more speed trying to maintain altitude , one wing stalled and they went down like a rock without being able to recover .
investigation surely will focus the reason for the lack of performance .
( just to heavy on this hot day or engine problems )
i guess thats all .