AF 447 Thread No. 9
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@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.
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.
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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.
How do I know AF447 wasn't deep-stalled? Well, I started by paying attention in high school science classes, which helped me to understand aerodynamics lessons during my flight training. One of them involved deep stall and I learnt it has specific meaning: it is stall which cannot be recovered by conventional means such as actions on elevator, stabilizer or power. While AF447 never fully recovered, mere reduction of power or just moving the elevators towards the neutral (while never reaching it) abruptly decreased its AoA - which is incompatible with deep stall as we know it. Now if your goal is to be taken seriously in discussion, you won't go a long way if you take well established terms and start assigning them just your own definitions.
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.
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@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.
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.
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.
Last edited by jcjeant; 27th Jul 2012 at 02:18.
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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.
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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 !
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 !
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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?
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?
Last edited by TTex600; 27th Jul 2012 at 12:05.
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For one, the sheer size of the plane means that the crew cannot know all that is happening. They are 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. Even more important than physical isolation is the mental isolation caused by the nature of the controls. The automation tends to isolate the crew from the operations of the aircraft because the automatic equipment monitors and controls the aircraft, providing little or no trace of its operations to the crew, isolating them from the moment-to-moment activities of the aircraft and of the controls. On the one hand, this combination of relative physical and mental isolation from the details of flying helps contribute to the safety by reducing workload and reliance on possible human variability or failure. On the other hand when the automatic equipment fails, the crew's relative isolation can dramatically increase the difficulties and the magnitude of the problem faced in diagnosing the situation and determining the appropriate course of action.
Physical isolation would be alright if the crew were still up to date on the critical states of the device being controlled. The problem is that, increasingly, the physical isolation is accompanied by a form of mental isolation. Zuboff (1989) describes the control room of a modern paper mill: where once the operators roamed the floor, smelling, hearing and feeling the processes, now they are poised above the floor, isolated in a sound-isolated, air-conditioned, glass control room.
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.
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A few carefully chosen adjectives
"For one, the sheer size of the plane means that the crew cannot know all that is happening. They are 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."
"The automation tends to isolate the crew from the operations of the aircraft because the automatic equipment monitors and controls the aircraft, providing little or no trace of its operations to the crew"
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.
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@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.
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.
Last edited by Carjockey; 27th Jul 2012 at 15:16. Reason: Update
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@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.
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.
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@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!
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.
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.
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.
Last edited by Lonewolf_50; 27th Jul 2012 at 16:05.
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(discussion with Carjockey)
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.
Please, don't confuse opinion with fact.
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Banksters, Gangsters, Beancounters, SLF, Certification and Stability
Originally Posted by John_Tullamarine
Franzl,
The general dumbing down of things piloting is an extreme worry to most of us. If the systems design folks could guarantee that they get it all correct (which, of course, they can't .. and don't) it might be a different matter .. but, until they can, the folks up front are the last ditch defence and if they don't know much beyond "light A ON .. button B PRESS" we are better off going fishing.
The beancounting fraternity has a lot to answer for I suggest.
[Thanks for the PM offer]
The general dumbing down of things piloting is an extreme worry to most of us. If the systems design folks could guarantee that they get it all correct (which, of course, they can't .. and don't) it might be a different matter .. but, until they can, the folks up front are the last ditch defence and if they don't know much beyond "light A ON .. button B PRESS" we are better off going fishing.
The beancounting fraternity has a lot to answer for I suggest.
[Thanks for the PM offer]
Originally Posted by PJ2#651
Originally Posted by roulishollandais
It is fashionable to analyze aviation and all events in the light of the economy. It needs to be tried, but this seems to me erroneous
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"
.
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@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.
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.
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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.
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?
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?
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Original post by Carjockey: What exactly is wrong with having cameras on the engines and other critical parts?
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Originally Posted by HN39
Without autotrim, the PF would have pulled more to follow the FD, or to maintain 15°, or 12.5° pitch, or to arrest the V/S.
...
But the culprit is not autotrim, without it the airplane would still have stalled.
...
But the culprit is not autotrim, without it the airplane would still have stalled.
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.
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 ?
Last edited by CONF iture; 28th Jul 2012 at 00:41.