The loss of airspeed indications or disagreement event due to icing in the tops of cumulonimbus clouds in the tropics was very common in the Airbus A330 and A340 series prior to this accident, as many reported and many more unreported events, have shown. But why in this instance did it lead to a crash?
In essence:
1. In response to the loss of airspeed indication the RH pilot pulled the aircraft nose up...why?
2. The aircraft then zoom climbed some thousands of feet and lost flying speed to the point of stall.
3. The LH pilot did not identify this critical pitch attitude change with the consequent performance loss or correctly call or otherwise respond to it.
4. Approximately half way through the recorder trace shown above (Capn Bloggs), the Stabilizer auto-trimmed to full nose up in response to the RH pilot's aft stick commands.
5. With the subsequent control law reversion, the aircraft was then doomed to a no-stall-recovery situation with the Stabilizer stuck full up (as the Stab autotrim feature was lost with control law reversion). One of the pilots should have re-trimmed the Stabilizer sufficiently nose down with manual inputs using the pitch trim wheel to allow recovery. This did not happen...why?
I have seen similar situations many times during simulator training when teaching high-altitude jet-upset and unusual attitude recovery training modules on the Airbus series. Sometimes, intervention by the simulator instructor is required to grab the PF's hand and place it on the trim wheel to reveal (voila!) the ever so simple solution to manually retrim the stabilizer enough to to enable sufficient elevator authority for stall recovery. The trainee never forgets this lesson.
Putting aside the problems of stabilizers vs elevator authority (incidentally, problems that affect most airliners) for a moment...
...what troubles me is the question...What is deficient in Air France's Cadet and FO pilot training that allowed this situation to develop without recognition by at least one of the pilots of the power/attitude/performance incompatibility event that was consequent to the initial loss of airspeed fault?
A very sad situation and one that I hope Air France and possibly other affected Airlines will rectify...
Last edited by FlexibleResponse; 14th May 2013 at 14:53.