One extra bit, which I cannot remember to have been posted yet. With these prerequisites
- sea surface temperature was reported to be 27 - 28 degC, that is ISA+13.
- cruise speed M.82 (my assumption, to be corrected)
- weight approx. 210 t (took the same like snaproll3480)
the actual AF A330 QRM says for ISA+15
MAX AND OPT ALT
FL357
ENGINE ANTI ICE ON -1100 FT
TOTAL ANTI ICE ON
-1300 FT
Now, go figure what might happen when they had to
- manually fly with alternate law (hence without stall protection) in turbulent air
- tried to fix the assumed possible sensor icing (whichever) with total anti ice on...
MAX ALT would be reduced to FL344 (in clean air, that is), which means it was near impossible to keep the plane from stalling. Even if my numbers are slightly incorrect for the actual flight, the turbulences they encountered surely would have taken away every margin they might have had.
To me, this would be enough to draw the deadly picture.