Originally Posted by
DJ77
Hyperveloce:
The FCOM don't say airspeed indications, either exact or erroneous, are removed from the PFDs and ISIS (otherwise, you could not sort them out in case of ADR DISAGREE).
My wording was not precise enought, sorry for that. The Air Caraïbe safety report explains how the PFD are reconfigurated in the event of an ADR disagree: "SPD LIM", RED FLAG (like in the AF 447 ACARS btw) and many of the following indicators are lost: VLS, S, F, the green dot, Vtrend, Vmax, VFEnext, Vsw (resulting from the CAS monitoring process which excluded the 3 ADR and triggered the ALTN2 and PROT LOST). Though we know that the Vtrend is still displayed (-50 kts during the Paris-Antananarivo flight), and I wonder if it is opportunate in the case ADR disagreement event.
But in the case of the AF 422, when it is said "réapparition de la vitesse puis conditions VMC", what does exactly mean "réapparition de la vitesse" ? Back to the normal PFD speed display with all the previously lost speeds indicators ?
There are other cues, like pitch/thrust or pitch/vertical speed relationships.
As was already mentionned by others, stall warning procedure is different from stall recovery. the former was very well described by HazelNuts39 in post #4100.
DJ.
Yes, I was assuming that the nose had been lowered a bit (and maybe the thrust had been increased) with the idea to avoid stalling conditions, not to recover from these (and in my thinking [*], these would tend to be spurious). Is the pich&thrust procedure only applicable to maintain a constant altitude (zero vertical speed) or is it easily implementable during a descent ? Once the plane is in descent, given moderated turbulence and probably no outside clues, how much time would you need to monitor the time evolution of {pich; thrust; altitude evolution or vertical speed} to get a sufficient confidence about your flight point ? Because it seems that 10s, 30s or 50s could lead to different outcomes if my rudimentary computations bear a sufficient degree of representativity.
Jeff[*] would there be also the opposite case (overspeed alarms, nose up/climbing and critical loss of speed in high altitude, nose up stall) ?