AF447 wreckage found
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Validity of intruments
voyachan, safetypee, etc.
I understand pilots are trained on where the instruments get their data, but how often do pilots practice that? Isn't it possible that, given the circumstances, they weren't able to work out quickly enough which instruments they could believe or shouldn't believe? (Especially if they aren't sure what has failed.)
I understand pilots are trained on where the instruments get their data, but how often do pilots practice that? Isn't it possible that, given the circumstances, they weren't able to work out quickly enough which instruments they could believe or shouldn't believe? (Especially if they aren't sure what has failed.)
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Software design
Lonewolf50, as someone with an IT background, including supervision of programmers, I have to suspect a fault in the software, in its not matching real human behaviour.
I've found programmers design software in a particular way, and if human people behave differently the programmers are resistant to changing the software. A simple example is entering a date. People might enter a date various ways, but programmers often don't like to design the program to accept any valid date. Often programmers will insist people should have to learn how to enter the date a particular way.
I suspect that is part of why the handling of stall warnings is handled badly. If the warning is supposed to be continuous then it should be continuous if the aircraft is detected to be stalled while in the air. Don't assume pilots will figure out that the plane is still stalled and but that the stall warning stopped for some other reason. Don't assume a pilot who did the right thing will figure out that a new stall warning is misleading.
In this thread it has often been said that somehow the pilots seemed to not realize that they were stalled, or perhaps thought they had gone overspeed. With all respect to those who think the pilots had to be to blame, it is not likely that three experienced pilots all made such errors unless the instrumentation and the way it presented information to them misled them.
BTW, I was surprised when people reacted with surprise to the suggestion that the FBW system should have said why it gave control back to the pilots. I understand the reaction was due to a conceptual understanding of the whole point of the FD system. But I suggest perhaps that should be given a second look. It seems like some information about that was given to the pilots, but perhaps it might in some situations be useful if that information was more clearly available.
I won't go into the weather issue. That, after all, is at least in part a judgement call. And many here have noted that pilots have flown through worse conditions many times without crashing. It could only have been at most a contributing factor, not something sufficient to cause the crash.
I've found programmers design software in a particular way, and if human people behave differently the programmers are resistant to changing the software. A simple example is entering a date. People might enter a date various ways, but programmers often don't like to design the program to accept any valid date. Often programmers will insist people should have to learn how to enter the date a particular way.
I suspect that is part of why the handling of stall warnings is handled badly. If the warning is supposed to be continuous then it should be continuous if the aircraft is detected to be stalled while in the air. Don't assume pilots will figure out that the plane is still stalled and but that the stall warning stopped for some other reason. Don't assume a pilot who did the right thing will figure out that a new stall warning is misleading.
In this thread it has often been said that somehow the pilots seemed to not realize that they were stalled, or perhaps thought they had gone overspeed. With all respect to those who think the pilots had to be to blame, it is not likely that three experienced pilots all made such errors unless the instrumentation and the way it presented information to them misled them.
BTW, I was surprised when people reacted with surprise to the suggestion that the FBW system should have said why it gave control back to the pilots. I understand the reaction was due to a conceptual understanding of the whole point of the FD system. But I suggest perhaps that should be given a second look. It seems like some information about that was given to the pilots, but perhaps it might in some situations be useful if that information was more clearly available.
I won't go into the weather issue. That, after all, is at least in part a judgement call. And many here have noted that pilots have flown through worse conditions many times without crashing. It could only have been at most a contributing factor, not something sufficient to cause the crash.
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Hi,
Again (broken record ?) you also confuse conspiracy and cover up ... two things completely different
A cover-up is an attempt, whether successful or not, to conceal evidence of wrong-doing, error, incompetence or other embarrasing information
A conspiracy is nothing but a secret agreement of a number of men for the pursuance of policies which they dare not admit in public
Because you are too stupid to realise that there is no conspiracy
A cover-up is an attempt, whether successful or not, to conceal evidence of wrong-doing, error, incompetence or other embarrasing information
A conspiracy is nothing but a secret agreement of a number of men for the pursuance of policies which they dare not admit in public
Last edited by jcjeant; 23rd Jun 2011 at 11:44.
jcjeant, not quite.
Not really. If you are trying to conceal information that multiple people have access to, then you need to get a group of people to agree to a plan to do something unethical. <= That's a conspiracy, is it not? 
