@jcj:

I see incredibly smart people make silly mistakes at least twice a week. A bad day at the office is not something from which you can derive conclusions about intelligence and aptitude in general.

Not Deep Stall - Wrong Side of Drag Curve
 

Cland

Absolutely, this was not a 'classic' deep stall as Dozy points out with a high tail sat in the wake of the wing. However, it was a stable stall and almost certainly did not feel like a stall.

Many years ago I can remember playing in a simple single jet reducing to stall speed and then applying power and reducing further and sitting below normal stall speed on the power 'the wrong side of the drag curve'.

What the AF447 incident appears to be was a zoom climb into the stall and flying in that way you will get almost no buffet as you are using kinetic energy to stay up. Then at just the wrong point full TOGA power which holds the nose up keeping the extreme AOA but the power is insufficient to maintain height. So the aircraft now is the wrong side of the drag curve, its THS is nose up, its thrust is pushing nose up, and for a time the PF is pulling nose up. This is a totally repeatable stable stall with the aircraft held the wrong side of the drag curve 'sitting on its thrust' but with insufficient thrust to accelerate or maintain height. Had the PF not been so effective keeping the wings level, the aircraft might have fallen sideways out of it.

As people here have said recovery would be to put everything nose down, engines idle, trim THS nose down, push stick nose down - ideally to 40 degrees nose down or so then as the aircraft speed starts to increase slowly increase power and once the speed is above stall speed pull nose up to maintain 10 - 20 kts above stall speed increasing thrust to cruise thrust. But they didn't know they were holding the aircraft in a stable stall so they didn't even try.

Unfortunately, it would appear that training nowadays does not include anything that gets the pilot to feel how the aircraft behaves at extremes and how to get back. As many have said - the idea is not to get there. Fine - but that means you have to accept the occasional AFR447 when for whatever reason the aircraft and the crew find themselves outside their 'flight envelope' and discuss what could be wrong all the way to the surface. Now, as a fully paid up SLF that idea does not fill me with enthusiasm.

Again .. indeed .. I agree .. but ..
How are you making (and other) your conclusion about intelligence and aptitude in general ?
The pilots who wet their shirts in the Hudson may receive a gold medal (cause luck ?)
AF447 pilots will do not even receive a bronze medal posthumously (cause bad luck ?)
Why?
Because people will found that those of the Hudson were competent and those of the Atlantic were not
And this was derived from just 1 day in the office (a good day for one crew and a bad day for the other)
To put in view of all in the "offices" :
Amundsen:
Victory awaits him,who as everythings in order.
Luck we call it.
Defeats is definitely due for him,who has neglected to take the necessary precautions.
Bad luck we call it.

Hey JCJ!

In our profession the adage was:

"Luck" is when preparation meets opportunity.

Cheers...

Ian, that has always been my opinion. In my days of flying you didn't need training to do it the way you said. You learned it by gradually moving up the ladder to better aircraft in small steps. It didn't matter if your new airline job taught you or not, you could still do it. You were a real pilot and didn't need someone to nurse you through the course. That era is gone, unfortunately.

I have yet to fly or hover a Harrier and I do not know its stalling speed when relying solely on its wings to stay airborne. In the hover it must be relying on thrust to stay up - there is no "Proper Lift" from the wings.

AF447 was no Harrier and lacked sufficient thrust to remain aloft without very considerably more thrust than TOGA. ( Three or four times ?)

I would guess that the aeroelasticity of the wing would have increased the effective dihedral, tending to help the lateral stability when descending.

Think of this as a "thought exercise", not to be attempted without further thought !

I realize that this is the tech log, but could you Gents plz discuss the reasons the crew never recognized the UAS?

I doubt that Airbus will redesign the system, or that the regulatory agencies will demand such, therefore most of our discussion is academic. If we could agree on the reason the information and it's presentation was confusing{note}maybe we could make a difference.


{note} BEA hid behind "startled", I think totally confused is more likely.

Edited to add: they announced that they had lost speeds, but never seemed to recognize what they saw. Why not?

