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AF 447 Thread No. 12

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AF 447 Thread No. 12

Old 18th Jun 2014, 20:59
  #121 (permalink)  
 
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Gums,

Both Dozy and PJ2 (a former A-330 pilot) did recovery exercises in the SIM. Going back to the original AAF447 Thread #9, this is what PJ2 had to say about one of his recovery attempts:
Post 168 AF447 Thread #9
In the sim exercises, for recovery the SS was held full nose-down from the beginning of the stall warning at about FL360 until the wing was unstalled at about FL250, about 40 seconds total time, with a maximum achievable ND pitch of about -12 deg with an average of -10deg. The thrust levers were in the CLB detent and the THS was initially at 13.6deg and was returning to the normal cruise setting.
With the FPV symbol available, the FPA could be observed just above initially at -40deg, (pitch -10deg).

It began to move, initially very slowly up, about 15 seconds after full ND SS;

- at 29 seconds after full ND SS, the FPA had moved from -40deg, (pitch at -11) to -25deg, (same pitch);

- in the next 5 seconds it moved from -25 to -15, (FL257);

- at 38 seconds after full ND SS the FPA was -9deg, (pitch -5deg) with the wing unstalled and the CAS at 255kts.
One other thing that I think is important from a AF447 historical perspective that PJ2 pointed out discusses "Startled" in a collection of posts:

"Startled" is an invented, psychobabble notion created by non-pilots/non-aviation people in an industry that has been dealing with transport emergencies and abnormals and improving on checklist design, system design and crew performance for same, for over fifty years. Why suddenly does the notion of being "startled" in an airliner cockpit have the currency that it does instead of being examined for what it is actually saying?
Is the trend towards relatively low cockpit experience with commensurate reducing skill standards in combination with highly-automated aircraft technologies where a pilot can now be overwhelmed by anything just beyond training and experience, finding new expressions in terms like "startled"?
If "startled" is the new metric when examining human factors in aircraft accidents then there are some serious questions to be asked of those processes upstream from putting crews into transport cockpits who can handle the profession and the job.

And finally,

I am unconvinced of "startle" - everyone is 'startled' to begin with - I have experienced a massive hydraulic failure on the same equipment and yes, it was initially startling but one reverts to training and deals with the ECAM accordingly. I have no idea why it came apart so swiftly and we'll never know. All we can do is re-emphasize what would have saved this airplane, this crew and these passengers, because this was not an emergency and there was no requirement to do anything other than ensure the airplane was stable while the ECAM drill was done according to Airbus SOPs.
I like PJ2's thoughts here, in effect, everyone is startled when something unexpected happens, it's what you do or don't do after being startled that determines the outcome.

A last point: There is a difference between stall prevention, given the warnings and what is done to recover from an actual stall. This Airbus presentation discusses these differences on pages 11 & 12:

http://fucampagne2008.u.f.f.unblog.f...lprocedure.pdf

Cheers!
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Old 18th Jun 2014, 22:41
  #122 (permalink)  
 
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Startled or Man with hammer syndrome

Bonin was convinced he needed to pull the stick back all the time.
So convinced he ignored the nose up attitude, decaying airspeed, stall warnings, alarms, incursion into other FL and ignored Robert repeatedly telling him to descend. Bonin clearly verbalizes that he was stick back all along which tells us that it was a conscious decision. Not only was Bonin behind his airplane he was ignoring every fact being given to him. Startled is an over simplification of Bonin's mental state and warrants further consideration along with all the other failings. I leave it to the pysch experts to explain his fixation with stick back e.g. man with hammer syndrome, confirmation bias.

02:13:40 (Robert) Remonte... remonte... remonte... remonte...
Climb... climb... climb... climb...

02:13:40 (Bonin) Mais je suis fond cabrer depuis tout l'heure!
But I've had the stick back the whole time!

At last, Bonin tells the others the crucial fact whose import he has so grievously failed to understand himself.

02:13:42 (Captain) Non, non, non... Ne remonte pas... non, non.
No, no, no... Don't climb... no, no.

02:13:43 (Robert) Alors descends... Alors, donne-moi les commandes... moi les commandes!
Descend, then... Give me the controls... Give me the controls!

Last edited by xcitation; 18th Jun 2014 at 23:37.
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Old 18th Jun 2014, 23:11
  #123 (permalink)  
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Chaps,

Tech Log seeks to discuss and debate technical issues - which, obviously, includes the human aspects of technical subjects.

Sometimes, some of us have very strong views on this and that.

