TAM A320 crash at Congonhas, Brazil
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Plane is on the ground.
The manual says:
-Automatic brakes don’t work? Use manual braking.
So why not this?
Pilot says "SPOILERS NOT UP!" after landing.
-Spoilers don’t work? Use manual deployment (move the air brake’s lever).
OR
-Spoilers don’t work? Use manual deployment AND command Autobrakes as well (it's an emergency situation isn't it?).
...
Engines disagree? Pilots can take care of that while this plane is loosing speed with the spoilers up and one of them is using foot brakes.
Is this too simplistic?
The manual says:
-Automatic brakes don’t work? Use manual braking.
So why not this?
Pilot says "SPOILERS NOT UP!" after landing.
-Spoilers don’t work? Use manual deployment (move the air brake’s lever).
OR
-Spoilers don’t work? Use manual deployment AND command Autobrakes as well (it's an emergency situation isn't it?).
...
Engines disagree? Pilots can take care of that while this plane is loosing speed with the spoilers up and one of them is using foot brakes.
Is this too simplistic?
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bomarc asked
and ELAC replied
The significant similar incidents appear to be 1998 Bacolod and 2004 Taipei-Sungshan. (America West in Phoenix was a case of mishandling thrust on rollout, after touchdown, so in this respect not similar.) All those four pilots are still alive. Ideally, one could talk to them a lot and try to find out more about their cognitive state. There is absolutely no information about that in either of the reports and yet it is crucial to understanding how thrust could be left above idle on touchdown, as well as how manual braking could be so delayed.
I have an acquaintance whose wife was on the Bacolod aircraft and who sent me the report. He said yesterday that he has corresponded with F/O Hernandez, who apparently maintains that it was a technical system failure, a "computer error". So it looks as if that avenue will not be as promising as one might have hoped.
PBL
PBL
why couldn't an experienced checkairman in the left seat stop the plane?
I don't know. I'll be looking to the investigators to find out and I hope they do a good job of exploring all avenues in the quest for why
I have an acquaintance whose wife was on the Bacolod aircraft and who sent me the report. He said yesterday that he has corresponded with F/O Hernandez, who apparently maintains that it was a technical system failure, a "computer error". So it looks as if that avenue will not be as promising as one might have hoped.
PBL
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Originally Posted by GearDown&Locked
So why not this?
Pilot says "SPOILERS NOT UP!" after landing.
-Spoilers don’t work? Use manual deployment (move the air brake’s lever).
Pilot says "SPOILERS NOT UP!" after landing.
-Spoilers don’t work? Use manual deployment (move the air brake’s lever).
And as has been said there already seems to be a modification (not confirmed) to alert the crew to the original mistake.
OR
-Spoilers don’t work? Use manual deployment AND command Autobrakes as well (it's an emergency situation isn't it?).
-Spoilers don’t work? Use manual deployment AND command Autobrakes as well (it's an emergency situation isn't it?).
Is this too simplistic?
In how many cases would it have helped?
Perhaps 3. As has been pointed out, about once in 17 million landings.
But in those cases the pilots had already made the grave errors of (a) not retarding both thrust levers and (b) not commencing manual braking immediately. It is hard to say if they would have remembered any other additional procedure if they neglected to to do the (from our perspective) obvious.
(Again, this is not to assign blame to the pilots, but just to wonder if the proposed modification would be effective).
On the other hand: Being able to deploy ground spoilers manually is also potentially disastrous, even if restricted to on-the-ground, e. g. during take-off or rejected landing.
To do an armchair-estimation and come up with a reliable figure of likelihood for these scenarios that is less than once in 17 million is impossible.
So it is doubtful that such a modification would improve the overall safety situation.
Bernd
PBL
Given that there is no such thing as an acceptable accident rate, especially to those involved, I agree that the investigators are really not going to be too interested in the A vs B issue. The 737 rudder hardovers were probably also statistically insignificant but rightly attracted massive effort (and dare one say, possibly encouraged by the location of the occurrences).