Absent a plan to conceal, then the information will be available.
Suggest you forward your concerns of a cover up to:
1. Members of French Parliament
2. BEA
3. Law enforcement authorities in France (who would have an interest in illegal activity)
This set of forums, however, appears not to be the place you'll get satisfaction.
Why? For one, you are asking people to prove a negative. That's a dead end. ("There must be a cover up if there isn't evidence that there isn't one." Sorry, that isn't necessarily so. You are assuming a conclusion without a valid premise AND evidence.)
Two, you assume an answer in your question, when that answer hasn't been supported by evidence. That's a case of asking "have you stopped beating your wife."
Please give it a rest.
Again (broken record ?) you also confuse conspiracy and cover up ... two things completely different
Absent a plan to conceal, then the information will be available. Suggest you forward your concerns of a cover up to:
1. Members of French Parliament
2. BEA
3. Law enforcement authorities in France (who would have an interest in illegal activity)
This set of forums, however, appears not to be the place you'll get satisfaction.
Why? For one, you are asking people to prove a negative. That's a dead end. ("There must be a cover up if there isn't evidence that there isn't one." Sorry, that isn't necessarily so. You are assuming a conclusion without a valid premise AND evidence.)
Two, you assume an answer in your question, when that answer hasn't been supported by evidence. That's a case of asking "have you stopped beating your wife."
Please give it a rest.
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Denise Moore;
Perception and logic are not necessarily good bedfellows.
A system designed to provide prior warning of a stall can and will fail when its warning is dealt with incorrectly. A bit like the original photovoltaic door guard; it told you when the beam was broken but didn't discriminate between someone entering or leaving.
With all respect to those who think the pilots had to be to blame, it is not likely that three experienced pilots all made such errors unless the instrumentation and the way it presented information to them misled them.
A system designed to provide prior warning of a stall can and will fail when its warning is dealt with incorrectly. A bit like the original photovoltaic door guard; it told you when the beam was broken but didn't discriminate between someone entering or leaving.
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FBW could not change the laws of physics, if you use cambered airfoils, the lift of the wing has to be upward and that of the tail downward at 0° AOA to have some kind of positive stability, when the confusers go on leave.
1) Mean camber would be -ve (e.g. on bottom surface, as installed)
2) Camber of a supercrital aerofoil section is not always that obvious, max thickness often far back (>50%) and strange camberlines used, but nevertheless, (1) applies.
3) Camber doesn't determine whether foil is lifting one way or other, it determines the ZLA (zero lift angle), Cl max, Cm and Cd curves.
4) Camber optimises the drag of the aerofoil for a given AoA... that is, in this case, the typical cruising Lift Coefficient would be determined and the shape (and hence camber-line) finalised, such that the low-drag-bucket was at that CL (-ve in this instance, however marginally - stability requires it)
5) The aerofoil is working in considerable (and varying) downwash from the mainplane, a stabilising situation.
6) Little of this has much to do with FBW or the somewhat aft CG during cruise; as has been said, this CG is set to offset cruise trim drag, not to create a zero or -ve stability FBW aircraft for maneouvrability reasons.
So the camber determines little, other than the setting angle of the THS and the actual Cd (drag) . As we know from watching amazing outside square loops during aerobatics, even quite + cambered foils such as on a Spitfire, can be flown upside down - they are just draggier and have lower maximum Cl (Clmax)
Denise
A significant consideration conflicting with that is the problem of spurious warnings. That is a non trivial human/machine interface problem that has to be addressed before a particular machine hits the field. For many systems, the weight on wheels switch feature that influences other systems is a way to deal with spurious warnings on the ground. But those can go bad also. I think we have a thread on an accident in Spain where that feature was part of the problem.
While I agree as a general principle, a driving design paradigm is stall avoidance. That is also a flight imperative __stall avoidance__ particularly in passenger carrying air transport. That mind set, or philosophy, will have knock on effects when the final design and integration decisions are made.
Those estimates are hopefully made as a best guess, since there is so much unknown about this accident.
OR, and this is a big OR
Their understanding of what was displayed was influenced by training, environment, or being faced with a novel situation.
I suspect that is part of why the handling of stall warnings is handled badly. If the warning is supposed to be continuous then it should be continuous if the aircraft is detected to be stalled while in the air.