However, we don't need to venture into personal commentary of an adverse nature where that is not materially pertinent to the underlying discussion - where this might be permitted, it will need to be justified objectively as being pertinent.

As always, the desired aim is to play the ball, not the players.
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Old 19th Jun 2014, 00:50
  #124 (permalink)  
 
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Originally Posted by xcitation View Post
Was it a Titanic belief in the un-stallable nature of the airbus that the warning must be a glitch not even worthy of discussion?
A slight possibility exists, but I very much doubt it - for one thing, the fact that the aircraft can stall when in a degraded flight law is down in black and white in both training and ops materials that I know of. Also, the crews in the other similar incidents I mentioned earlier weren't flying FBW Airbus types, and the PF in those cases disregarded not only the Stall Warning and stick-shaker, but also their crewmates telling them they were in a stall!

@Turbine D:

I have a lot of respect for PJ2, and agree with the vast majority of what he writes. However what bothers me about writing off the consequences of what has recently been termed "startle response" as a
Originally Posted by PJ2
psychobabble notion created by non-pilots/non-aviation people
is that while the industry has - as he said - been dealing with scenarios such as this for a very long time, the fact remains that there is always room for improvement.

I was enjoying one of my periodic re-reads of "Fate Is The Hunter" the other week, and there was an embryonic version of the subject even then. Gann refers to it using the concepts of "fright" and "fear":

Fear and fright are two different things, the emotion of true fear requiring time for culture and preferably a period of helpless inactivity. Then fear breeds upon itself because it is a hermaphrodite capable of endless reproduction. Fear is a contagious disease, spreading from its first victim to others in the vicinity until it is powerful enough to take charge of a group, in which event it becomes panic.
Fear is the afterbirth of reason and calculation. It takes time to recuperate from fear.

Fright is only the percussion of fear. It snaps rather than rumbles and its explosion is instantaneous. Likewise, fright is self-destructive, being more of an instinctive physical reaction than it is an emotion. It hits, explodes, and may be gone as quickly, if it does not have time to ignite the keg of fear
(Emphasis mine)

If no less a legend of aviation than Gann had a handle on it many decades ago, then I'd venture to suggest not just that there may well be something in it, but that there may be some mileage in studying the effect properly.

What bugs me about how a lot of the hearsay around this case has gone down is that there's been a worrying groundswell of dismissive opinions from some quarters along the lines of: "Well, he was low-hours/automation-dependent/a 'magenta child', so he didn't really know how to fly". Which raises the worrying assumption on the part of people making such comments that they're dead certain that it would never happen to them. Part of the reason I've been banging on about the other incidents where captains with in excess of ten thousand hours and/or with a successful military career behind them have ended up doing more-or-less exactly the same thing is because people making those assumptions, in the face of these contrary facts, frankly scare the bejeezus out of me!
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Old 19th Jun 2014, 01:07
  #125 (permalink)  
 
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@Machinbird,
Pardon. " As we know, the transcription of the acronym "PIO" has been modified and is still unfixed so long the solutions to avoid and recover from a variety of "oscillations" are still to fix and understand better. My propositions are leading too far of common definitions of theory of systems. I don't want to contest them (instability, gain, human operator transfer function). I have to write that clearer.
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Old 19th Jun 2014, 04:22
  #126 (permalink)  
 
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AF447 discussion deuce

Well, JT, I think we need to let this thead go on. Maybe re-label it and start over with existing posts, and that's your call.

There are a lot of techniques and personal war stories and lessons-learned and such for folks to learn from, huh?

We have had a diverse group of pilots and engineers here for almost 5 years. As a "light" pilot with an engineering degree, I was accepted by this current group to offer my lessons from an early FBW jet and to comment about other aspects of the aviation mistress we all served.

Seems all of us want/desire to help prevent accidents if all crews knew the data from the previous episodes to include crew techniques/actions, past problems of mechanical or electronic nature, and the beat goes on.

I vote to keep the thread going, but maybe re-label it and move to another forum if we have to.

On the road now to high country, owe some decent responses to some posts and will try to keep up with my morse code telegraph line from cabin to 'net connection. Carrier pigeons won't stay here, and chipmunks are unreliable.
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Old 19th Jun 2014, 04:55
  #127 (permalink)  
 
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Xcitation makes a telling observation about the progression of events in the AF447 cockpit.
IMHO the most perplexing of all the holes in the swiss cheese is the total absence of discussion given to the stall warnings by all 3 pilots. Was it a Titanic belief in the un-stallable nature of the airbus that the warning must be a glitch not even worthy of discussion?
Have you ever had a wasp in your vehicle as you were driving? Darned distracting, wasn't it? In fact, this type hazard is so distracting that drivers experience a very high frequency of traffic accidents during these events because they cannot properly prioritize hazards and give their full attention to driving.