In the CGH case, I don't think anyone is suggesting that either overruns or TL mismanagement are significant issues on the millions of routine landings. The particular circumstance which is of concern is disablement of one TR and the apparent confusion caused. Try another statistic for "proportion of A320 overruns where one TR disabled" and I think you'll get a figure (at least 4 ex 7) which might suggest that action on the MEL & SB was sensible. No doubt AB's (& Boeings) will continue to overrun at a statistically insignificant rate, but hopefully no longer because of the confusion apparently caused by this particular deferred defect. Doubtless implementation will be accelerated because in this case there happpened to also be a cliff at the end of a short,wet runway.
Given that there is no such thing as an acceptable accident rate, especially to those involved, I agree that the investigators are really not going to be too interested in the A vs B issue. The 737 rudder hardovers were probably also statistically insignificant but rightly attracted massive effort (and dare one say, possibly encouraged by the location of the occurrences).
In the CGH case, I don't think anyone is suggesting that either overruns or TL mismanagement are significant issues on the millions of routine landings. The particular circumstance which is of concern is disablement of one TR and the apparent confusion caused. Try another statistic for "proportion of A320 overruns where one TR disabled" and I think you'll get a figure (at least 4 ex 7) which might suggest that action on the MEL & SB was sensible. No doubt AB's (& Boeings) will continue to overrun at a statistically insignificant rate, but hopefully no longer because of the confusion apparently caused by this particular deferred defect. Doubtless implementation will be accelerated because in this case there happpened to also be a cliff at the end of a short,wet runway.
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bubbers
Elac, I have responded several times saying I have never flown an Airbus
I have landed the B757 in TGU, Honduras on a 5400 ft runway at 3300 ft msl and had a reverser fail so just used single reverse with no problem
Actually, we don't really care, what your opinion is about the Airbus, admittedly, you don't know anything about it.
Soaringtheskies,
As a software-minded aviator I fully agree with you. Pilots do make faults (I do at least), computer designers produce code that does not meet all realities(I do at least). And you raised a further human factors issue that is really worth considering: the possible ranking problem.
Nearly 30 years back, on a dark december night, a Swiss Sata Caravelle managed to land on the dark sea instead of runway 06 of Funchal, Madeira. In the left seat was a seasoned captain who was paired with a much younger captain because the difficult non-precision approach during night time demanded an initial instruction and the younger one was current on this particular NDB approach.
The plane ditched on the base leg with the altimeters showing more than 500 feet. Obviously both pilots believed the other would have set QFE or QNH on the altimeters passing the transition altitude. And obviously the check-pilot did not question the procedures of his much more experienced "student". This is just one example of many where the rigid CRM of PF and PNF got mixed-up by an inverse non-formal relationship.
I dont want to put any blame on the crew, I am just scanning for human factors that could possibly make things happen like landing with one TL open.
As a software-minded aviator I fully agree with you. Pilots do make faults (I do at least), computer designers produce code that does not meet all realities(I do at least). And you raised a further human factors issue that is really worth considering: the possible ranking problem.
Nearly 30 years back, on a dark december night, a Swiss Sata Caravelle managed to land on the dark sea instead of runway 06 of Funchal, Madeira. In the left seat was a seasoned captain who was paired with a much younger captain because the difficult non-precision approach during night time demanded an initial instruction and the younger one was current on this particular NDB approach.
The plane ditched on the base leg with the altimeters showing more than 500 feet. Obviously both pilots believed the other would have set QFE or QNH on the altimeters passing the transition altitude. And obviously the check-pilot did not question the procedures of his much more experienced "student". This is just one example of many where the rigid CRM of PF and PNF got mixed-up by an inverse non-formal relationship.
I dont want to put any blame on the crew, I am just scanning for human factors that could possibly make things happen like landing with one TL open.
Last edited by clearedtocross; 8th Aug 2007 at 14:09.
Bring back the Dak!