Don't assume pilots will figure out that the plane is still stalled and but that the stall warning stopped for some other reason. Don't assume a pilot who did the right thing will figure out that a new stall warning is misleading.
In this thread it has often been said that somehow the pilots seemed to not realize that they were stalled, or perhaps thought they had gone overspeed.
With all respect to those who think the pilots had to be to blame, it is not likely that three experienced pilots all made such errors unless the instrumentation and the way it presented information to them misled them.
Their understanding of what was displayed was influenced by training, environment, or being faced with a novel situation.
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Software Design
Hi Denise Moore,
There has been an interesting and continuing discussion regarding the software/human interface in Tech Log, AF447 Thread #4 which is the current one. If you have not done so, you may want to read several posts:
#273, Pg.14
#280, Pg.14
#309, Pg.16
and,
#319, Pg.16
They are all posts by Gums. He flew some of the very first FBW F-16 Falcon fighters that were originally known as Vipers. I think he has some of the concerns you have.
As an engineer, we tend to think in terms of probabilities of failure, e.g., 10⁻⁹ or thereabouts, and designs are formulated and tested on a probability basis. What often is not thought of is "possibility" of failure. Possibilities are real. This was pointed out by PJ2 in a post and he gave a link to an interesting article:
http://leeclarke.com/docs/clarke%20t...gnificance.pdf
There has been an interesting and continuing discussion regarding the software/human interface in Tech Log, AF447 Thread #4 which is the current one. If you have not done so, you may want to read several posts:
#273, Pg.14
#280, Pg.14
#309, Pg.16
and,
#319, Pg.16
They are all posts by Gums. He flew some of the very first FBW F-16 Falcon fighters that were originally known as Vipers. I think he has some of the concerns you have.
As an engineer, we tend to think in terms of probabilities of failure, e.g., 10⁻⁹ or thereabouts, and designs are formulated and tested on a probability basis. What often is not thought of is "possibility" of failure. Possibilities are real. This was pointed out by PJ2 in a post and he gave a link to an interesting article:
http://leeclarke.com/docs/clarke%20t...gnificance.pdf
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Denise Moore wrote:
From my limited 9000 hours along 36 years flying and gained understanding, a fliable aircraft, even when lacking an instrument or two, when CFIT from 38,000 feet, is the result of pilot performance. Not to mention how he got there. Or the full aft sidestick input held throughout the fall. Additionally, one doesn't have to be an experienced captain, just a rated aviator, to know how to avoid a CB, and how to trim to neutral during stall recovery. Altough engine thrust when initially applied here is counterproductive, it shouldn't affect recovery by much as a full forward SS plus neutral trim would have effected a successful recovery by FL200.
With all respect to those who think the pilots had to be to blame, it is not likely that three experienced pilots all made such errors unless the instrumentation and the way it presented information to them misled them.
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Novel situation
Lonewolf_50, I would go with the novel situation idea.
After all, given how much has been done to eliminate accidents, most common situations that would lead to accidents are going to be covered off by pilot training and experience, aircraft design, etc. I suppose a pilot could make a "rookie mistake" and in some situations that could cause a crash. But these days most crashes are likely to involve a confluence of different factors that if they had not combined wouldn't each have by themselves resulted in a crash. It is likely to be a novel situation.
I suppose one implication might be to add something to basic pilot training. Try to also have training to help pilots to recognize and deal with novel situations. (Aside, pilots who flew in wars might, besides having just more experience, also have had to develop more ability to deal with novel situations.)
Even though a situation might be novel, the pilot's ability to deal with it is still going to be affected by the way the aircrafts instrumentation and systems work. How much useful information did the pilots of AF447 get? What were they able to do to command the aircraft? We really still have to go to those factors as the underlying "fault". Unless pilot qualifications start taking into account the person's ability to deal with novel situations, blaming it on a novel situation isn't all that helpful. Even though, yes, it was a novel situation.
Like others, I'm puzzled about what happened during the final 3 minutes or so, and why there is so far no information about that. I find it unlikely that all three pilots were stunned and baffled and just did nothing. Unless maybe the physics of the situation made it impossible for them to do anything? Otherwise it is likely that one of them at least tried to do something to save the plane and their lives.
