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AF 447 Thread No. 12

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AF 447 Thread No. 12

Old 8th Sep 2014, 21:53
  #321 (permalink)  
 
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Mr Marnet-Cornus seemed to write again in a story telling what has been investigated and discussed, medias included.
He wrote that as a tribute to pilots' honor. But their survival would have saved their honor too.

Mr Marnet-Cornus seems to have misread our PPRuNe's threads :
- He seems to have missed what our specialist gums wrote about the inertial HUD and our following exchanges.

Why did French regulators, Air France heads, and important pilots' Unions like SNPL, UNAC, SNPNAC, SPIT, and younger Unions reject or at least forget the Klopfstein's HUD design ? (I have my idea ).


- He seems to have accepted that ACARS claim to be private informations , perhaps with Copyright, not to be used by pilots, Justice, investigations*, and pilots' feedback in training.

Not a word about HUD or not ECAM reported ACARS which should have saved the flight.

That report points other interesting questions but I feel it as partial. Dozy points the SNPL behind that report, but nothing shows that it is a SNPL report, it is Mr Marnet-Cornus' report.

*But the BEA did not follow that denegation

Last edited by roulishollandais; 8th Sep 2014 at 21:56. Reason: internet incident during operation
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Old 9th Sep 2014, 08:19
  #322 (permalink)  
 
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The 2 pilots of Habsheim accident were 2 instructors and freshly brewed in Toulouse A320 process. Concierge's job..
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Old 9th Sep 2014, 17:34
  #323 (permalink)  
 
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Apologies if this is re-hashing old ground, but AF447 was the subject of "Air Disasters" last week on the Smithsonian channel (I think it's what's known as "Mayday" elsewhere).

At any rate, assuming the presentation was reasonably accurate, it noted that the head pilot, after returning to the cockpit, was initially confused about what was going on, but eventually figured it out and started telling the Pilot Flight to push the nose down. Which raises the question: Did the PF ignore him, was it already too late (not enough altitude to recover), or was the aircraft in such a deep stall that it couldn't recover (or at least not recover without exceptional pilot skill)?

Not trying to start another argument, just trying to understand.
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Old 9th Sep 2014, 18:00
  #324 (permalink)  
 
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At any rate, assuming the presentation was reasonably accurate, it noted that the head pilot,
Captain Dubois
after returning to the cockpit, was initially confused about what was going on, but eventually figured it out and started telling the Pilot Flight to push the nose down.
Before the Captain returned to the flight deck, the First Officer, Mr Robert, had on a couple of occasions (per the CVR transcript available), advised the flying pilot, Mr Bonin, to "go down" (which I think he meant as lower the nose). The transcript and FDR suggest that Bonin never held the nose down long enough to make enough difference in terms of getting the AoA away from "stall" and toward "flying."
Did the PF ignore him,
The PF was task saturated and well behind the aircraft by the time Captain Dubois arrived. That much seems clear based on the report's findings. Some of the Captain's initial directions to Mr Bonin included help in keeping the wings level ... see the CVR transcript. This makes some sense if what he thought (initially) was the problem was the pilot needing to recover from an unusual attitude ... leveling the wings is usually the first step in that recovery to level flight ...
was it already too late (not enough altitude to recover), or was the aircraft in such a deep stall that it couldn't recover (or at least not recover without exceptional pilot skill)?
Hard to say, but probably true. That point in particular received pages and pages of treatment in the various AF 447 threads. You'll want to read the ones after the CVR transcript came out.

Given the AoA and the time Captain Dubois had to assess, and then try to correct, the flight condition when he arrived, every second that he was not actively directin recovery from stall inputs was a second lost to the eventual point of "no return." (At what point did he realize that the plane was stalled? Hard to say).
As CRM seems to have broken down between the other two pilots before he arrived, he was greeted with a confused situation that he tried to untangle ... and I'd say he ran out of time.

The poignant "it is not possible" (in Fr, impossible) remark points to him not believing something ... such as

This plane is stalled
and / or
These two geniuses were given a plane in straight and level flight and we are not flying straing level
and/ or
We are falling at what rate of descent????

