Let me take this one...
Originally Posted by
Lyman
This is an anonymous forum ... you have worn only one disguise?
I know I have, because I know posting here is a privilege, not a right. And for what it's worth, the most respected posters on here have retained their original handles since they first signed up. Most forums I am aware of would have served you with an instant IP ban for doing what you've just admitted to.
The THS is inhibited >1.25, <.5. I mentioned .75. My Bad. I try attribution, and am "sowing pollution"?
Again, no -
only autotrim is inhibited from adding further
nose-up trim at greater than 1.25g. They didn't need nose-up trim, they needed nose-down trim. The aircraft didn't reach a g-loading low enough to inhibit autotrim completely (0.6 > 0.5), so autotrim was never offline in the direction the THS needed to go. Furthermore, even if the g-loadings are beyond the limits of autotrim functionality, manual trim is always available.
Now - either you've missed my previous post explaining this or ignored it, but I can assure you that I will raise it with the mods if you post the same incorrect information on this technical thread again.
"TRIMMABLE" HORIZONTAL STABILISER. That is not a correct designation, in design, practice, and Training. In fact, it is opposite what is trained.
What is trained is to leave the wheel alone, Only in DIRECT LAW challenge the virginity of the wheel and assault her with your palm.
Again incorrect. Svarin, back in a previous thread, claimed that his airline vehemently discouraged use of the manual trim wheel at any time other than a switch to Direct Law. PJ2 said that his airline left use of the manual trim wheel to the pilot's discretion, and indeed trained him quite extensively on it's use. So if we are to take that information at face value, then it appears to be at the discretion of the airlines as to how the manual trim wheel is to be approached.
As of this moment, we do not know what Air France's policy was or is regarding the manual trim wheel, so to state as fact that the pilots were trained to leave it alone is a falsehood, because the only thing we know for sure is that we don't know. (h/t Socrates).
Responding to PF NOSE UP?
Almost certainly.
Or to gain loading for the airframe when it was less than 1g?
Possible, but unlikely.
I doubt it.
Later, it went 'Dormant' at NOSE UP all the way down.
No, it stayed there because there was neither a nose-down SS input deflection for a sufficient period of time, nor was there any attempt to manually change the trim.
Posit. The a/c was UPSET at the loss of a/p, and LOC happened soon after ~ . With LOSS OF CONTROL, a design that trims in elevator for its retention when maneuvering is the order of the day? Hmmm.....
Sorry - that doesn't wash. Far more likely is an overcontrol response to correct the slight wing-drop at FMS disconnect, followed by PIO as the PF consistently overcorrects, possibly tensing up and inducing the nose-up attitude we see. Look at the FDR traces - now, admittedly I'm working from memory here, but most upset recovery procedures require progressive and sustained control inputs opposite the direction of the upset, until stable flight is resumed (this, incidentally, is why the 737 rudder-reversal failure mode was so deadly, with pilots thinking they were putting in correcting rudder when in fact they were controlling in the direction of the upset and inducing a spiral dive). The AF447 traces show the lateral SS movements going from stop to stop repeatedly over the space of a few seconds at most, classic PIO. Judging by the PF's remarks on the CVR, he seems primarily concerned with lateral control and unaware that he is making pitch demands at the same time - only the PNF seems to notice this ("you're going up - go down"), and reminds the PF to touch the lateral controls as gently as possible.
Above all, the magnitude of the inputs made is more appropriate for batting a Pitts around in VFR conditions at a couple of thousand feet, certainly not appropriate for a widebody at cruise in IMC at night.
The THS, as it moves, changes the flight characteristics of the airframe, it changes the ANGLE OF INCIDENCE of the aircraft, as well as its PITCH.
This is why ANGLE OF INCIDENCE is considered separate from AoA, for it is a critical component of AIRCRAFT ATTITUDE.
Until one separates these two concepts AOI, AOA, the manner of control cannot be explained.
Yes it can, and it was explained by several people not long after the black boxes had revealed their first secrets in the lab. In normal flight, autotrim trims the aircraft to maintain a g-loading (in most cases). In the case of Alternate Law with no protections, the autotrim will follow any demand made by the pilot based on the assumption that the pilot knows what he or she is doing - this feature of the design is specifically to support ease of operations in abnormal circumstances. If the pilot does not feel that the autotrim is behaving as they desire it is a simple matter of moving the trim wheel to the desired position and the aircraft will attempt to stabilise around the manually set trim, with the autotrim taking over again from there except in the case of Direct Law or Mech Reversion.
@PJ2 - I completely and unreservedly accept what you are saying and agree totally. However, what bothers me is the knowledge that some journalists are known to either paraphrase or report verbatim some of the things that are posted on here. The BEA and Airbus have spent years trying to overcome the largely undeserved reputation they garnered by the number that Michel Asseline and his enablers in the press did on them, and what worries me is that I'll open the paper one day to find one of Bearfoil/Lyman/Will Fraser's more lurid assertions reprinted as fact in an environment where the general public are more inclined to take such things at face value (which is why we still have people saying that the A320 "overrode the pilot" and hit the trees "because it thought it was landing", and other such nonsense).