Old Carthusian;
Re, "But it is a human issue not a mechanical issue. [As PJ2 has mentioned...] this is not an issue with flaps or spoilers at all or with availability of information."
Given what we have, (and it isn't unreasonable to doubt that what we have is all that is available), this is a performance accident. The far more critical aspect of this accident is "Why?" At present I think it is not complicated.
Lyman;
Re, "What did the pilots mean, then, when they reported to the Captain, that they had no displays?"
The only reference to displays is when the PF states, "We haven't got a good display...", "...of speed", and the PM states, "We've lost the speeds", (IR3 p29, p74, English version). No other references to loss of attitude, or altitude information is made. Contrarily, a number of references to altitude and pitch are made which indicate that the displays were functioning:
"Reading the three instruments (the two PFD’s and the ISIS), the PNF noticed that the airplane was climbing and asked the PF several times to descend." - IR3, p74 English Version
Regarding their contributions to the captain's understanding and the captain's responses:
"In the absence of relevant information from the copilots, reading the information available on the screens (pitch attitude, roll, thrust, vertical speed, altitude, etc…) was not sufficient in itself for the Captain to become rapidly aware of the airplane’s situation. He did not then ask questions that could have helped him to understand the sequence of events." - IR3, p76 English Version
Re, "And when did the displays return?"
The displays did not disappear. But the CAS indication did and it reappeared just under 30 seconds after the initial UAS event:
"At around 2 h 10 min 34, the speed displayed on the left side became valid again and was then 215 kt; the speed on the ISIS was still incorrect.". - IR3, p74 English Version
...and from IR3, p75:
"At 2 h 11 min 06, after several attempts to call, the PNF was anxious again about the absence of the Captain. This anxiety probably increased the stress for the PNF who was faced with a situation that he didn’t understand.
A second later, the speed on the ISIS became valid again. ADR 3 being selected on the right side PFD, the speed for the PF also became valid again. It was then 183 kt and the three displayed speeds were consistent. This brought no comment from the crew." - IR3, p75, English Version
I am well aware of the underlying assumptions behind these tentative conclusions but from experience with and knowledge of the airplane they are not unreasonable.
Last edited by PJ2; 27th Mar 2012 at 01:28.