BOAC,
You are all ignoring the nose down pitch change that occurred each time nose down elevator was applied?
Indeed not. Which is why I have been hinting that this was a manually induced and prolonged deep stall.
Clandestino,
References contrary to your claim can be found in "Handling the big jets". third edition, page 119. Or any decent basic aerodynamics textbook, e.g. Atlantic Flight Training ltd JAA ATPL training handbook, Principles of flight, pages 8-14 to 8-16 in 2006. edition. Those were first that I dug out of my bookshelf and I can't publish excerpts due to copyright issues but if you really want to know what's written in them, i don't think you'll have problem finding out.
You said it yourself. BASIC aerodynamics. ATPL Principles of Flight leaves a lot to be desired. I suggest that you ferret a bit deeper into advanced aerodynamics.
A deep stall is NOT irrecoverable. A deep stall maybe harder to recover in a T-Tail aircraft because of reduced elevator effectiveness. It is the combination of both swept wings AND T-Tail configurations in aircraft such as the 727 that makes a deep stall more of a problem. Elevator/pitch rocking and induced roll are two ways to recover but these may take a lot of time and height.
Swept wing aircraft can all be made to deep stall if you have enough elevator authority.
But it doesn't follow that moving the Cp in stall forward results in pitch-up! If it were so in the real world, we would be in deep trouble and I certainly would not be writing this post but pushing daisies at certain quiet village graveyard.
Of course, pitch up may only be a problem if it's excessive or it's exacerbated by poor handling! I congratulate you. It is possible that the A330 lost elevator effectiveness because of vortex buffeting during the pre stall regime stall which caused excessive pitch up exacerbated by the full NU command led to deep stall entry.
Aileron Drag,
There was no bloody
locked in deep stall.
If adequate control authority is not available to recover you are in a deep stall. Usually because of vortex buffeting on T-Tails or, on other types, anything else that reduces elevator control margins.