Thread: Habsheim
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Old 6th Mar 2014, 12:02
  #594 (permalink)  
Join Date: Jul 2009
Location: France - mostly
Age: 80
Posts: 1,689
From the NTSB Performance Group Chairman’s report on the Hudson river ditching:

At 15:30:39, as the airplane descends through 50 ft, the stick moves aft more
abruptly, reaching its aft limit (16) at about 15:30:41, and remaining there about 2
seconds, until touchdown at 15:30:43.
The elevator response plotted in Figure 15b indicates that during this time, the elevators
move trailing-edge up starting at 15:30:37, reaching about 4 at 15:30:38, and then move
abruptly down to about -1 at 15:30:39 before increasing again to about 4.5 at 15:30:41. In
the last 2 seconds of flight, the elevator deflection increases about 1, from 4.5 to 5.5.
Figure 7 shows that between 15:30:36 and the touchdown at 15:30:43, the pitch angle
increases from 9.5 to 11 and then settles back to 9.5, even though in the last two
seconds the left longitudinal side stick is at its aft limit, and α is below αmax.
It seems to me that the elevator response to the sidestick input at Habsheim was quite similar, except that the sequence was interrupted by the airplane striking the tree tops.

What is puzzling to me is that the simulator did not reproduce it when capt. Bechet flew it to duplicate the accident sequence. In that simulation the elevator moves immediately nose-up, and the airplane pitches up 5 degrees in 2 seconds. Why is it different?

Sorry for posting when I should have thought a bit longer. Both moved the thrust levers forward at 120 kts, 12 deg alpha. The difference is in pulling the sidestick back - Bechet at the same instant and Asseline 3 seconds later. So Bechet was still in pitch control law when he pulled the stick back while Asseline was in alpha-prot. Nevertheless, Bechet would still have hit the trees if he had not been in a simulator.

Last edited by HazelNuts39; 6th Mar 2014 at 15:45. Reason: P.S.
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