Originally posted by Ian W
Perhaps with elevators alone and a THS neutral the aircraft would have dropped its nose, then (had PF kept NU) after getting flying speed its nose would come back up. Perhaps PF was expecting this nose drop 'nodding' behavior? Its what would happen in a lot of gliders and light aircraft and he was glider qualified. The lack of this nose drop possibly convinced PF that the aircraft could not be in a stall.
Response from JCJeant
Some answers from Troadec (BEA director)
Quote:
Question: there are a lot of airplanes which, when they stall, pitch nose-down including when they have stalled and their last command was to pitch up. This is apparently a phenomenon that many glider or flying school pilots are familiar with. Yet, here we can see that this phenomenon did not occur, that the airplane fell straight while remaining nose-up. Is this a stall mode that is normal or expected?
Jean-Paul Troadec: what was said, is that the airplane stalled from the pilot’s nose-up input. So, mostly the pilot’s inputs were to pitch nose-up, which maintained the stall.
Question: is the way the airplane stalled, that is to say straight while remaining nose-up and not nose-down, is it normal or typical or expected. Let’s say that a lot of airplanes pitch nose-down when they stall.
Jean-Paul Troadec: it’s a point where… Well, I cannot answer your question and say if it is normal or not. It is the situation of this airplane which is perfectly in accordance with the regulations and which was certified.
Thank you for this response. My query took this just a little further.
Had the THS been at a more normal cruise setting and not fully NU, would the PF been able to hold the nose up during the established stall - with the aircraft dropping at 11,000 fpm (over 100 kts vertical component) - using elevators alone? Or, would the aircraft nose have dropped despite the NU elevators? Surely someone must have calculated this?