PPRuNe Forums - View Single Post - Airbus trepidation... convince me otherwise!
Old 12th Jan 2012, 15:09
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cosmo kramer
 
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Pulling up is the instinctive reaction to counter a stall? I didn't think so either.
My theory:
(and yes it should be obvious by now that I don't like that Airbus philosophy, but at least I believe I have it backed up with arguments as to why)

I would say that in general, it is very natural to pull back when you are going down. You have to remember that not once in the CVR do they discuss the possibility that they are in fact stalled, despite the oral warnings. Hence, it would be quite reasonable to conclude that they were not aware that they had stalled.

With the first problem being unreliable airspeed, it may have caused them to subconsciously dismiss the warning. Further another Airbus "feature" may have enforced their belief that they in fact where not in a stall. As they pulled back and the speed dropped below 60 kts the stall warning seized.
Question: How can you design a stall warning that stops when the airspeed get extremely critical? How can the "logic" dismiss a speed of less that 60 kts as being "invalid" when the air/ground sensor is in flight?
Rhetorical: Oh yes, I forgot, it's not necessary since it's obviously impossible to stall an Airbus!! (my bad, since: "we must try and understand it's logic").

With no tactile feedback from the stick (which would have presented itself as unusually high back pressure in a conventional aircraft, like mentioned in previous post), the only indication that something was terribly wrong would have been the high pitch presented on the PFD.

Another question: Correct me if I am wrong, but is the normal GPWS maneuver for an Airbus full back pressure and full thrust? Oh, they were in another mode where that doesn't apply, you say? ("we must try and understand it's logic").

Conclusion:
With the assumption that the aircraft is flying it is perfectly natural instinctive reaction to pull back to arrest a descend.


Of course It's unfortunate, to say at least, that they didn't recognize the high pitch, but with turbulence, bell and whistles and an aircraft providing no feedback what-so-ever I won't be the judge of that. From reading the transcript it seems like they got really confused and overloaded, and they certainly didn't get any help from the aircraft.

Surely, the situation could have been handled better with pitch and power, but with daily ops with "path stability" and other concept that goes against the laws of nature, is pitch and power even a concept in the Airbus "logic"?

Lack of training... Yes, an inherent Airbus problem, since you can't make up the daily training on the line with simulator sessions twice a year. The problem with the Airbus in my opinion is, that you can't train flying it in alternate or direct law. With a conventional aircraft you can train "direct law" raw data daily, and this is the worst situation the automatics will drop you into. With Airbus on the other hand, when you have a problem on a dark stormy night, the aircraft itself drops another problem on you lap - that you get an aircraft that you are not used to handle and never will be properly trained to handle!
Of course this could be solved by mandating that all Airbus pilots get a simulator session pr. week, where they can practice flying in the lowest level of automation! (they would still get less practice then an eager pilot on a conventional aircraft).

To say that AirFrance managed to pair up the 3 worst pilots in their fleet and their incompetence was the cause of the crash is simply too easy a solution. Im am not buying it, and I feel sorry not only for those onboard but also for those the pilots left behind, who now have to live with the public pressure that their loved ones, who may have been dutiful and decent pilots, killed a lot of people.
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