There are any number of things that, having arrived on the flight deck and tried to sort out the problem, were so far beyond what he expected to find that it took some time/effort to overcome.

Time he didn't have.
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Old 9th Sep 2014, 19:30
  #325 (permalink)  
 
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Originally Posted by VNAV PATH View Post
The 2 pilots of Habsheim accident were 2 instructors and freshly brewed in Toulouse A320 process. Concierge's job..
Capt. Asseline was indeed senior Captain on AF's A320 programme - not so sure about the FO. But it had nothing to do with "concierges" or training - it had to do with poor planning, oversight and execution. In particular, AF never tried to verify Asseline's proposed flight plan with Airbus - if they had, then it would have become clear that Asseline was proposing a level of risk that Airbus's own test pilots would never allow (they would demonstrate Alpha tech at higher altitudes or perform low-level flypasts, but they would never combine the two, least of all with pax on board). In fact it's unknown if Asseline ever told AF ops exactly what he had in mind.

Originally Posted by tdracer View Post
was it already too late (not enough altitude to recover)
By the time the Captain worked out what had happened (when the PF stated words to the effect of 'I've been at max nose-up for some time now'), it was far too late.

@Winnerhofer - your last post is very dubious. For one thing, Bonin's wife was on the flight, but would have been back in the cabin. The idea of playing "musical chairs" with the flight crew is ludicrous. Bonin had been in the RHS since pushback - no need whatsoever to move his seat. I don't know where to start really...

Last edited by DozyWannabe; 9th Sep 2014 at 20:02.
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Old 9th Sep 2014, 20:17
  #326 (permalink)  
 
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@ Dozzy wanabee

CPT Asseline's first officer was in fact a Captain involved in the same AF A320 program. They were good friends what can explain some compliancy.. But they were overconfident in airplane behaviour. Good schoolboys..
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Old 9th Sep 2014, 20:30
  #327 (permalink)  
 
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Disagree. This isn't the place for discussing that - there was a thread which covered it a while ago here:
http://www.pprune.org/tech-log/528034-habsheim.html

I don't think it was overconfidence in the aircraft. Once in the air, it was a series of repeated failures (particularly on Asseline's part) to properly assess the risks involved in what they were doing.
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Old 9th Sep 2014, 22:26
  #328 (permalink)  
 
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Winnerhofer, I have no inside information.

My reply to tdracer was grounded in the information released to the public. If there is an omission there, I don't know how various bits of information will come to light. As you point out, court cases take a while and sometimes new info comes to light as part of the process.

In the case of AF 447, all I can say is "we shall see."
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Old 10th Sep 2014, 06:33
  #329 (permalink)  
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Hi Lonewolf_50;

There are some (who know their aerodynamics) who have done some work on this and who believe that the airplane could be recovered, even from quite low altitudes, (thicker air). The horizontal stabilizer was never fully stalled and the airplane demonstrated the ability to pitch down when ND stick was held those rare times in the ND position. As you know I've done this scenario in the simulator a number of times and the result is always the same; the elevator is effective, the stab returns from +13deg to a more normal -2deg or so which all helps to unload the wing, reduces the AoA and unstalls the wing. I wouldn't say they were done by 15000ft but perhaps by 8000ft or so, (which I have not tried; high up, it takes about 15000ft on avg to unstall the airplane - lower down, less).

I think they could have made it with room to spare. Also, I disagree with the use of the term "deep stall", which only applies to the BAC-111 and DC9 configurations. Discussed at length and not about to be re-argued here.
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Old 10th Sep 2014, 15:10
  #330 (permalink)  
 
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Recovery space

And more than that.. If the stab would have been manual trimmed to full ND position? how long would take to pitch the AC to a recovery AOA? Can be estimated, or at least guessed?

With the stabilizer not stalled, I suppose with a decent CFD soft it would be possible to estimate the pitching couple and pitching time too.. but again, demonstrating the fact that aircraft was recoverable until late in the event don't fit some very sensitive interests.
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Old 10th Sep 2014, 16:02
  #331 (permalink)  
 
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PJ2, glad to "see" you again.