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What the industry needs to decide is whether they are ultimately aiming for pilotless passenger aircraft or not. If yes, then presenting the pilot with T/L's not directly-correlated with thrust is but a small part of that progression. IMO, sitting there as a future mere observer while the computers perform the WHOLE flight is not a situation I would relish, and certainly not why I became a pilot in the first place, but...........
If the answer is no, then retaining T/L's which can be moved by the pilot, or motor-driven to be directly correlated with thrust at all times is a desirable factor. Why? Because, IMHO, in real-life every other speed-variable contrivance that the pilot has ever come across has always had a visible means of correlated control available to him/her. Since by definition under this option he/she will always be in the cockpit, why deprive him/her of an instantaneous witness of thrust-demand which can be readily seen?
I'm not against relevant enhancement of the soft/hardware to improve overall safety, but, where we are now in the scheme of things, IMHO non-moving and non-directly-correlated T/L's are an unnecessary step too far.
If the answer is no, then retaining T/L's which can be moved by the pilot, or motor-driven to be directly correlated with thrust at all times is a desirable factor. Why? Because, IMHO, in real-life every other speed-variable contrivance that the pilot has ever come across has always had a visible means of correlated control available to him/her. Since by definition under this option he/she will always be in the cockpit, why deprive him/her of an instantaneous witness of thrust-demand which can be readily seen?
I'm not against relevant enhancement of the soft/hardware to improve overall safety, but, where we are now in the scheme of things, IMHO non-moving and non-directly-correlated T/L's are an unnecessary step too far.
Last edited by ABUKABOY; 8th Aug 2007 at 12:48. Reason: Added words "and non" to make more sense, but it probably won't.
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If the answer is no, then retaining T/L's which can be moved by the pilot, or motor-driven to be directly correlated with thrust at all times is a desirable factor
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To aid all of us working from the same data, I have just posted the 1998 Bacolod and 2004 Taipei-Sungshan accident reports on the compendium at
http://www.rvs.uni-bielefeld.de/publ...ns/compendium/
Not pertinent here, maybe, but I have also added a section on the GOL 1907/ExcelAire midair, because we are worried about the criminalisation of accidents (of all types - we are worrying about the Maglev rail accident in Germany as well), and Jörn Stuphorn has performed a Why-Because Analysis from the available news reports which he presented at a workshop in May. Usually, one obtains guaranteed-reliable data, and as complete as possible, in order to construct the list of facts, but the human case seemed to us too pressing to wait in this case.
PBL
http://www.rvs.uni-bielefeld.de/publ...ns/compendium/
Not pertinent here, maybe, but I have also added a section on the GOL 1907/ExcelAire midair, because we are worried about the criminalisation of accidents (of all types - we are worrying about the Maglev rail accident in Germany as well), and Jörn Stuphorn has performed a Why-Because Analysis from the available news reports which he presented at a workshop in May. Usually, one obtains guaranteed-reliable data, and as complete as possible, in order to construct the list of facts, but the human case seemed to us too pressing to wait in this case.
PBL
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what does the next pilot do on a short wet runway, in the same kind of plane and something akin to brazil goes wrong?
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Sdruvss,
I would dearly like to respond, but it's off topic here. Instead, let me refer you to a talk at the Ninth Bieleschweig Workshop:
http://www.rvs.uni-bielefeld.de/Biel...inB9Slides.pdf
and maybe we could discuss privately or start a new thread.
PBL
I would dearly like to respond, but it's off topic here. Instead, let me refer you to a talk at the Ninth Bieleschweig Workshop:
http://www.rvs.uni-bielefeld.de/Biel...inB9Slides.pdf
and maybe we could discuss privately or start a new thread.
PBL
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Originally Posted by SoaringTheSkies
oh, and yes, Han Solo, it's really that simple. But there are times, when the brain just doesn't work that way. Sadly. Are those who get caught in those situations worse pilots than those who post how easy it would be in this thread?
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Thanks for the garbage tag, Han Solo. If you put the A320 in autothrust, you can put the T/L's in one of several detents, and listen to the engines and watch the guages as they vary their thrust depending on what is required of them, without the T/L's moving in sympathy. That is what post #1383 was all about. If you take the autothrust out and manually play with the throttles and they behave as "conventional" ones would, then bully for you. It was the operation in autothrust I was trying to comment on.
