Originally Posted by Machinbird
Those that wish to add a large turbulence/updraft element to this loss of control seem to be putting unnecesary sauce on the stew. Occam's Razor applies.
Occam's Razor, yes and also simple physics.
The potential/kinetic energy transfert calculation shows that at 37500 ft TAS should be 413 kt @ Std + 10 assuming constant thrust and drag. The BEA reports CAS 215 kt (M 0.68) at this altitude which gives 399 kt TAS @Std + 10.
Factoring decreasing thrust with increasing altitude and a bit of extra drag due to manoeuvring should easily account for the 14 kt discrepancy.
In no way the a/c gained energy as would have been the case in an updraft.