@DW
I do not agree, please recheck.
BEA is talking about the identical two warnings in the same timeframe. It adresses the logic of the stall warning, and that it should have sounded longer than it did and three times instead of two times. And it didnīt sound that long, because the threshold, at which the stall warning is activated, increased to about 10° AOA (which is not depicted in the FDR- trace with the green line) due to the abnormal (not actual) Mach number. The threshold is lower at high mach, higher at lower mach. As mach was wrong due to the iced pitots, the warning threshold was set too high and therefore the warning sounded too short.
If you compare the mentioned times from BEA with the
figure 62 of Final report, you will see that the warning sounded shorter than depicted looking like spurious and thus not understood by the crew. And that is exactly what BEA states under 1.16.3.2 Analysis of the operation of the stall warning.
Why the wrong movement of the threshold like mentioned by BEA is not depicted in Figure 62 FDR traces with the green line, i dont know. But the faulty mach is depicted above. Maybe this line has a different origin and is not mach dependent.
The warning was valid, however it was not presented to the crew in the apropriate long time frame due to the iced pitots.