Thread: Habsheim
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Old 6th Mar 2014, 09:44
  #593 (permalink)  
AlphaZuluRomeo
 
Join Date: Nov 2010
Location: FR
Posts: 478
Originally Posted by CONF iture View Post
That it was a few seconds or ten changes nothing to the fact that the elevators for that period just did the opposite of the pilot request. The FCS had simply no intention to let the pilot increase both the attitude and the alpha
Yes, clearly that is fact, and amply demonstrated.
Noteworthy is that "that period" is quite short.

Originally Posted by CONF iture View Post
whenever 2.5 deg were still avail.
OTOH, that is not.
From an aerodynamic point of view, there were probably more than 2.5 deg before stall. From an FCS point of view, for this to be correct, the FCOM should read that alphamax was to be attained immediately and without any damping.
Does the BEA report or the FCOM read this? No. You just quoted both.
The NTSB report on Hudson event, and numerous other discussions here and there have put forward several explanations as to why alphamax(17.5) would, in certain circonstances, not be reached immediately.

Originally Posted by CONF iture View Post
Right on, alpha max all the way for CONF FULL, no hesitation, even possible alpha max transient overshoots.
Yes, clearly that is fact, and amply demonstrated.

Originally Posted by CONF iture View Post
That's how the alpha protection feature is supposed to work.
No. That's the way it works when in the conditions of the test flight. Which are different from the conditions of Habseim flight.

Originally Posted by CONF iture View Post
Gordon Corps just proved them wrong.
No. See above.

I'm sorry to be a bit harsh, CONF. I have no certainty myself as to why precisely the FCS did what it did on the last few seconds before the crash at Habseim. I would like to be sure, but I'm not.
The BEA says it's normal behavior, Airbus says nothing (or more or less rephrase the BEA report), and external experts don't have access to the code or specifications of the A320 FCS.

But there have been a number of attempts from contributors here (and elsewhere) to explain this "why" (sometime using the NTSB contribution, which had access to whatever it needed to explain Hudson).
I judge those explanations convincing.
You seems not, but don't explain yourself on that matter.

As neither of us can proove them right, or wrong, without access to the code and specifications of the A320 FCS, we can either agree to a "stalemate", or you can try and explain why you (seem to) dismiss each hypothesis.

Cheers.

Last edited by AlphaZuluRomeo; 6th Mar 2014 at 14:16. Reason: precisions on 2nd point
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