So why not install CCTV’s and put monitors in the cockpit so that pilots can actually see what is happening to their pitots, engines and control surfaces during flight?

So let us see a qualified pilot making periodic rounds of the passenger cabins during each flight, getting a feel for the mood of the passengers, looking out at the wings and engines and generally having a good look, smell and feel of the situation as a whole.

The Kegworth disaster could have been avoided if the problem engine had been correctly identified by CCTV, or even by a competent person simply looking out of the passenger cabin (smoke, flames etc.) before the wrong engine was shut down.

Seems to me that aircraft manufacturers and airline operators today are much too complacent regarding automated flight systems and pilot training programmes.

Aircraft should be designed to be flown (and to land) safely by fully competent and properly trained human pilots, any automated system should be designed to be used as an adjunct to the human pilot's skills, not vice-versa.

A few carefully chosen adjectives
 

1. Preposterous!

:suspect:

@Mr.Organ

Would you kindly explain why you consider my suggestions 'preposterous'?

It is noted that you have carefully edited my post to make it appear that all the quotes are mine, when in fact some of them are from The Problem of Automation: Inappropriate Feedback and Interaction, Not Over-Automation. Donald A. Norman UCSD, which is referred to in post No.1 of this thread.

@Carjockey
 

Carjockey,

I tried to distinguish between your comment and the quotes from the article by using quotation marks on the material from the article. Sorry, I should have made it more clear.

What bothered me were the references to keeping an eye on the passenger cabin, and cameras on the engines, which in no way address the oft-discussed issues about FBW/AP problems. Being "... physically isolated from the passengers and any difficulties that may be occurring within the passenger section of the plane. They are isolated from most of the physical structures of the aircraft" is a happenstance that's been with us since the 1930s, and not part of the equation at all.

Apologies if you found my criticism to be offensive. If corrected by one of the awesome line pilots here, I will grovel as required. :ouch:

@Mr.Organ

This a quote from Donald A. Norman UCSD, not from me.

These are your words, and I ask why you say that this is not part of the equation when it so clearly is.

Also I would ask you to consider that this is 2012, not 1930 something. Don't you think it's time that that people rid themselves of old and tired ideas and consider new and safer ones?

What exactly is wrong with having cameras on the engines and other critical parts?
They have been doing this in the marine industry for decades!

Carjockey, marine industry is not as critically limited by weight as is aviation industry, by orders of magnitude. (Former Naval Officer here, FWIW). I don't disagree at all regarding the value of monitoring tools in an engine room.

Also, for you both:

I recall as a boy, in the 60' and 70's, when on lengthy flights, how common it was for the passengers to see the Captain walking down the aisle, visiting with the passengers, making small talk, and making us feel welcome and well taken care of. (What I recall of the stewardesses from those days, as opposed to the CC of today, I won't digress into).

I miss that feature of air travel.

I suspect the 9-11 thing pretty much ended any of that being a norm, though I don't recall seeing as much of that in the 90's as I recall from my youth.

(discussion with Carjockey)
 

Sir, I'm well aware of that, and never said it was from you. I still find it to be preposterous.

I will agree to utterly disagree with you. Your saying so will not make it so. "Clearly"? Not clear at all. Seeing the passengers or watching parts of the aeroplane on a TV monitor during the AF447 accident would have had zero bearing on the outcome of this accident, nor any others that I can think of. AFAIC, Mr. Norman has revealed his lack of understanding of the problem by those contentions.

Please, don't confuse opinion with fact.

Banksters, Gangsters, Beancounters, SLF, Certification and Stability
 

Yes they are also many passionate and honnest people in aviation !
But when economy gets a condition for air safety, design, training, and for certification, we cannot put it in Rumour and News !

I am with John_Tullamarine : the definitions of stability are ICAO definitions ! specially when Test Pilots have to improve the aircraft so see very precisely if these definitions comply with the qualities of the aircraft.