After all, given how much has been done to eliminate accidents, most common situations that would lead to accidents are going to be covered off by pilot training and experience, aircraft design, etc. I suppose a pilot could make a "rookie mistake" and in some situations that could cause a crash. But these days most crashes are likely to involve a confluence of different factors that if they had not combined wouldn't each have by themselves resulted in a crash. It is likely to be a novel situation.
I suppose one implication might be to add something to basic pilot training. Try to also have training to help pilots to recognize and deal with novel situations. (Aside, pilots who flew in wars might, besides having just more experience, also have had to develop more ability to deal with novel situations.)
Even though a situation might be novel, the pilot's ability to deal with it is still going to be affected by the way the aircrafts instrumentation and systems work. How much useful information did the pilots of AF447 get? What were they able to do to command the aircraft? We really still have to go to those factors as the underlying "fault". Unless pilot qualifications start taking into account the person's ability to deal with novel situations, blaming it on a novel situation isn't all that helpful. Even though, yes, it was a novel situation.
Like others, I'm puzzled about what happened during the final 3 minutes or so, and why there is so far no information about that. I find it unlikely that all three pilots were stunned and baffled and just did nothing. Unless maybe the physics of the situation made it impossible for them to do anything? Otherwise it is likely that one of them at least tried to do something to save the plane and their lives.
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Probabilities and possibilities
Turbine D, thanks for the interesting links.
I would add that, adding to the difficulty is also that known possibilities can be ignored.
Consider Katrina. The risk of such a hurricane wasn't exactly unknown, but for various other reasons steps weren't taken to cope with that. The recent flooding in Australia is another example. Despite what was repeated constantly, the flooding wasn't unprecedented. Flooding had happened often in those areas, and the governments there actually have decades of records of the flooding. For various reasons, they just hadn't done anything to deal with flooding.
This obviously relates to replacement of the pitots. It probably should have been harder to delay their replacement, by making it harder for the various parties involved to decide that isn't such an important issue.
I would add that, adding to the difficulty is also that known possibilities can be ignored.
Consider Katrina. The risk of such a hurricane wasn't exactly unknown, but for various other reasons steps weren't taken to cope with that. The recent flooding in Australia is another example. Despite what was repeated constantly, the flooding wasn't unprecedented. Flooding had happened often in those areas, and the governments there actually have decades of records of the flooding. For various reasons, they just hadn't done anything to deal with flooding.
This obviously relates to replacement of the pitots. It probably should have been harder to delay their replacement, by making it harder for the various parties involved to decide that isn't such an important issue.
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Fault
Opherphen, obviously you're right that pilot performance is involved. And the pilots of AF447 might have made mistakes. But I'm not sure, whether it will be useful to blame the pilots even if they did make mistakes. As I'm sure you realize, a serious look has to be taken at WHY they made any mistakes that they made. We might never know why they didn't divert from the weather, but maybe we can guess. And if indeed they didn't realize they were stalled, WHY didn't they realize they were stalled?
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Whilst I understand that there are many factors....
There are certain situations where the stall warning and overspeed will sound at the same time, based on an actual previous pitot/static errors that resulted in a crash.
The key lesson to recover is POWER + ATTITUDE = PERFORMANCE, the message is if in doubt set a logical POWER + ATTITUDE and the PERFORMANCE will work.
Like Colgan Air, if you lose sight of the basic tenants of flying and chase an altitude, attitude or performance without consideration of all factors you will not stand a chance. If in doubt, set an AoA using a logical ATTITUDE (which will closely relate to AoA), set a reasonable POWER, the laws of physics will not cause a catastropic break up unless the AHRS has failed and you are accidentally set 20 degs nose low.
If you performance fly and chase an airspeed, altitude or VSI reading you will lose sight of the basics.
No criticism of others, I know that at night in a CB it is confusing, but its just how I fly.
There are certain situations where the stall warning and overspeed will sound at the same time, based on an actual previous pitot/static errors that resulted in a crash.
The key lesson to recover is POWER + ATTITUDE = PERFORMANCE, the message is if in doubt set a logical POWER + ATTITUDE and the PERFORMANCE will work.
Like Colgan Air, if you lose sight of the basic tenants of flying and chase an altitude, attitude or performance without consideration of all factors you will not stand a chance. If in doubt, set an AoA using a logical ATTITUDE (which will closely relate to AoA), set a reasonable POWER, the laws of physics will not cause a catastropic break up unless the AHRS has failed and you are accidentally set 20 degs nose low.
