He's technically correct but that's why Airbus tells pilots, in nice big bold letters, that you have reduced protections in those modes.
I'm not sure why this is an AF447 comment...if the pilot had left the stick alone, neutral stability would have saved his butt.
It was pulling nose up that really got them in trouble, and would have on an airplane with positive or neutral stability.
The assumption that simply letting go of the stick would have saved them does not appear to hold up to scrutiny. I found this particular gem by OK465 in the A320 OEB thread from one year ago:
Originally Posted by
OK465
All we're saying is that once this energy decay situation is established, there is no need to hold the SS aft, for the sequence to play out. Hands-off will do the trick BECAUSE of the FCS flight path stability attempt.
In ALT, from 265 or so KIAS, manually fly your A330 level D simulator to a 10 degree flight path angle at 35,000', at TOGA power if you like, and then take your hands off the SS. Watch the THS trim and sit back and enjoy (
) the ride, remain totally hands off at this point. (Monitor the FPV and SD Flight Control page for additional information.)
The THS will reach 13 ANU and AOA will reach 40+ hands-off. If you have the simulator Input Guidance capability selection at the instructor station, you can monitor AOA through-out on the VOR DME readout.
I'm afraid I do not have an A330 sim at my disposal to replicate his finding, but the way he describes it is exactly the way I would test this myself.
The behavior he witnessed however should not be called neutral stability. It is the definition of negative stability! The fact that the aircraft keeps trimming up silently well past the stall warning is extremely worrying.