PPRuNe Forums - View Single Post - AF 447 Thread No. 9
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Old 25th Jul 2012, 03:43
  #692 (permalink)  
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Join Date: Jun 2009
Location: florida
Age: 81
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No doubt the questionable CRM is critical to this accident. Then there's a FBW system that could be improved, but that comes later in the post.

I was struck by the "brief" briefing when the aircraft commander left for a break. I heard no clear assignment of who was really in charge and who was simply flying at the time. Could be an AF standard procedure and such, I don't know. But I would prefer to have the duties and such clearly briefed.

I also heard/read on the CVR transcript the PNF say something to the effect that he had three indications of a climb and advise the PF to stop climbing. Did I get that wrong?

As most here know, I am disappointed in the lack of AoA inputs to the system when airspeed is unreliable. I shall not debate the issue of an AoA display any longer if the rank and file of the transport pilots here can't handle it or don't want it or don't think it would have helped.

OTOH, a FBW system advertising all the "protections" should certainly rank AoA very high. Airspeed inputs play a large role on the "gains" ( control surface deflections to achieve the commanded Nz or roll rate), but body rates are there by default and help a lot.

If the system designers do not use AoA sensor inputs ( cones or vanes) once speed is deemed unreliable, then why not use the obvious AoA available from the inertial system and attitude reference ( derived from inertial or a separate gyro)?

Subtract inertial flight path vector from pitch attitude and you get AoA - voila!. Then use that for stall warning, but mainly to provide the "protections" the drivers are expecting. Of all the "protections", the two that seem to be paramount are total Nz and AoA. The others in the myriad of laws/ reversions seem nice, but not as critical to basic aircraft control.

From the crew reactions, including the aircraft commander's, I cannot help but think they thot that the AoA "protections" were still in effect. "You can't stall this airplane".

that's all I'll say for now, and may comment about corporate mentality and such later.
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