infrequentflyer789
Thanks for a meticulous and thoughtful reply. I quote the initial BEA text when they sought to describe PF's actions at a/p drop. One can fall back on the dual language, made an issue here, but I prefer to place more confidence in the text as translated, to avoid weasel wriggling.
Some thoughts: The PF's actions were initially "Mostly Nose Down, with alternate roll left and right." Nose down is allowed when the bus is intitially dealing with Overspeed, but gradually ND becomes unavailable, and instead, it is replaced by auto NU, adding to Pilot input, if any.
The THS is also unavailable in Overspeed mode, so that explains the "loss" of THS TRIMOUT after the initial .7 degree TRIMUP. So we are left with a climb of robust nature, and little ND, until just at STALL, where the THS, reinvigorated, cycles all the way NU. Is this from "Memory"?
What does the Bus do if it is in Overspeed after identifying and reacting to it, but then speeds are lost?
Keep climbing? What is the nature of the annunciation of Overspeeding?
I notice your discomfort with a connection twixt UAS and the STALL. I share it. I also am not at all convinced the Pitots misbehaved in any way.
Just as the VSIs were reading "pegged" and "true", these probes could have been legit in their sampling, and the computer confused a "discontinuity" in airspeed with "discrepant" readings at each probe. The a/c apparently can react to these discontinuities as if it is discrepancies, instead. What if the initial airmass shear was additive to IAS? Overspeed determination? What if diminishing in IAS? If sudden, as shear is, could the drop have been 60, 80, 100 knots? Could such a drop in IAS have triggered the "zipper" at VS/SELECT prior to loss of autopilot? There was a WINDSHEAR REPORT on the ACARS, as there was also TCAS alarm?
I mention TOGA and 15 degree PITCH UP not to include it as an option at altitude, but to include it in the PF's muscle memory, and training. It is also possible he selected TOGA to attempt to get the NOSE UP, having not realized the NOSE was UP as high as it was already.
For three minutes, the Pilot was seemingly convinced the a/c had "some crazy speed". The PNF was not convinced, but neither was he ready to take the a/c into a Steep NOSE DOWN recovery. When Captain returned, he never seemed convinced either way, and his presence may have been a fatal distraction to the two at the helm.
So it is possible yet to retain an open mind. Demonstrably it is also predictable to judge the pilots incompetent in the court of easy chair PPRuNe jurisprudence.