I have a personal theory (that is only a theory) that all 3 pilots were rapidly sent past their maximum sensory processing thresholds and thus they were filtering out all background noises. The development of this process in all 3 crewmembers seems to have followed a triggering sequence.

Bonin started the sequence by encountering roll PIO which dominated his full attention in a manner similar to the wasp phenomena that I mentioned at the beginning. His control of the aircraft was clearly deficient.

Bonin's flying greatly concerned Robert but since he felt constrained by the Captain's briefing, he did not give relief to his concerns by assuming control, but instead monitored the gent (big wasp) in the other seat who was effectively trying to kill him at the moment and concentrated on calling the Captain.

By the time Captain Dubois arrived on the flight deck, the situation had progressed to the point that the aircraft was not properly following the controls. Both the copilots loudly made exclamations that the aircraft was not under control. In effect, he had walked into a cockpit full of wasps. Apparently nothing in his background had prepared him for unraveling such a mess.

I know that things are never supposed to get this far out of hand in an airline cockpit, but it happened in real life. A triggering event followed by a triggered sequence is one way to explain how something like AF447 happened.

They never mentally heard the stall warning because there was no relief from the mental pressure of the event. The hazard kept increasing as the altitude unwound. There was no clear AHA moment.
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Old 19th Jun 2014, 05:23
  #128 (permalink)  
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gums,

The thread is far too interesting not to let it run its course ....
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Old 19th Jun 2014, 11:36
  #129 (permalink)  
 
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Did the Cpt Dubois experienced the SW or "inverted SW" only ?

By the time Captain Dubois arrived on the flight deck, the situation had progressed to the point that the aircraft was not properly following the controls. Both the copilots loudly made exclamations that the aircraft was not under control. In effect, he had walked into a cockpit full of wasps. Apparently nothing in his background had prepared him for unraveling such a mess.

And there is no certainty that even the SW was still on at the moment of his instrument scan.
And of course nobody want even to try to establish if at that time a determined (or yes, desperately) maneuver would allow recovery (no, not only full fwd stick , but rather a forced direct law + manual trim full ND at structural limit, even if that would made things to fly in the cabin, followed by a recovery at the g limit again).
After all many "impossible" situations were saved by pilots performing unstandard and untrained maneuvers. But yes - in a good situational awareness, which was not the case of AF447 - this plane set trap after trap to his crew, and of course they are only to be blamed for falling in ...
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Old 19th Jun 2014, 15:20
  #130 (permalink)  
 
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Did the Cpt Dubois experienced the SW or "inverted SW" only ?
The answer of course is that he only heard the inverted Stall Warning.The stall warningstopped as he entered the cockpit because the airspeed was too low for it to make sense (NCD).

Even if he heard it, it didn't make good sense to him either. It went into the too hard to understand right now category.
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Old 19th Jun 2014, 16:24
  #131 (permalink)  
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Dozy, re:

However what bothers me about writing off the consequences of what has recently been termed "startle response" as a
Quote:
Originally Posted by PJ2
psychobabble notion created by non-pilots/non-aviation people

is that while the industry has - as he said - been dealing with scenarios such as this for a very long time, the fact remains that there is always room for improvement.
I was well aware of fear/fright factors from the day one of my private licence and have felt such fright as all pilots do, a number of memorable times hence, from the early years right up to the year of my retirement. Such things are visceral and not subject to "improvement", (thank goodness). But physiological and psychological human responses which sublimate rational responses may be mitigated, as I went to some trouble to define, by thorough training, an abiding mentality of cockpit discipline when the going gets interesting, and recent developments borne of the results of such cockpit chaos and rapid loss of SA as we see in the AF447 cockpit; these developments are known as CRM and SOPs.

To me, the cockpit is where the buck stops; it is those hands and minds that govern everyone's lives on board. But that does not excuse or turn focus away from organizational circumstances which "planted the garden" for this failure.

But truthfully, really, there is some hindsight bias at work in this. In terms of this organization and the larger industry, was UAS on anyone's radar as a top training priority? No, it was not, even bearing in mind that much had changed since the two initiating accidents which brought the loss of airspeed information into the industry's 'consciousness' from which it created the UAS cockpit responses. AF had addressed the issue as early as 2006, providing training as to when and how to apply the UAS drill. As with other professions with similar responsibilities and authorities, the standard is constant learning and engagement over and well above the formal recurrent training schedule and requirements. I don't think that's too tough a standard at all but, again similar to other professions, some do "just come to work"...