In another post I already said that automation is a new science where 'Positive Law' has still to be said. And certifications of FBW show that engineers and pilots are not always the best to know the non-written law ! Some do the best they can risking their lifes, and other are... angels ?
That worries me really since I listened from the first certifier from the A320, as I asked her which documents she could use to certify it, that she asked for more papers... but had some pressures to sign without these documents, to certify an undescribed perhaps unknown domain of flight...

We could hope that AF447 report would clearly describe as a minimum the different "myriad" flight laws of this aircraft : but it seems that BEA could not do the best to clarify that lack ! One result is that we cannot have a consensus for a scientific and clear definition of "stability" :ugh:.

@Lonewolf

Thanks for your input but I have to disagree.

With the technology available today I believe that you could install as many cameras and monitors as were deemed necessary on a large passenger aircraft without weight becoming a critical factor.

The whole caboodle would likely be less than the weight of a single passenger.

I also remember the days when the Captain used to walk through the aircraft, and a very reassuring thing it was too.

I think we have all become far too paranoid since 9/11, and I would welcome a return to the days when flying was much more of a pleasure than a chore.

As a new pilot on the Car Ferry in 1960, I was told that someone had attempted to T/O with the nose doors not properly shut. (I think they got... not very fast !) Warning lights were fitted, before or after... I'm not sure.

The Herald of Free Enterprise was built in 1980 and sank in 1987.

Safety Engineers ought to look around, there might be a good idea, somewhere.

carjockey: there are a variety of ways to monitor the aircraft's performance and components that don't call for a camera.

The trap one may fall into is in sensory overload, and even mis interpretation of camera video input.

Then again, there was a cargo aircraft within the past two years that might have benefited from a camera in the cargo hold ...

This takes us back to how to define a requirement:
Nice to have?
Have to have?

Scratch the cameras on the engines, they are not needed. In fact, they would be of no use whatsoever, especially after dark. The important engine monitoring information is right in front of you and if something goes wrong you can both see it on the gages, or you will get a message and there are then procedures to follow when this happens. Having two cameras looking at 2 engines will not prevent shutdown of the wrong engine. Ascertaining left from right, port from starboard helps to keep from shutting down the good one.

Most probably - But the limit of efficacity for the elevators alone is reached earlier, and the stall cannot develop in such a pronounced way.

It HAS to be analyzed by the BEA - Where are they ?

To NOT trim an aircraft in a stall is a rule for all - Why obviously Airbus thinks differently ?

Where is the BEA ?

Where is the Analysis ?

Who is leading the investigation ?
The BEA ... or Airbus ?

HazelNuts39

Quote:
Maybe slightly but, IMHO, with full nose-up elevator maintained, not enough to unstall the airplane. I don't expect the airplane to have the straight-wing characteristic of a nose drop that can't be arrested.


The object of my earlier response was not recovery from Stall, but the alerting effect of an elevators only Nose Drop earlier in the sequence. My contention is that the THS' effect was counter to certification requirements, it disallowed an earlier and standard response of a Stalling airframe.

One cannot escape the fact that Autotrim, in this instance, would never be allowed in any aircraft, if it took away the standard dependence on both buffet, and Nose Drop


Besides, recovery from Stall requires the use of normal controls only, and nothing else. Having to depend on trim to recover, or avoid, is not allowed....

It can if you hold it there, and it was held there most of the way down.

Obviously there's a limit to how useful sim experience is outside of the envelope, but with consistent stick-forward it is possible to counteract the autotrim with plenty of time to spare - if it is noticed.


I suspect it was analyzed - and summarized in terms of the difficulty of pulling out of the stall if not trained to recognize it in the report. Accident reports tend to summarize rather than detail every experiment performed to the Nth degree - otherwise they'd routinely run into thousands of pages.

Case in point - the NTSB did not include the details of their experiments on the 737 rudder PCU in the original reports on UA535 and USAir427 because they could not prove a link. Only when a link was proven years later were those reports revised.

Well, they did put a hard autotrim limit on the A320 - it'd be a tragic irony if they didn't do it on the widebodies in response to pilot complaints regarding lack of full authority.

