PPRuNe Forums - View Single Post - AF447 - French prosecutors sends AF to court for negligence
Old 19th Jul 2019, 00:44
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phylosocopter
 
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Originally Posted by UltraFan
May I suggest (regardless of anyone present) that this course of thinking was exactly what brought that plane down. I have to do something! Thought the pilot. WHY!? Wasn't on his mind. The wings were level and the plane was flying straight. The attitude was exactly fine. The engines were spinning and served them perfectly well. They reduced speed to react to turbulence. The only thing worth stopping and thinking about in that particular situation was what to order from the galley.

Honestly, I can't think of another major accident, let alone a crash, that resulted from a situation where, to save the plane, pilots had to do exactly nothing. They were busy doing nothing before the incident, they had to remain doing nothing during the incident, and after the incident, they should've continued diligently doing nothing.
ahh as soon as to AP disconnects, the craft will start to roll! some intervention is required to keep wings level after AP disconnect.

my question is , were they at that point (immediately after AP disconnect) seeing a raw gyro attitude display or were they seeing some flight director telling them to go up?

My view is that BOTH the manufacturer and the regulator should be facing questions here because the state of alarms and displays at time of unreliable airspeed is not defined in regulation (as far as I can see)

edit.... have now found this discussion of the accident report that answers some of my question at
https://www.ainonline.com/aviation-n...pitch-commands"A major new finding in the final report concerned the flight director, which normally displays symbology on the pilots’ primary flying displays that give guidance on control inputs to reach a desired steady-state flightpath. After the autopilot and autothrottle disengaged, as the flight control law switched from normal to alternate, the flight director’s crossbars disappeared. But they then reappeared several times. Every time they were visible, they prompted pitch-up inputs by the PF, investigators determined. It took them a long time to “rebuild” what the flight director displayed since this is not part of the data recorded by the flight data recorder.The BEA acknowledged that the PF might have followed flight director indications. This was not the right thing to do in a stall but it seems that the crew never realized that the aircraft was in a stall. Moreover, the successive disappearance and reappearance of the crossbars reinforced this false impression, the investigators suggested. For the crew, this could have suggested their information was valid.None of the pilots recognized that the flight director was changing from one mode to another because they were just too busy. The PF may have trusted the flight director so much that he was verbally agreeing to the other pilot’s pitch-down instructions, while still actually pitching up.The BEA’s report includes significant recommendations about the flight director. One of them calls for European Aviation Safety Agency to review its “display logic.” The flight director should disappear or present “appropriate orders” in a stall."
from

Last edited by phylosocopter; 19th Jul 2019 at 01:15.
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