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Old 28th Jan 2010, 08:08
  #2500 (permalink)  
S.F.L.Y
 
Join Date: Dec 2008
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To criticise that BA crew is breath-takingly arrogant.
Do you mean there's nothing to learn from the BA accident? I really don't care about judging the crew, I'm interested in the mechanisms that led them to do what they did (or didn't). Pretending all what they did was perfect is also very arrogant. (just like the "I only listen to Phd holders" attitude).

Any glider pilot perfectly knows that on high aspect ratio wings slights speed deviations from best L/D have larger effects on the gliding perfs. High deviation below Vref caused by the AP attempt to land a thousand feet beyond rwy threshold couldn't deliver best gliding distance. I'm not judging the crew as I'm only interested in knowing why performances have been limited. I'm valuating comments based on their content, not on the "prestigious" degrees held by the posters.

I don't see much difference between the two incidents (in terms of human behavior). Here is why:

1 Both aircraft were on automated approaches
2 Both crews noticed speed going below Vref and both attempted corrections with thrust adjustments
3 In both cases these thrusts adjustments were infective and speed kept decaying
4 In both cases aircrafts lost the same proportion of speed and reached stick shaker while the AP attempted to remain on the ILS.

Whatever were the causes, step 4 was reached by both crews through similar processes. At that point (4) both aircrafts can't anymore follow the ILS. At that point it's just a matter of pilot inputs and trim position...

The 777 had enough height to drop the nose and recover some energy to control the impact. In the 737 the combination of nose up trim and max thrust pitch up momentum probably limited a similar nose down recovery leading to high Vz/high AoA impact. The trim positions reached by the AP in both aircrafts could have made a big difference in the outcomes. I don't see how so called "professionals" can decide whether one crew is to be blamed and the other one to be congratulated for the few seconds following step 4 since they had similar behaviors during the preceding steps.
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