The BEA of course. Airbus are at more risk from a lack of transparency as opposed to secrecy.

BEA were hobbled after the memo they released that AIRBUS used to proclaim "There is nothing new to suggest any mechanical malfunction on the aircraft..."

That colored the reports, and prevented BEA from countering AIRBUS later.

Airbus have the full record, the complete CVR, DFDR etc. yet you are to suggest they do not control the outcome? Only BEA have also the records. The ones who do not disclose, create no more havoc than those who allow the suppression of information....satisfaction short of all the information is the sign of a partisan, a benefactor, even.

From CONFiture
"Most probably - But the limit of efficacity for the elevators alone is reached earlier, and the stall cannot develop in such a pronounced way."

My proposal is that the THS prevented a STALL, allowing entry into what can best be described as a MUSH.... Whatever you call it, it bore no resemblance to a normal STALL. Further confusing the pilots....

Normally (at least I hope) legal experts appointed by the judge hearing the case must also be in possession of all these evidences (includes access to parts of the plane recovered and postmortem analysis)
If this is not the case (which I do not think) it would be a very serious problem
(how do appraisal work if there is no evidence and documents to appraise? )

Jcjeant...

Howdy. You say:

"If this is not the case (which I do not think) it would be a very serious problem
(how do appraisal work if there is no evidence and documents to appraise? )"

Spot on. Who determines why a plaintiff shall have documentation, and prevent it from the public at large? It is absurd, the plaintiffs have been harmed, and the rest of us subject to the same harm! There is no compelling need to hide any of it, if it is allowed to be had by some. The plaintiffs will hear it, it is their entitlement, and having heard it, will have broken the dam for the rest of us.

Hearts cannot break twice.....it would be the wish of those lost, that those responsible NOT be allowed to hide like cowards.....

How? There's nothing to stop them saying different if contradictory evidence comes to light (again, see UA535 - it took years, during which time a final report was released by the NTSB that considered the evidence inconclusive).

Let's look at that point from another angle - how would hiding problems benefit Airbus?

Er, nose-high attitude leading to loss of control in pitch and bank with a rapidly unwinding altimeter? Sounds a lot like a stall to me...

Er, nose-high attitude leading to loss of control in pitch and bank with a rapidly unwinding altimeter? Sounds a lot like a stall to me...

The pitch was not lost, and bank was controlled.... And it remained nose high....

"but it was the pilot who held it nose high".......no one knows, it was the pilot who held the stick back, and the THS that held the nose.

The thing that concerns is the lack of the only two airframe warnings available, buffet and Nose drop. Besides, what matters is what PF thought, not you nor I...

The nose came down while he was pulling up - if that's not loss of control, then what is? And the bank was not controllable via aileron once the stall had begun

It is possible to counteract THS with elevator (albeit with significantly reduced authority), however the THS was in the position it was because the pilot had held the stick back for so long.

According to the CVR, both were in evidence - but then it seems to me that you will always find something else to be "concerned" about whenever your current concern is disproved.

Wouldn't you say it's an indication of running out of plausible arguments when one demands proof of something that it impossible to prove?

Again I agree .. but ...
hiding problems .. does not mean not to address them ...
Everything is a matter of doing it gently .. without alarming that matter ..
Seen from this angle .. this can be beneficial for Airbus ...
There is an appropriate expression in French
On lave son linge sale en famille
Wash your dirty linen in the family circle

@jcj:

Not at all - McDonnell Douglas tried that in the '70s and the black mark it left on their reputation and that of the DC-10 was never truly erased.

To my mind there was never been an "under the radar" update in terms of either hardware or software to a FBW Airbus type.

If Airbus make some modifications on their aircraft after the AF447 accident (related to) ... this will be the explicit recognition that their plane(s) had problem (s) (was not sure) before the accident ...
So in effect .. this will not be beneficial for Airbus and may have unfortunate consequences for Airbus at the trial (even if their answer is "we don't know before")
And it's in contradiction with their former declaration in the press ...