No argument with your points.

My response was more about the space between the ears of the three pilots involved, and an attempt to address why (since they were in the "surprise mode" for quite a while during this upset) there was a point at which the Captain could have begun to issue the directions, or take the controls himself, to return the aircraft to "flying" versus "falling," overcome the inertia downwards with flight control inputs that would have arrested the descent (after overcoming the stall) before the aircraft reached the surface of the ocean. I recall the assessments and estimates you mention.

Since he did not have the benefit of knowing the scenario he was in as he entered the cockpit, the "run out of time" issue boils down to establishing inside his decision making ability "what is the aircraft's flight condition?" and then deciding "what shall I do/direct to get it back into control?"

I raised the point on how he was coaching Bonin into controlling his roll control since I think his initial assessment was that he was dealing with an unusual attitude recovery problem ... which he sort of was, but I have no idea if he ever arrived at the conclusion that "this sumbitch is stalled!" I'd guess he did at some point, but where was that? No idea.

Any decision point reached before the estimaged point of no return (your point on the denser air as they fell is well made) would need to be acted on by a correct application of anti-stall control inputs and a stall recovery.

I recall the long discussions on the point of no return, which you so kindly summarized concisely. My intent in the reply hopefully does not contradict anything from that discussion. If it does so, then my error is acknowledged, and maybe ti addressed tdrader's question clumsily. I suppose my "time he didn't have" contradicts the idea that if he'd reached the decision sooner that "it is stalled" and "Do This To Unstall The Aircraft!" were his instructions, then there should have been enough time to recover before impact with the surface.
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Old 10th Sep 2014, 19:39
  #332 (permalink)  
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Lonewolf_50;

I read but rarely enter something these days LW. The episode of the disappearing posts on R&N set my sails. However, I'm aware that others may be reading the AF447 work anew and I think a reminder of the significant effort put in by many, many contributors on "The AF447 Threads" is worth it as it is a veritable gold-mine of thinking and research if read with care, knowledge and an open mind.

I should point out for those looking to examine these threads the importance of the first post in almost all of the them. JT has done us all a favour and very kindly constructed and provided links to all the threads - I'll pick page one of the eleventh thread just as an example. One can search the entire PPRuNe archive using the simple search tools which JT and another prescient poster have provided us.

Insofar as "corrections" go, well, it's always a discussion and never a persuasion as far as I'm concerned because we weren't there an have only a tiny flashlight in a very large room that has tons of evidence upon which we simply cannot shine our little light. We can only make sense of the minute traces of the accident and take thinking as far as reasonableness and logic permit.

As far as court cases go and blame etc., I have absolutely no interest in it whatsoever. Though it understandably exists, that arena is a very foreign and hostile world to a flight safety person.
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Old 10th Sep 2014, 23:46
  #333 (permalink)  
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How can we work with imperfection?

The reality, I suggest, is that life is imperfect and we have to manage that regardless of the specifics of the day. Doesn't matter whether the topic be aeroplanes, cars, the state of one's health, wealth, or the attractive lass at the other end of the office, etc ..

Mitigation against the potentially adverse sequelae of such a reality involves a healthy and conservative mix of resources, knowledge, training, and practice, with a fortuitous portion of Lady Luck's smile.
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Old 11th Sep 2014, 02:10
  #334 (permalink)  
 
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Originally Posted by PJ2 View Post
I wouldn't say they were done by 15000ft but perhaps by 8000ft or so, (which I have not tried; high up, it takes about 15000ft on avg to unstall the airplane - lower down, less).
As it happens, around 9000ft is pretty much where they were at when the PF makes his "maxi nose up for some time" comment, and based on the assumption that the Captain did indeed figure out what had been happening from that (subtracting around 1000ft for the thought process to click), I think it's fair to say at that point it was too late.

Also, I disagree with the use of the term "deep stall", which only applies to the BAC-111 and DC9 configurations. Discussed at length and not about to be re-argued here.
Agreed (fervently).

