PPRuNe Forums - View Single Post - Eventually !!Probe Blames Captain for GF Jet Crash
Old 23rd Jul 2002, 14:02
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Covenant
 
Join Date: Jan 2001
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Chuck Hog

So you are saying that the official investigation overlooked, either deliberately or inadvertently, something in the data that you have managed to discover from looking at a couple of FDR graphs.

For what my opinion is worth, I read the graphs differently from you anyway:

1) The captain commanded significant nose down input between 16:29:43 and 16:29:53 - more than ten seconds of it anyway. During this time, the aircraft went from about 6 deg nose up attitude to about 16 deg nose down. The aircraft responded to his aft sidestick commands thereafter by reducing the nose down attitude to about 5 deg nose down at the end of the FDR recording. This strikes me as ain aircraft doing exactly what it's been told to do. The elevator response (brown and grey lines) confirms this.
2) Soon after TOGA power was selected, trim moved to around about 1.5 deg nose down and stabilised there during which time the aircraft was established in a stable climb. When the captain started to command the nose down on his sidestick, the trim blipped down a fraction, maxing out at maybe 2 deg nose down and finally ending at about 1 deg nose down.

I don't believe you are telling me that this trim graph indicates that the aircaft flew itself into terrain against the commands of its pilot! All the evidence points to CFIT. There is no evidence from the CVR that the pilots were surprised by the response of the aircraft to their command input. The PF didn't pull back as if he was fighting to bring the nose up. The PNF didn't even activate his sidestick. How do you answer those rather more pertinent facts?

The other incidents that have been mentioned regarding the A320/A340 response in windshear do not have any real bearing on this incident, and particularly not on the question you have raised about the automatic trim. A40-EK was responding only to TOGA selection and had established a steady climb with nose-down trim. In the case of windshear, it is likely that the FBW system was limiting command authority to the elevators because of approaching stall conditions.

I'm sorry Chuck Hog, but I have to say that I think what we are seeing from you and the other Airbus scaremongers is technophobia (I give the benefit of the doubt that it is not just parochialism or, worse, protectionsim). No matter how advanced we become technically, and how educated or professional we are, we still do not really trust machines deep down in our psyche. In essence (and I apologise for crossing threads here), this is why we had the tragic loss in the recent mid-air collision over Germany. In the face of a conflict between advice being supplied by a computer, and the reassuring human voice of the ATC, the Russian pilot chose to trust the human.

Unfortunately, as has been amply demonstrated so many times, most tragedies are caused in some way by human error. If we could bring ourselves to trust machines more, maybe the world would be a slightly safer place.

Last edited by Covenant; 23rd Jul 2002 at 16:53.
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