According to the CVR, both were in evidence - but then it seems to me that you will always find something else to be "concerned" about whenever your current concern is disproved.

Show us where. Both stall cues please. From the CVR. Not the DFDR. In evidence, and acknowledged by the pilots....

Not really - the report acknowledges pre-existing faults with the pitot tubes, which is the reason Airbus was charged alongside AF.

Not true - the declaration was notably specific, and stated that there was no *mechanical failure* over and above the pitot tube problem that was already known. There was no mention in that declaration of possible contentious design issues or unforeseen human interface problems. The statement did not state that the aircraft was perfect - merely that it behaved as designed. Whether that design still stands up in the face of the other evidence is open to question.

The presence of the cues versus acknowledgement by the pilots are two separate issues, as I'm sure you well know. The CVR proves that they missed several obvious cues - both electronic and aerodynamic.

This is not to say that they were bad pilots, simply that they were in the wrong place at the wrong time.

So you agree now, that the NU trim should have been designed to stop like it does in the A 320. That is a big advance in this discussion.

You have evidence for your assumption concerning the cause of this change in design? Afaik there might be lot of other reasons, why do you suggest it was caused by pilot input?

- I have missed that fact - can you elaborate a little please? Does it have the necessary option to deliberately over-ride as I proposed months ago following PGF?

- unless you have evidence that control in pitch was 'lost' I think that line is misleading. I think you are confusing a known aerodynamic shift in CP with 'loss of control'? I understood from the report that they were in fact able to maintain a high nose attitude in pitch with side-stick/THS and/or lower the nose occasionally with side stick? Is that not 'control', even if 'up' was the wrong 'control'? Am I wrong?

@Lonewolf

It's nice to have and I suggest that yes, you have to have.

If your instruments go haywire then at least you have another very valuable point of reference.

As stated previously, pilots are reliant on their flight instruments. If your instrument readings are questionable than a visual back-up on engines and control surfaces (via CCTV) surely cannot be a bad thing.

The Kegworth accident is an excellent example. If the pilots had been able to visually verify which was the problem engine, the accident could have been avoided.

the stall
 

I find it somewhat interesting that for a short time there were only three pilots in the world who have ever actually performed this particular maneuver...

We have the DFDR traces of short term snippets of SS movement and resulting aircraft response without any long term validation nor an AOA ever below 30 degrees...

PPRuNe has 2 or 3 pilots who have objectively and insightfully described their experiences with this maneuver as actually performed in an A330 simulator...

yet we have a plethora of posters who have never touched an A330 SS who 'know' exactly how it must have been. :confused:

I have looked at my logbooks, and I can say that I have experienced roughly three hundred Stalls, always on purpose, and never alone.

Maybe half that number of Spins, again, always on purpose, and never solo.

I have no idea, what the 330 is like. If I have suggested I have even a clue, I am deeply sorry. I will say that I have experienced controlled descents with a Stalled wing (s), but that is not pertinent either. I know.

Bottom line. Virtually none of the conclusions expressed here give me comfort. I think the pilots are given short shrift, and through time, innuendo, slur, and lazy data have cemented their legacy. And that is so wrong.

On the A320 the autotrim stops (at about 6 degrees nose up if I recall correctly), and if you need more trim than that it must be wound on manually with the wheel - so the wheel in effect becomes the override mechanism.

Perhaps I should have been clearer - while a degree of control was possible throughout the sequence, the fact that the nose dropped (due to stall) when the command given was nose-up - i.e. for that short period not responding to the controls - meant that the aircraft behaviour was consistent with stall.

I neither agree nor disagree - I don't have the evidence to support a case for one design being better or worse than the other.

I didn't suggest that was the cause (as you point out, I don't have the data) - I said it would be ironic (in the tragic sense) if the design change was a response to criticism based on perceived lack of authority.

Think of it as a bit of whimsical conjecture, not a serious claim.

Auto trim
 

DW say:
3 degrees

:8