Originally Posted by Winnerhofer View Post
Bernard Ziegler designed the Airbus to be pilot-proof.
No he did not. He headed the technical team that came up with the design, but the specification he had a hand in laying out was not due to his perception of piloting competence (or lack thereof), it was simply that the technology had reached a point where the control systems could be designed around the safe limits of the airframe. The intent was for the technology to *aid* pilots, not to patronise them (though BZ himself did have a couple of "foot-in-mouth" moments there).
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Old 11th Sep 2014, 04:03
  #335 (permalink)  
 
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why capt. Dubois exclaimed "It's impossible!"

@Lonewolf 50

The poignant "it is not possible" (in Fr, impossible) remark points to him not believing something ...
Capt. Dubois didn't comprehend why the aircraft was climbing while sidestick was forward

see below the situation dissected:

CVR // sidestick position // pitch attitude

2 h 12 min 32,4 Dubois: No you climb there // aft -8 deg // up 5 deg
2 h 12 min 32,8 Bonin: I’m climbing okay so we’re going down // full forward 16 deg //up 6 deg
2 h 12 min 34,2 Robert: You’re climbing // full forward 16 deg // up 8 deg
2 h 12 min 39,2 Bonin: okay we’re in TOGA // forward 10 deg // 0 deg
2 h 12 min 41,9 Bonin: On alti what do we have here? // forward 10 deg // down 3 deg
2 h 12 min 43,8 Dubois: (…) it’s impossible // aft -4 deg // down 3 deg

the reconstruction scene:
https://www.youtube.com/watch?v=XAom...ailpage#t=2475

It looks like a dejavu of XL888 crash.
.. flight control system automatically “trims” the THS to max nose up. The moment arm overcomes the elevator authority. The increased speed only serves to force the aircraft in a perpetum stall, like a dart plane, see pitch attitude graph

Last edited by _Phoenix_; 11th Sep 2014 at 04:28. Reason: repetition removed
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Old 11th Sep 2014, 07:18
  #336 (permalink)  
 
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Incompetence Meets Hubris
Incompetence
These accidents all have something in common: pilot incompetence
The pilots in these cases may have known their airplane fairly well.
They may have memorized their company’s operating manual and their SOPs.
But in all cases they did not understand some of the basics of flying an airplane.
There is always a Captain who has a real license to supervise the others with lesser licenses.
But on closer inspection what we are really saying is that a pilot who cannot legally take a friend for a ride can occupy a cockpit seat while the captain is back in First Class.
Automation and Hubris
Bernard Ziegler designed the Airbus to be pilot-proof.
He is a good pilot, and he noticed that many pilots are less skilled than himself.
In the interest of safety, he designed an airplane that could not be stalled.
But it has been known for thousands of years that hubris is followed by nemesis, that pride goeth before destruction, and an haughty spirit before a fall. (Proverbs, 16:18)
Hubris is arrogance before the gods.
The goddess Nemesis alone can see the fine line between doing the best work you can and believing that your work is somehow superior.
Cross the line and she is ruthless, finding your fatal flaw and using it to bring you down.
AF 447 was the fall of the hero.
Pilot carelessness led the airplane into a line of thunderstorms.
Supercooled water drops overwhelmed the pitot heaters, temporarily removing all three sources of airspeed information.
The autopilot dropped off.
The flight control computers switched from Normal to Alternate Law.
The airplane can be stalled in Alternate Law.
Human or robot, there is always a fatal flaw.
How can we work with imperfection?
AF447 | formercaptain.ca
Winnerhofer

I just love your contribution!

This should be glued up the wall of every manufacturer, administration and airline management.

Simply to daily remind them of these their deadliest sins.

And i consent with PJ2. It's quite revealing to see which contributions are "deleted" and which ones are deemed worthy to "remain".
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Old 11th Sep 2014, 19:09
  #337 (permalink)  
 
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High altitude stall practice

Captain left the flight deck in the hands of such low-time copilots.
Well, that's not how I would put it. Robert had more Airbus time than the other two combined.
Robert is the one that turned up the gain on the radar as soon as he got up there. The captain was negligent of monitoring the ITCZ activity and adjusting the radar gain and tilt accordingly.

