Lyman;
Re, "Without context, and perhaps there is none, all that aft stick is bizarre."
Without spending too much time reviewing old ground, I had some time ago posited the notion that the PF was executing one of the memory items in the UAS drill.
In the BEA Second Interim Report pgs 54 & 54, Section 1.17.2.4, it is noted that the UAS event was included in the 2008-2009 recurrent training season. The training included a booklet, the contents of which are briefly described in this section.
The training script for the recurrent simulator session in which the UAS event was included and which the PF First Officer had taken on February 2 2009, (the PM First Officer had received this training a couple of months earlier), required that the aircraft remain in Normal Law with no warnings triggered.
The UAS scenario used in this simulator session was a loss of airspeed information just after takeoff.
In such a case, the safe conduct of the flight is impacted and the memory items of the UAS drill are to be executed.
After ensuring that the autopilot, flight directors and autothrust are set to OFF and if below thrust reduction altitude (nominally either 1500ft AGL or more recently, 1000ft AGL), TOGA thrust is set and the initial "safe" pitch attitude is set to 15deg NU.
At slightly higher altitudes (thrust reduction altitude to FL100) the thrust levers are set to the "CLB" (climb) detent and pitch is set to 10deg NU. Above FL100 and if the safe conduct of the flight is still impacted, pitch is set to 5deg.
The last item in the memorized group states that once the aircraft is above circuit altitude or MSA, (Minimum Safe Altitude), the aircraft is leveled off for troubleshooting.
The FCTM (Flight Crew Training Manual) dated February 2007, though not the legal operational document (only the FCOM is) states that if the safe conduct of the flight is not impacted, the memory items are not to be executed and the crew must reference "part 2" of the QRH UAS checklist for correct pitch and power settings. In other words, present pitch and power settings are maintained while the QRH is brought out and the checklist read by the PM.
As pointed out by Owain Glyndwr, the failures resulting from the loss of airspeed information are graceful and do not present controllability problems. Loss of airspeed information does not require immediate action when in stable, level flight. So, what explains the immediate action?
I think the PF concluded that with the loss of airspeed information the safety of the flight was at immediate risk and was simply executing what he recalled from the earlier simulator session.
As the BEA Third Interim Report states, neither cockpit discipline nor SOPs were followed, and in combination with the effects of the immediate, strong pitch-up commands and subsequent aircraft response taking the aircraft out of stable, controlled flight, I think this prevented them from perceiving and then assessing what was happening.
The situation became immediately confusing as to why the airplane was behaving the way it did, (two momentary stall warnings, due strong pitch-up commands) and the returning airspeed information after about 28 seconds, and a likely clearing of ECAM faults as the airspeed data returned to normal, presented confusing signals to the crew. By this time the airplane was approaching the stall at the apogee of the climb.
Once the pitch-up occurred, a cognitive dissonance rapidly emerged from the differences between expected aircraft behaviour and what they were seeing/hearing. Putting it differently, the pitch-up was expected to be the "correct" response but it wasn't producing the expected stability. Normal perception of the stall warning was blocked because they were trying to resolve cognitive expectations with what was happening).
There seemed to be the expectation that the aircraft would respond at cruise altitude the way it would right after takeoff. This speaks to training and experience issues of manually flying transport aircraft at cruise altitudes and of knowledge and understanding of high altitude, high Mach number flight.
I'm speaking here as a pilot of course, but I think these are reasonable, if not at the moment theoretical, human factors.
gums;
Precisely.
Issues arising from this may be the loss of stall-warning below 60kts and some form of audible signalling when the trim is moving but I think the designers/engineers had a reasonable expectation that the aircraft would not be flown in these regimes by competent line crews, and that every contingency imaginable could not be designed against, not, at least, without prohibitive and difficult-to-justify cost.
I think the one very significant issue is however, the design of the UAS drill and QRH checklist which does not reflect with sufficient clarity what is stated in the FCTM. All we need do is review the PPRuNe contributions on this to see that the matter is indeed conflated even among those who fly the airplane. The fact that 36 other crews did not do what many here have claimed to be the "correct" response in cruise, (if above FL100, pitch up to 5deg) is evidence that there is a significant disconnect here. In fact I think even Airbus is confused about this.
Last edited by PJ2; 8th Mar 2012 at 17:41.