If you performance fly and chase an airspeed, altitude or VSI reading you will lose sight of the basics.
No criticism of others, I know that at night in a CB it is confusing, but its just how I fly.
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Come on now everyone - just like the other thread I keep seeing "they were in a cb" "they didn't divert for weather" - where exactly have I missed these facts? It is looking as if imagination is becoming fact again.
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Opherben-:
As someone who only ever flew gliders and light singles, it's probably presumptuous of me to comment, Opherben. But, to my mind, that raises the immediate question of how any of us know that the aeroplane was 'flyable' at all - particularly given the 'full up' position of the 'trimmable horizontal stabiliser' (better known, in my flying days, as the 'tailplane'?
To quote the BEA report on an earlier (2008) all-killed accident in an A320 off Perpignan:-
Further on in the 2008 Perpignan report, the BEA states:-
The aeroplane attitude increased sharply and its speed dropped to the point
that rendered it practically uncontrollable, the flight control surfaces becoming
ineffective due to the low speed and the high angle of attack. The aeroplane
stalled again, this time irrecoverably, bearing in mind the aeroplane’s altitudeand without any crew inputs on the trim wheel and the thrust levers. The loss of control was thus caused by a thrust increase performed with afull pitch-up horizontal stabilizer position. This position and the engine
thrust made pitch down control impossible.
http://www.bea.aero/docspa/2008/d-la...a081127.en.pdf
In the case of AF447, the BEA's phrasing seems to be almost eerily similar:-
Just seems to me that it's far too early to put this one down to 'pilot error.' especially since the BEA's report leaves out so many things that the BEA must already know?
Or does anyone think that the two pilots on the flight deck only noted the 'change in law' and then said nothing else until the 'no indications' exchange after they'd lost 20,000 feet?
Or that the Captain, who got back to the flight deck in a commendably short time, said nothing at all?
"....a fliable aircraft, even when lacking an instrument or two, when CFIT from 38,000 feet, is the result of pilot performance. Not to mention how he got there. Or the full aft sidestick input held throughout the fall. Additionally, one doesn't have to be an experienced captain, just a rated aviator, to know how to avoid a CB, and how to trim to neutral during stall recovery. Altough engine thrust when initially applied here is counterproductive, it shouldn't affect recovery by much as a full forward SS plus neutral trim would have effected a successful recovery by FL200."
To quote the BEA report on an earlier (2008) all-killed accident in an A320 off Perpignan:-
When the stall warning sounded, the Captain reacted by placing the thrust levers
in the TO/GA detent and by pitching the aeroplane down, in accordance with
procedures.
procedures.
The nose-down input was not however sufficient for the automatic compensation
system to vary the position of the horizontal stabilizer, which had been progressively
deflected to the pitch-up stop by this system during the deceleration.
system to vary the position of the horizontal stabilizer, which had been progressively
Between 15 h 44 min 30 and 15 h 45 min 05, the stabiliser moved from -4.4° to -11.2°
corresponding to the electric pitch-up stop. It stayed in this position until the end
of the recording.corresponding to the electric pitch-up stop. It stayed in this position until the end
The aeroplane attitude increased sharply and its speed dropped to the point
that rendered it practically uncontrollable, the flight control surfaces becoming
ineffective due to the low speed and the high angle of attack. The aeroplane
stalled again, this time irrecoverably, bearing in mind the aeroplane’s altitudeand without any crew inputs on the trim wheel and the thrust levers. The loss of control was thus caused by a thrust increase performed with afull pitch-up horizontal stabilizer position. This position and the engine
thrust made pitch down control impossible.
In the case of AF447, the BEA's phrasing seems to be almost eerily similar:-
At 2 h 10 min 51 , the stall warning was triggered again. The thrust levers were positioned in the TO/GA detent and the PF maintained nose-up inputs. The recorded angle of attack, of around 6 degrees at the triggering of the stall warning, continued to increase. The trimmable horizontal stabilizer (THS) passed from 3 to 13 degrees nose-up in about 1 minute and remained in the latter position until the end of the flight.