Coffin Corner: The A330 with it's supercritical wing makes "coffin corner" a slightly different animal than it was in the 727 days—where Mach buffet was a real threat. The A330 on the other hand is performance limited more than MMO limited. But, pilots have not been educated on the characteristics of the modern airfoils where going critical Mach is much more difficult. Perhaps that's why Bonin apparently confused the shaking of the airplane due to low-speed stall with "some crazy speed" (Mach buffet perhaps). This is covered in more detail in my book "Understanding Air France 447."

The other very enlightening thing about doing stalls at FL300 is how completely useless the engines are in the recovery. Let's face it we're pretty close to full power at cruise anyway. Throwing the thrust levers up to TOGA doesn't do a damn thing (try it at cruise some time and watch the airspeed not move). That's something that practicing stalls in a jet plane at 5000 feet has definitely given many pilots the wrong impression of—since the engines work to fix the stall problem very nicely at that altitude. Hence 447's cry: "but we've got the engines, what's happening?" Some claim that the pilots didn't do any stall recovery. I contend they did exactly the stall recovery they were taught in their A320 checkout (the only time they practiced them) : apply TOGA power and minimize loss of altitude. Stalls are a pitch problem, not a power problem.
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Old 11th Sep 2014, 19:17
  #338 (permalink)  
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BPalmer

"Stalls are a pitch problem, not a power problem."

Stalls are an AoA problem, period.

Last edited by PJ2; 11th Sep 2014 at 22:40.
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Old 11th Sep 2014, 20:49
  #339 (permalink)  
 
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Originally Posted by _Phoenix_ View Post
.. flight control system automatically “trims” the THS to max nose up.
Only in response to sustained human input.

The moment arm overcomes the elevator authority. The increased speed only serves to force the aircraft in a perpetum stall, like a dart plane, see pitch attitude graph
No it doesn't. If you find the relevant sections of the original threads, it's made clear that the elevators *always* have sufficient authority to override the THS, with the caveat that they must be held in that position to do so. The reason the Pitch Attitude graph looks like it does is because there was no sustained effort on the part of either PF or PNF to get the elevators to nose down and hold them there.

Originally Posted by Bpalmer View Post
I contend they did exactly the stall recovery they were taught in their A320 checkout (the only time they practiced them) : apply TOGA power and minimize loss of altitude.
As you know, I've read your book and was very impressed by it - but I have to query your point here - at no point did any of the crew (including the Captain) acknowledge that they were stalled, verbally or otherwise. I contend that there was no procedure being followed - just almost random improvisation.
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Old 11th Sep 2014, 21:17
  #340 (permalink)  
 
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Originally Posted by PJ2 View Post
"Stalls are a pitch problem, not a power problem."

Stalls are an AoA problem, period.
Amen, deacon.

Mr Phoenix[/QUOTE] Capt. Dubois didn't comprehend why the aircraft was climbing while sidestick was forward [quote]
2 h 12 min 32,4 Dubois: No you climb there // aft -8 deg // up 5 deg
2 h 12 min 32,8 Bonin: I’m climbing okay so we’re going down // full forward 16 deg //up 6 deg
2 h 12 min 34,2 Robert: You’re climbing // full forward 16 deg // up 8 deg
2 h 12 min 39,2 Bonin: okay we’re in TOGA // forward 10 deg // 0 deg
2 h 12 min 41,9 Bonin: On alti what do we have here? // forward 10 deg // down 3 deg
2 h 12 min 43,8 Dubois: (…) it’s impossible // aft -4 deg // down 3 deg
I may recall incorrectly, but weren't they already falling by the time Captain Dubois arrived in the cockpit? I guess I need to go back to the thread and find the altitude traces to match up with your time data points there ... will get back to you when I have found it. What I recall is that around 1410 the event began, and they fell from FL 33-35 to the surface in the following four minutes. So, at 1412 the falling toward the sea surface, in a stall, was already in progress. However, I may have recalled that incorrectly.

Thanks.
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