We all know that thirty-one other crews experienced this event and for all of them it was a log-book entry, just as it should have been. I'm sure each one would verify an initial fright - in fact one would wonder about a pilot who did not exhibit that initial reaction. To be sure, there was "startle", (if that's the way some want to put it), in every one of these events - I can tell you that there was such during a subtle failure of airspeed info (blocked pitot - airspeed acting as altimeter) on a B767 over the Rockies one dirty night!). But that's what training, SOPs and CRM are for - to replace fear quickly and provide the road map forward which sublimates initial fright to engender disciplined action. It works - thousands of minor incidents like this occur in airliners every day and they are non-events.

Gann would also have known and intuitively appreciated that 230T of mass does not lose energy in a few seconds to the point of falling out of the sky; - there is a "pilot's (sixth) sense" regarding the airplane involved here which seems to have been missing in the crew combination of AF447. A number of things come to mind: - the lack of clear command-and-control structure left by the captain and engendered by the airline, (ie, the F/O in the left seat should have taken control but out of deference to structure, did not), the possibility that sublimation of the airplane's situation, (ie, "not-serious-but-requiring-attention"), a desire to "do something" which led to the instantaneous, (2-second) reaction by the PF to remembered-drills for UAS done right after takeoff in the sim instead of doing 'nothing' for the moment, (as I had suggested in June, 2009).

Stall warning or no, there is nothing unclear about buffet, an unwinding altimeter that is going through FL's once every three seconds and the inability to arrest a 10,000fpm rate of descent.

I think OG has nailed the PIO matter. I've tried it in the sim, (not just the UAS sim session). The reducing oscillations are to me a successful response to the very sensitive roll that the airplane has in roll-direct; the PF got it under control. The sustained and increasing pitch is significant enough to be separately-intentional and not a result of inadvertent input while getting the roll under control.
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Old 19th Jun 2014, 17:12
  #132 (permalink)  
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Stall warning or no, there is nothing unclear about buffet, an unwinding altimeter that is going through FL's once every three seconds and the inability to arrest a 10,000fpm rate of descent.
- this is the crux of the matter. We can talk about 'startle'/'fright'/PIOs/FBW/UAS training/QRHs etc etc until the cows come home, but as PJ characteristically has pointed out, there was a big 'hole' in comprehension throughout the cockpit, and I recall beating my gums (sorry Sir... ) over and over again about 'symptoms of the stall' in days of yore, and a low (or in the AB case, NCD) IAS, high nose attitude and ginormous rate of descent SHOULD have switched on the light. Surely it is not unreasonable to expect that at least one of the three would have noticed?
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Old 19th Jun 2014, 17:36
  #133 (permalink)  
 
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Originally Posted by PJ2 View Post
But physiological and psychological human responses which sublimate rational responses may be mitigated, as I went to some trouble to define, by thorough training, an abiding mentality of cockpit discipline when the going gets interesting, and recent developments borne of the results of such cockpit chaos and rapid loss of SA as we see in the AF447 cockpit; these developments are known as CRM and SOPs.
And that is *exactly* what I meant by "improvement", so please accept my apologies if that wasn't clear.

But that's what training, SOPs and CRM are for - to replace fear quickly and provide the road map forward which sublimates initial fright to engender disciplined action. It works - thousands of minor incidents like this occur in airliners every day and they are non-events.
Absolutely - and all I was saying was that there may be some possible solutions to plug the gaps where the situation still goes pear-shaped in spite of those things.

The sustained and increasing pitch is significant enough to be separately-intentional and not a result of inadvertent input while getting the roll under control.
I certainly agree that the pitch input was separate from the roll inputs, and always have. What I do question is whether the intention was conscious or sub-conscious.

Last edited by DozyWannabe; 19th Jun 2014 at 18:21.
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Old 19th Jun 2014, 19:40
  #134 (permalink)  
 
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@DW
I certainly agree that the pitch input was separate from the roll inputs, and always have. What I do question is whether the intention was conscious or sub-conscious.
How do you reconcile the PF saying that he had been "stick back all the while" with a subconscious action. Surely his words explicitly state that PF intentionally stick backed as soon as he took control initiating the zoom climb.
IMHO one can question why he chose to stick back as a response to UAS however it is without doubt that it was intentional. I think an earlier poster suggested that his arm must have been aching with that continual pull pressure on the side stick. Maybe thats why he eased off momentarily a couple of times.
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Old 19th Jun 2014, 20:01
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Fair point, but there's an important distinction between "all the while", as you put it, and the actual English translation which is:

But Ive been at maxi nose-up for a while
(Final report Annexe 1 - p31)

"All the while" would imply that he's been pulling full stick back since the onset of AP disconnect, which does not tally with the DFDR trace. "For a while" implies that he has been consciously doing it for a period of time, but gives no clue as to when that period of time began.