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Dreamland, I guess the point was not having to fight automation logic that won't give you ground spoilers until it senses all the inputs required and the pilot cannot override this logic on the A320.
I understand the FDR has two sensors to record TLA. Has it been verified by the FDR that both these sensors showed the TL above idle?
I understand the FDR has two sensors to record TLA. Has it been verified by the FDR that both these sensors showed the TL above idle?
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Hand Solo,
I would not want to make a guess if they were better or worse than anyone here. They did have a hell of a lot more experience than I have, hat much is for sure.
But: I'm not at all faulting anybody. I'm merely pointing out things that seem rather obvious to me.
So far, noone has given me a good explanation of what the advantages of the stationary thrust levers are. If there's a significant safety advantage, great. If there's none, then the slightest potential safety disadvantage should be a good reason to get rid of them again and put them into the drawer "things we've tried".
I guess the main point here is: it has to be allowed to reason over a specific system and come to a conclusion that it has advantages or disadvantages when compared to a different system. I couldn't care less who makes it. It's comparing two systems or rather design philosophies that happen to be obeyed by two different companies.
pj
I would not want to make a guess if they were better or worse than anyone here. They did have a hell of a lot more experience than I have, hat much is for sure.
But: I'm not at all faulting anybody. I'm merely pointing out things that seem rather obvious to me.
So far, noone has given me a good explanation of what the advantages of the stationary thrust levers are. If there's a significant safety advantage, great. If there's none, then the slightest potential safety disadvantage should be a good reason to get rid of them again and put them into the drawer "things we've tried".
I guess the main point here is: it has to be allowed to reason over a specific system and come to a conclusion that it has advantages or disadvantages when compared to a different system. I couldn't care less who makes it. It's comparing two systems or rather design philosophies that happen to be obeyed by two different companies.
pj
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Originally Posted by SoaringTheSkies
[...]
I'm not at all faulting anybody. I'm merely pointing out things that seem rather obvious to me.
So far, noone has given me a good explanation of what the advantages of the stationary thrust levers are. If there's a significant safety advantage, great. If there's none, then the slightest potential safety disadvantage should be a good reason to get rid of them again and put them into the drawer "things we've tried".
I guess the main point here is: it has to be allowed to reason over a specific system and come to a conclusion that it has advantages or disadvantages when compared to a different system. I couldn't care less who makes it. It's comparing two systems or rather design philosophies that happen to be obeyed by two different companies.
I'm not at all faulting anybody. I'm merely pointing out things that seem rather obvious to me.
So far, noone has given me a good explanation of what the advantages of the stationary thrust levers are. If there's a significant safety advantage, great. If there's none, then the slightest potential safety disadvantage should be a good reason to get rid of them again and put them into the drawer "things we've tried".
I guess the main point here is: it has to be allowed to reason over a specific system and come to a conclusion that it has advantages or disadvantages when compared to a different system. I couldn't care less who makes it. It's comparing two systems or rather design philosophies that happen to be obeyed by two different companies.
If it is obvious to you, then why not tell us exactly what it is?
To do away with things that have a "slight safety disadvantage" you have to come up with an alternative that is demonstrably safer. Can you? For that you'd first have to show that there actually is a problem. Then, that the new system doesn't have this problem. Then, that the new system does not introduce new problems.
Strangely enough, precisely those people that use the system every day, deny that there even is a problem.
For it be a real safety problem it would have to have been a causal factor in accidents. It hasn't been. Pilots neglecting to perform a very basic task has.
Here's one advantage I can think of. I stand corrected if it is just as easy with a moving-levers system:
It is very easy to limit one engine to a certain maximum power with A/THR active by setting the lever to that position. For example if it is causing excessive vibration or EGT upwards of a certain N1. When that keeps an engine from breaking apart due to excessive stresses caused by the vibration, while still being able to use the engine within its safe operating range, than it is even safety related. And this might happen more frequently than once every 17 million flights.
