Originally Posted by
Smilin_Ed
Of course I want the aircraft to respond to control inputs but I wouldn't want it to change the trim. That is a very basic thing when flying in turbulence. In this case, it followed what was clearly an erroneous input by the PNF and trimmed them up into a stall, a no-no taught to every student pilot.
Hi Ed,
Is that because you can't see any instance when it would be useful or because it goes against the methods you were taught flying aircraft with more "conventional" controls?
IMO (for what that's worth) there's nothing wrong with the autotrim setup as long as the way it works is taught properly. If you look at the traces the trim moves minimally under automatic control. What caused it to deviate so strongly was a series of inputs that trended towards nose-up, the majority of which were around half the stick's rearward travel limit, that were sustained for the best part of 45 seconds. What caused it to continue the movement to the stops was a full nose-up deflection that lasted between a further 30-40 seconds - that's more than 1 minute and 20 seconds of nose-up input at a deflection that ranges from halfway to the stops - at cruise level!
The trim doesn't move in any noticeable way as long as the inputs are relevant to the flight regime. The PNF notices that the PF's lateral inputs seem to be extreme, and admonishes his counterpart. He then further upbraids the PF for commanding a climb when it is unnecessary. This is why the BEA recommend training for manual aircraft handling at altitude, because in this case the sidestick inputs are repeatedly way beyond what is reasonable at that altitude and airspeed.
Originally Posted by
gums
Thank you, Wozzo, very interesting press release. Seems that some BEA investigators are concerned about some of the same things that several here are, as well. And it's not all strictly pilot error or strictly aircraft system design.
Well, the press release appears to be in response to the articles that appeared to have sources with in AF who are clearly not happy about the stall warning situation. Whether that relates to a well-researched hypothesis, or whether it is an attempt to muddy the waters in anticipation of the division of responsibility in the coming criminal and civil litigation it is impossible to say.
- An AoA indicator is "nice" to have
And it is indeed in the recommendations that have been agreed thus far.
seems the 'bus has enough confusing displays as it is.
Confusing how? I'd say they're pretty well laid out for mid-80s technology!
- Ask the above pilots if the AoA sensors ( vanes or cones) worked below 60 knots. Even if the AF447 suckers were bouncing around a bit due to an extreme AoA, I'll bet they showed a high AoA, and were not flipping back and forth from plus 30 deg to minus 30 degrees.
Well here's your traces (corrected values and raw) :
Looks pretty spiky to me after 02:11:45...
"We're going down, sir"
"O.K., command the plane to go up"
" I am doing that, sir, but she keeps on descending"
With all due respect, they never said anything even close to that...