Towards the end of the sequence, as the aircraft was descending in a mushy stall, it's fairly straightforward to reason why he may have decided to pull up. But at the beginning of the sequence, when the aircraft was still flying and the two F/Os had just discussed why they could not safely climb higher, it becomes a much more problematic issue to fathom out.
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Old 19th Jun 2014, 22:24
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Mental perception: clever sophisticated machines can fail in sophisticated ways . Crew convinced themselves that they were faced by something complicated and nothing should be taken at face value, including rushing noise, speed readings, altitude. Inverted stall warning treated accordingly.
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Old 19th Jun 2014, 22:57
  #137 (permalink)  
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From the SSFDR traces, regarding the PF's sidestick position from initiation of the climb to impact:

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Old 19th Jun 2014, 23:21
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Right, but to give it a bit more context:



The descent begins around 02:11:17, shortly followed by the PF's emphatic back-stick to the stop after 02:11:30 (which has the unfortunate consequence of completing the THS's drive to the full nose-up position, fouling the pitot tubes and consequently rendering the Stall Warning intermittent). Though it was completely the wrong thing to do, I can understand the instinct to pull the nose up when the altimeter begins to wind down.

What I have more trouble understanding is the motivation behind pulling the nose up past half-stick deflection around 02:10:09 (i.e. at AP disconnect), when the PF has just been explaining to the PNF why they are unable to safely climb to a higher flight level.

Last edited by DozyWannabe; 19th Jun 2014 at 23:41.
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Old 20th Jun 2014, 00:39
  #139 (permalink)  
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Dozy;

(which has the unfortunate consequence of completing the THS's drive to the full nose-up position, fouling the pitot tubes and consequently rendering the Stall Warning intermittent)
The elevator had sufficient authority to get the nose down - it was never stalled, (discussed at length in The Threads). Had the stick been held forward the aircraft would have recovered, while the THS was returning to it's cruise position, (that's the behaviour we saw in the sim).
Though it was completely the wrong thing to do, I can understand the instinct to pull the nose up when the altimeter begins to wind down.
Yes, it is instinctual and must be, to the extent possible, "trained out". Difficult though - better to avoid such a requirement altogether as such instinct has killed at least two other crews, (DC8 - test flight, B727 - placement flight) that we know of. It may have been a factor in the Trans-Canada-Airlines DC8 crash at St. Therese in the mid-60's.
What I have more trouble understanding is the motivation behind pulling the nose up past half-stick deflection around 02:10:09 (i.e. at AP disconnect), when the PF has just been explaining to the PNF why they are unable to safely climb to a higher flight level.
It isn't productive to wonder because, although we may imagine all kinds, I doubt if there is a specific reason. By this time the PF was lost/confused but unwilling to yield control to the more experienced man, who never pressed the take-over button for 15" or whatever it takes to lock the other sidestick out.

Last edited by PJ2; 20th Jun 2014 at 01:00. Reason: Add comment re 3rd quote
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Old 20th Jun 2014, 01:07
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Originally Posted by PJ2 View Post
The elevator had sufficient authority to get the nose down - it was never stalled ... Had the stick been held forward the aircraft would have recovered, while the THS was returning to it's cruise position, (that's the behaviour we saw in the sim).
Right, and it's what we saw in the sim as well (my summary on the megathread is linked here):
http://www.pprune.org/tech-log/46062...ml#post6793521

The caveat was that it took between 5 to 8 seconds of constant full nose-down on the sidestick for the THS to return to a "normal" position. Release to pitch-neutral too early and you run the risk of the THS causing the aircraft to pitch up again. Of course, if you're certain of what you're doing that's no problem - but if the environment is as disjointed as the AF447 flight deck seems to have been, I'd argue it'd take quite a bit of nerve to follow through.

Yes, it is instinctual and must be, to the extent possible, "trained out".
Right again - I guess the angle I'm coming from is asking whether there may be more consistently effective methods of training it out than those we have now. And while it may not be productive to merely wonder, as you say, the idea that 80% of a random sampling of pilots instinctively pulled up when startled by a Stall Warning - i.e. the effect was such that it completely negated their training - worries me greatly. It also can't help but make me think we're missing something.

Last edited by DozyWannabe; 20th Jun 2014 at 01:17.
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