One more thing to add - a final quote from the BEA 'note' on AF447; that, at a bit over 10,000 feet, the PF (possibly acting on the orders of the captain, who, according to that Der Spiegel leak, correctly diagnosed that the problem was a stall):-
At 2 h 12 min 02, the PF said "I don’t have any more indications", and the PNF said "we have no valid indications". At that moment, the thrust levers were in the IDLE detent and the engines’ N1’s were at 55%. Around fifteen seconds later, the PF made pitch-down inputs. In the following moments, the angle of attack decreased, the speeds became valid again and the stall warning sounded again.
Or does anyone think that the two pilots on the flight deck only noted the 'change in law' and then said nothing else until the 'no indications' exchange after they'd lost 20,000 feet?
Or that the Captain, who got back to the flight deck in a commendably short time, said nothing at all?
Last edited by RWA; 24th Jun 2011 at 14:47.
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Yes....
In short then we have lost two similar aircraft in short order due to loss of control of basic pitch attitude, despite the power to recover being at the pilots fingertips and staring him/her in the eyes... that Trim Wheel, the elephant in the cockpit.
Which raises many questions, one of which must be:-
Why are the many training bodies not addressing recovery from stalls (of all styles and reasons), rather than simply illustrating their avoidance and prevention.
Another would be:
Why is the THS given this much automatic command and power in inappropriate situations... a THS reaching above a given NU setting, close to maximum, say 10 degrees; should have had a very specific cockpit warning as it runs through that threshold:
<<Eee Aw Eee Aw>> "THS 10 degrees NU and increasing"
If not before, certainly after Perpignan ... and NU trimmed near-stall incidents are probably more numerous than we know about.
Gatwick and Schiphol are two mentioned somewhere on these forums.
Low slung podded engines combined with a heavily NU THS can get you there... and that's not a good place to be, even at 35,000 ft.in this case.
In short then we have lost two similar aircraft in short order due to loss of control of basic pitch attitude, despite the power to recover being at the pilots fingertips and staring him/her in the eyes... that Trim Wheel, the elephant in the cockpit.
Which raises many questions, one of which must be:-
Why are the many training bodies not addressing recovery from stalls (of all styles and reasons), rather than simply illustrating their avoidance and prevention.
Another would be:
Why is the THS given this much automatic command and power in inappropriate situations... a THS reaching above a given NU setting, close to maximum, say 10 degrees; should have had a very specific cockpit warning as it runs through that threshold:
<<Eee Aw Eee Aw>> "THS 10 degrees NU and increasing"
If not before, certainly after Perpignan ... and NU trimmed near-stall incidents are probably more numerous than we know about.
Gatwick and Schiphol are two mentioned somewhere on these forums.
Low slung podded engines combined with a heavily NU THS can get you there... and that's not a good place to be, even at 35,000 ft.in this case.
Last edited by HarryMann; 24th Jun 2011 at 22:50.
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Technologs ask questions.
Decision makers, having studied the evidence before them must provide timely answers. Two years on, the community, the customers, the families all need answers. I have conducted complex air accident investigations as chairman, in which I grounded the relevant fleet pending certain fixes, whose implementation was completed in the same week the accident took place. A question of attitude, which leads to proper operations risk management (ORM). I haven't seen ORM mentioned here, odd.
I maintain that a fliable aircraft CFIT is the result of pilot performance. Evident in the last BEA report.
Perpignan isn't the only similar case, they are numerous and indicate a fundamental conceptual error in pilot-aircraft interface. No matter how many pilots like to fly Airbus aircraft, they too fail to see the major shortcomings in that design.
Anything else is technologist wording, not managerial straight to the point decision. Leads to chaos.
Would be interesting to see how the final report dodges or dances to French aviation politics.
Decision makers, having studied the evidence before them must provide timely answers. Two years on, the community, the customers, the families all need answers. I have conducted complex air accident investigations as chairman, in which I grounded the relevant fleet pending certain fixes, whose implementation was completed in the same week the accident took place. A question of attitude, which leads to proper operations risk management (ORM). I haven't seen ORM mentioned here, odd.
I maintain that a fliable aircraft CFIT is the result of pilot performance. Evident in the last BEA report.
Perpignan isn't the only similar case, they are numerous and indicate a fundamental conceptual error in pilot-aircraft interface. No matter how many pilots like to fly Airbus aircraft, they too fail to see the major shortcomings in that design.
Anything else is technologist wording, not managerial straight to the point decision. Leads to chaos.
