Dozy,
Just how much of the range that is possible of NU on the THS would be used in a normal cruising flight at altitude ? You have flown the sim ( with any limitations that may or may not have had). Your recent experience exceeds mine by several decades. (Earlier aircraft types used to cruise with the trim close to the middle, more than a notch or two, up or down would be uncommon.) "Almost fully NU..." would have made "my oil pressure warning light / excess THS" illuminate, (had it been fitted). Perhaps this would still have been too late for the Captain. But there were two other pilots... The CVR print-out can give no indication of just how "10,000 ft." was said, as the first mention of direction of travel. |
The concept of 'limiting' normal THS movement was proposed after the PGF crash, but seemed to go nowhere. I mooted a 'push to over-ride' button set at an appropriate value.
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Originally Posted by PJ2
I assume you mean the position of the THS
Except from the FDR data, the BEA report is absolutely empty on the matter. To be told that the THS moved from 3 to 13 degrees in 1 minute or that the THS moved accordingly to the stick inputs and as designed is vastly insufficient. The "influence of the THS" argument has been demonstrated as a non-starter. Owain Glyndwr made very interesting comments which should have been already part of a final report. The BEA had all the necessary tools to elaborate further on the subject.
Why not trimming in a stall ? You’ve been asked the question. You did not reply ... ? |
What does it take to get out of hibernation?
Originally Posted by PJ2
(Post 7439948)
CONF iture;
The "influence of the THS" argument has been demonstrated as a non-starter. The aerodynamic argument has been examined by Owain Glyndwr to which reference has been made before. The aircraft remained in the stall because of the predominantly NU stick position held in by the PF, and not due to the position of the THS. You're not saying that the HS has no contribution to the NU are you? But it reads that way. The A/C remained in stall because of the sum of the effects of ALL the aerodynamic contributing factors to a prolonged NU, of which HS is part of. The NU stick drove the automatic move of the HS to MAX NU. If the NU stick would have had no effect on the THS - if the HS would stop moving at STALL condition detection - that would have removed the HS from the contributor factors. But that was not the case. CONF iture is absolutely right that this should be documented well by any analysis, or technical report. |
Originally Posted by CONF iture
Except from the FDR data, the BEA report is absolutely empty on the matter.
To be told that the THS moved from 3 to 13 degrees in 1 minute or that the THS moved accordingly to the stick inputs and as designed is vastly insufficient To answer your question, though rather obliquely, I defer to another part of the same post where I pointed out that Airbus expected its aircraft to be flown by properly trained and competent pilots. I know this doesn't make anything right, but part of being a competent pilot is to have a thorough knowledge of the aircraft flight control substructure, which includes the level of automation available from Normal Law to the fallback positions, i.e. Alternate + colors and Direct Law. Likewise, I am well aware that the attributes of the aircraft when in Normal Law have been espoused ad infinitum, but that's the "gilding on the Lilly", and as you know there are "man traps" for the unwary when the automation level degrades, and AF447 clearly revealed those traps, i.e. the Stall Warning NCD switch off, and to a lesser extent the Auto Trim action when in Alternate 2B Law. The FC training for the A350 will be different, and starting on the ground floor will IMHO enhance the basic understanding of the aircraft flight control structures, and maybe pilots will once more get to respect and understand the advantages and limitations of each layer of automation that gets added. You claim that the crew of AF447 were badly served, but I venture that poor CRM along with some unfathomable actions by the PF provided none of the service expected by the aircraft, nor the other souls onboard that night. I respect your right as an A330 pilot to question the data and confusing manner in which the crew became aware [or in this case not aware] of their situation. Though, I'm inclined to ask why the situation that developed at A/P off wasn't resolved as UAS by them? They knew:-
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Thank you mm43 and PJ2.
I shall sit back for a while, as well, but noted the recent article about training for the A350 or whatever the thing is called. Emphasis upon flying the basic FBW system, then adding all the neat A/P functions and normal law "protections". |
Airbus made a good change in their initial training with the manual flying prior to blending in automation. Hopefully that won't be the end of it because we all know if you don't practice it on a regular basis the skills gradually deteriorate.
