Probably been said before better.
FWIW, clean, the wing will stall between 11-12 alpha, without the activity of autoslats (don't know if the A330 would have that at FL350...).
What the crew face is a known area of turbulence, likely causing variations of ATT, Mno, THR, and some short period variations of IVSI & ALT. At some point in the encounter, the pitots fail causing erroneous CAS data, which upsets the PFD CAS/Mno displayed, and would affect the ATR THR settings by altering the targets. (IIRC, the EPRL will still be correctly set though using the engines own P1/T1 probes). The only real indication of speed for the crew is the ATT of the aircraft which is being affected by turbulence... and so is difficult to evaluate. The alpha is not displayed on the PFD's as a discrete display, (on Boeing's the AoA vanes provide one of the inputs to the minimum speed displayed on the PFD... don't know about A330's)
The stall warning would still be valid if occurring, but may occur at the same time that the crew get ambiguous warnings such as overspeed etc. Coupled to all of this is that until the PRIM/SEC detect that sensor error(s) exists, the flight controls are getting inputs from false data, including potentially both high and/or low CAS conditions where FBW envelope protections occur.
This condition is bad enough in day/VMC conditions, in night/IMC/turbulence, distinguishing what the error is and what valid sources exist would be challenging.
This event also follows the QFA072 A330 upset where the causal factor was the AoA vane data to the ADIRS.
The final indicator of performance remaining to the crew was the pitch ATT (theta) relative to the horizon, which infers the AoA, and therefore CAS. This is functionally removed due to the turbulent state as being accurate information.
IMHO, what is surprising is that on numerous occasions previously, this form of ADIRS data failure has not caused an accident.
The recovery from an upset without valid primary data is at best difficult, and in night/IMC I would wager improbable for the first crews to encounter such a case. Would the next crew fare better? I would hope so.
[B]"Learning is not compulsory... neither is survival" [/B
]
W.Edwards Deeming (1900 - 1993)
[note: if the A330 does have autoslat capability at altitude, the potential for aggravation of the flightpath management exists, they cause no end of problem at high mach... I don't have the books here with me at home to check the AI systems...]
regards,
FDR.