Would be interesting to see how the final report dodges or dances to French aviation politics.
Last edited by opherben; 24th Jun 2011 at 18:07.
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Black box flying
Many suppositions have been made about why these pilots didn't do the right thing.....but NOBODY, including the BEA has told us what they were looking at inside that black box( the cockpit) that stormy night...
Almost everyone has assumed that there were enough indications that gave the pilots the required info to make the right decision....when your cockpit is full of TV screens who can say what was being displayed /seen ...that even holds true for steam gauges...
And if half the displays say one thing and the other half say something opposite, which do you believe ....do you put more trust in airspeed than altimeters ?...
Now add to that the fact that there was the proverbial dark stormy night with no outside visual reference and probably ALOT of turbulence...
I think most of us who have do multiple SIM rides would agree that you can be led to make some erroneous choices when you lose all outside visual reference and maybe half your indicators (not that they have flags pop up ) but they don't agree with other info you're getting...
Add to that the fact that you've just had the aircraft change flight control modes/protections (ie aoa protect, auto trim etc) in the middle of this nightmarish 3 minute ride and I think we might lean toward a more questioning attitude of the designers who think they can cover every base with one of their control laws....
Almost everyone has assumed that there were enough indications that gave the pilots the required info to make the right decision....when your cockpit is full of TV screens who can say what was being displayed /seen ...that even holds true for steam gauges...
And if half the displays say one thing and the other half say something opposite, which do you believe ....do you put more trust in airspeed than altimeters ?...
Now add to that the fact that there was the proverbial dark stormy night with no outside visual reference and probably ALOT of turbulence...
I think most of us who have do multiple SIM rides would agree that you can be led to make some erroneous choices when you lose all outside visual reference and maybe half your indicators (not that they have flags pop up ) but they don't agree with other info you're getting...
Add to that the fact that you've just had the aircraft change flight control modes/protections (ie aoa protect, auto trim etc) in the middle of this nightmarish 3 minute ride and I think we might lean toward a more questioning attitude of the designers who think they can cover every base with one of their control laws....
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Turbine D: "As an engineer, we tend to think in terms of probabilities of failure, e.g., 10⁻⁹ or thereabouts, and designs are formulated and tested on a probability basis. What often is not thought of is "possibility" of failure. Possibilities are real."
That is very interesting. I work on prediction of response, or failure to respond (a.k.a. "resistance"), to anticancer drugs either in clinical development or approved by regulatory agencies and on the market (various tumor types). We look at various parameters (often called "biomarkers") that we think might have clinical utility in assessing risk. So we run stats on the data and come up with positive and negative predictive value, sensitivity, specificity, hazard ratios (with confidence intervals) and so on.
Like you in a sense, we are also interested in trying to understand and model or predict "failure", which in our case translates to progression of (usually metastatic) disease and death. In your case it's death by another means I suppose.
In coming up with models, you must have to assign different priorities or "weights" to the many different types of variable, no? I mean, all technical failures that can happen shouldn't be treated the same when trying to build a model I assume - or are they? Do you weight them differently, according to some estimate of criticality? I'm not a statistician but I run a fair bit of stats analysis for a living - sounds like you do as well. Sometimes you can't make real progress without some fairly heavy stats, at least in my experience.
That is very interesting. I work on prediction of response, or failure to respond (a.k.a. "resistance"), to anticancer drugs either in clinical development or approved by regulatory agencies and on the market (various tumor types). We look at various parameters (often called "biomarkers") that we think might have clinical utility in assessing risk. So we run stats on the data and come up with positive and negative predictive value, sensitivity, specificity, hazard ratios (with confidence intervals) and so on.
Like you in a sense, we are also interested in trying to understand and model or predict "failure", which in our case translates to progression of (usually metastatic) disease and death. In your case it's death by another means I suppose.
In coming up with models, you must have to assign different priorities or "weights" to the many different types of variable, no? I mean, all technical failures that can happen shouldn't be treated the same when trying to build a model I assume - or are they? Do you weight them differently, according to some estimate of criticality? I'm not a statistician but I run a fair bit of stats analysis for a living - sounds like you do as well. Sometimes you can't make real progress without some fairly heavy stats, at least in my experience.
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Would be interesting to see how the final report dodges or dances to French aviation politics.