SOP's allowing pilots to handfly when conditions are right is the only way they can maintain those skills. It is in everybody's best interest to let them retain these skills. |
from PJ2:
....It was "normal" after a while and flying a raw-data, no FDs, manual thrust ILS even in clear weather slowly became a real challenge. That, quite frankly, is not and never was, a good thing. Autoflight's a simple bread-and-butter assistant, not one's keeper. As I have oft-stated, I encouraged the fighter jocks I flew with/helped learn to use the A/P to reduce workload when things got very BZ. With only one human in the jet, the A/P really helped during a WX abort/diversion to new field or an alternate approach. The big difference between our use of the A/P was that it was the exception and not the rule. Sure, we used altitude hold and heading hold when crossing the pond or flying st-and-level for more than 10 or 15 minutes. But we never used it from 500 feet AGL after takeoff until final approach. Seems to me that with a crew of two or more that "the other guy" can handle the admin and the pilot can simply fly the profile best he/she can. I have a hard time understanding why the human pilot cannot descend/turn/climb within a few knots or a degree or two heading/pitch. My only experience in a "heavy" was a joyride in the 'vaark. Sucker weighed 3 times what my Viper did. That being said, I flew a st-in and landed the sucker all by myself after about 20 minutes of "stick time". Once getting it lined up and trimmed, holding within 2 knots and a half degree of required pitch for the descent was a straightforward exercise. It was like on a wire. Very comfortable. And my B747 captain buddy said the same thing about that beast. And be advised that in the T-33 with the J-8 attitude indicator that we made pitch corrections for a GCA or ILS approach using the thin white line on the "horizon" line - figure about a half degree of pitch or less. The SLUF had a "flight director" to cue you when intercepting the ILS glide path and centerline. The Viper was pure manual, and you can see my emergency landing HUD here to see how we did it ( Q-time required): http://www.sluf.org/warbirds/lef-landing.m4v For those HUD naysayers, I can guarantee that a raw nugget made beautiful approaches first time. That flight path marker didn't depend upon any air data - it was pure inertail vector, and was easy the "lead" the turn or pull. |
Originally Posted by PJ2
(Post 7443743)
airtren, CONF iture;
Thank you for your observations and critique of my last. airtren, re your comment, "You're not saying that the HS has no contribution to the NU are you? But it reads that way." No, I am not saying that the THS "has no contribution" to the NU attitude. Now that I review it, you are right that the statement, in and of itself, wasn't nuanced as I have in the past and can read that way. But the contribution of the THS to the sustaining of the stall has been thoroughly discussed even if it has not been thus in the BEA Final Report, and my own views on the contribution of the THS are both expressed and known as are my views on why the stall continued instead of being recovered from. ..... I made the observation that overall, the behaviour and contribution to the stall of the THS has been thoroughly examined and the statement made on such contribution thus, (bolding is in the original) by someone who really knows what they're talking about, supports the view that the NU stick and not the THS were the critical factors: Even though you may have NO acrobatic or fighter pilot training, and thus direct and repeated experience with entering and exiting stalls, I would ask nevertheless your opinion based on your pilot expertise: Question: If you were the AF 447 Captain, and had understood at the very moment of re-entering the cockpit, the Stall state, and the Cause for it, the extremely short amount of time left for a successful recovery, and had known what it takes to exit the Stall and recover the A/C, what would you have ordered the PF to do? 1. move stick ND ASAP and move THS manually to NEUTRAL or MAX ND ASAP or 2. move stick ND ASAP and keep THS to MAX NU? |
Originally Posted by airtren
(Post 7445756)
1. move stick ND ASAP and move THS manually to NEUTRAL or MAX ND ASAP
or 2. move stick ND ASAP and keep THS to MAX NU? 3. Move stick ND and allow autotrim to move the THS back to neutral. Possibly a little slower than option 1, but not by a great deal. In fact option 2 is impossible. Pushing the stick ND will cause the THS to follow suit in Alternate Law. |
No, I am not missing anything!
But you're missing: I. that both 1 and 2 involve Manual Control action onto the THS from the pilot. II. "the extremely short amount of time left for a successful recovery" from my post. I know you're not a pilot... A pilot will do everything in his direct power, to speed up the action on control surfaces, knowing that time is NOT on his, his crew, and his passengers side. Although I have to thank you for making my point by answering indirectly my question by indicating option 1 as the fastest..... as a matter of courtesy, your abstaining from interfering with my question directed to PJ2, by obstructing it, or answering it, and letting PJ2 answer, would be also appreciated.
Originally Posted by DozyWannabe
(Post 7445961)
You're missing option 3:
3. Move stick ND and allow autotrim to move the THS back to neutral. Possibly a little slower than option 1, but not by a great deal. In fact option 2 is impossible. Pushing the stick ND will cause the THS to follow suit in Alternate Law. |
Originally Posted by myself
The THS behavior and influence in this accident must be detailed, not hidden.
Not much in the FCOM and nothing more in the BEA reports - Actually a pdf research on THS shows how unpopular those 3 lettres are to the BEA ...
Originally Posted by PJ2
the ECAM drills were not done when the event occurred
It took 35 sec (or is it 15 ?) to move the thrust levers, that's all. |
Originally Posted by DozyWannabe
In fact option 2 is impossible. Pushing the stick ND will cause the THS to follow suit in Alternate Law.
What did stop its operation ? |
Except to say there is no evidence presented in favor of, or in disagreement with, the above, I would suggest that's essentially what happened.
