Originally Posted by
HazelNuts39
RE: Hyperveloce (#4134)
Jeff,
The Air Caraibe incidents have been properly analysed and the stall warnings have been found to be valid. I strongly suspect that the other events have been similarly analysed with the same result. The only result of Air Caraibe's meeting with Airbus 'engineers' in Toulouse has been that Airbus "would consider a possible amendment of the checklist" (my own words). Has the checklist been amended?
regards,
HN39
I don't know if the check-list has been amended (Airbus said it was working on it at the end of 2008) and if it was, if it could explain the differences shown by the BEA report between Airbus and AF SOPs.
I agree with you HN39, that AC report shows that the AoA exceeded the 4.2° threshold when the stall alarm sounded. But this 4.2° threshold is probably different under a normal law and normal airspeeds ? (since it is derived from these two parameters, and from the aerodynamical config.). Hence to me, this event would not be independant from the event "Pitot freezing" and to prove my point or disprove it, the only piece of information needed would be to get the normal AoA threshold (under a normal law) and compare it to 4.2°. I don't know if the AoA exceeding 4.2° was a definitive sign of a "valid"/real stall (probably not, since the plane's AOA reached 4.48° without entering a stall or having shown precursors of a stall), or if it was an AoA threshold with a margin to take in account the degraded situation (ALTN2).
Besides, there are two stall warnings, the one triggered by the alpha prot. (lost in ALTN2) and the one mentioned above (comparison to 4.2°). In this latter case, the stall warning comes with the cricket sounds: the AC crew heard the cricket when the stall warnings sounded, but not all the other crew: the AF 908 reported "stall warnings without the cricket sound".
Jeff