The Captain's comments were initially leaked, "This is STALL, get the Nose DOWN". That was reported in the Press, and one can draw their own conclusion. By its absence, virtually all here have concluded it did not happen. Given the fact that the Captain entered the cockpit when he did, having heard Stall, and seen the cues described above, it would be incumbent upon BEA to provide the CVR audio surrounding this entry into the flight deck. Instead, nothing.... I do not know if the CVR even exists, or if the chronology was assembled out of whole cloth. Were I family, or friend, I would make it my mission to acquire the last words, if only to be with these men in their last moments. Given the stakes at hand, one tends to be suspicious even of saints, let alone an agency with a history that suggests scepticism might be in order.... The chronology above is hindsight, as warned, but suggests that with all the cues and conditions present, the Captain and his two F/O's were other than qualified. And that is not the case.....Something is missing, literally. |
Originally Posted by Lyman
Except to say there is no evidence presented in favor of, or in disagreement with, the above, I would suggest that's essentially what happened.
The Captain's comments were initially leaked, "This is STALL, get the Nose DOWN". That was reported in the Press, and one can draw their own conclusion. By its absence, virtually all here have concluded it did not happen. Given the fact that the Captain entered the cockpit when he did, having heard Stall, and seen the cues described above, it would be incumbent upon BEA to provide the CVR audio surrounding this entry into the flight deck. Instead, nothing.... I do not know if the CVR even exists, or if the chronology was assembled out of whole cloth. Were I family, or friend, I would make it my mission to acquire the last words, if only to be with these men in their last moments. Given the stakes at hand, one tends to be suspicious even of saints, let alone an agency with a history that suggests scepticism might be in order.... The chronology above is hindsight, as warned, but suggests that with all the cues and conditions present, the Captain and his two F/O's were other than qualified. And that is not the case.....Something is missing, literally. By now it is obvious that something IS missing, what that is may never come out. Que Sera Sera |
@TTex600, with the greatest respect:
Lyman, the problem you face is simply that no one still participating in these discussions is interested in why the event occurred. Most everyone is either: defending a position, or defending a perception, or pontificating to hear themselves talk. By now it is obvious that something IS missing, what that is may never come out. Que Sera Sera Was this so-called leak accurate? Inquiring minds will never stop inquiring. |
Tex
Of course. I have no real position re: what, where, why.... From the outset, I have faulted BEA for not providing the evidence they supposedly possess; their data is based on something not in the record. Instead of looking at that, most people do dig in, I hope I am not one, for as above, I do not KNOW. The report is unacceptable. 1. In reporting some of the CVR, BEA leave open the suspicion that Airbus is at fault. 2. The suspicion exists also that the pilots are at fault. 3. The "Conclusion" (one of) exists that there is a blend of responsibility for this tragedy. Without a jaundiced eye, BEA escape their responsibility, and play the politician. Que sera? Strange attitude from a line pilot... The only hope of getting to the evidence is to hope that the CVR still exists, or certifiable transcripts... This can be done via FOIA if/when the FAA get access to the record... Til then, my hope is that people do not give up, NO MATTER THE INTENT. |
Originally Posted by Organfreak
@TTex600, with the greatest respect:
Quote: Lyman, the problem you face is simply that no one still participating in these discussions is interested in why the event occurred. Most everyone is either: defending a position, or defending a perception, or pontificating to hear themselves talk. By now it is obvious that something IS missing, what that is may never come out. Que Sera Sera As it happens, I agree, for once, with Lyman on this point, and am still interested in what may be missing, not that we'll ever find out! Was this so-called leak accurate? Inquiring minds will never stop inquiring. |
"The transcribed CVR indicates that standard ECAM discipline was not accomplished. Without announcement or communication to the PNF, a sustained pitch-up occurred, even as the PNF attempted to do the ECAM drills. There was no announcement of the ECAM messages from the PF, and their subsequent response was done in an undisciplined, halting manner that did not initiate and did not complete as per SOPs*. There was no evidence of CRM."
You are missing the evidence to support your conclusion. The CVR is not complete, we do not know what is missing.... Speculation, over time, morphs into gospel... As expected, BEA succeeds. |
Originally Posted by PJ2
(Post 7447253)
Dozy;
It is courteous and respectful to permit the person addressed in a communication to respond first. Thank you.
Originally Posted by Lyman
(Post 7447288)
The Captain's comments were initially leaked, "This is STALL, get the Nose DOWN". That was reported in the Press, and one can draw their own conclusion.
I'm not saying that there haven't been occasions where press action has brought things to light in a positive way (I'm thinking particularly of the expose on the MD/FAA "Gentlemens' Agreement" regarding the DC-10 cargo door, and the Seattle PI's dogged pursuit of the 737 rudder problems), but on balance I'd say I'm inclined to take isolated press reports with a hefty dose of salt. |
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