Bernd
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skallas,
Thanks for the further clarification of your ideas. My earlier comments were in part based on the apparent application of your idea to the proposed logic change suggested by GD&L which triggered my original response and which involved the automatic reduction in thrust on the thrust locked engine.
As to why the system does not now work as you propose, I don't know. Against the obvious scenarios it looks reasonable, but I have no idea what the non-obvious scenarios might be or how such a logic might work out depending on the failure modes involved. My guess, and it's just that, is that the deciding logic for why things are as they are might be like this:
Ground Spoilers not deployed when desired induces less increase in risk than Ground Spoilers deployed when not desired. One case involves a requirement for increased deceleration which is available by other means, but the other requires application of greater thrust and restored lift generation capacity which is not available by any other means.
So, the system (all engines running) requires 2 seperate valid inputs of pilot intent to extend the Ground Spoilers (Y+Y=Y), a single input isn't sufficient (Y+N=N). The failure cases (Y+?=N, ?+?=N) are designed to default to the more safe of the two alternatives given that the specifics of the failures could involve many possibilities where pilot intent might be either to stop or to go.
Where one might go with your idea is to propose an alternative second input to be used in the case where a TL input is discarded because the TL has not moved and Thrust Lock is active on that engine. Perhaps an input for brake pedal deflection could be used in place of the TL input.
There may be good reasons why this wouldn't work either but it would cross the bridge between your idea of discarding the Thrust Locked input and the need for two valid signals.
ELAC
(taking amateur aircraft designer hat off, because I reallly don't know for sure)
Thanks for the further clarification of your ideas. My earlier comments were in part based on the apparent application of your idea to the proposed logic change suggested by GD&L which triggered my original response and which involved the automatic reduction in thrust on the thrust locked engine.
As to why the system does not now work as you propose, I don't know. Against the obvious scenarios it looks reasonable, but I have no idea what the non-obvious scenarios might be or how such a logic might work out depending on the failure modes involved. My guess, and it's just that, is that the deciding logic for why things are as they are might be like this:
Ground Spoilers not deployed when desired induces less increase in risk than Ground Spoilers deployed when not desired. One case involves a requirement for increased deceleration which is available by other means, but the other requires application of greater thrust and restored lift generation capacity which is not available by any other means.
So, the system (all engines running) requires 2 seperate valid inputs of pilot intent to extend the Ground Spoilers (Y+Y=Y), a single input isn't sufficient (Y+N=N). The failure cases (Y+?=N, ?+?=N) are designed to default to the more safe of the two alternatives given that the specifics of the failures could involve many possibilities where pilot intent might be either to stop or to go.
Where one might go with your idea is to propose an alternative second input to be used in the case where a TL input is discarded because the TL has not moved and Thrust Lock is active on that engine. Perhaps an input for brake pedal deflection could be used in place of the TL input.
There may be good reasons why this wouldn't work either but it would cross the bridge between your idea of discarding the Thrust Locked input and the need for two valid signals.
ELAC
(taking amateur aircraft designer hat off, because I reallly don't know for sure)
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ELAC
One possible problem could be the continued take-off with uncommanded reverse on one engine scenario - pilot rudder input may lead to short brake application on one side .... would not want ground spoilers at that point! Perhaps one engine in TOGA input would override?
TP
One possible problem could be the continued take-off with uncommanded reverse on one engine scenario - pilot rudder input may lead to short brake application on one side .... would not want ground spoilers at that point! Perhaps one engine in TOGA input would override?
TP
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Criminalization
I suspect that this doesn´t belong to this thread but I can´t help but put in my two cents. First an interesting article about the Brazilian GOL accident and discusses criminalization:
http://www.salon.com/tech/col/smith/...13/index1.html
It seems to me that there is an worldwide tendency to decriminalize aviation accidents unless there is clear evidence for criminal behavior. This is to make all involved to become less defensive and to cooperate with the investigation that aims at understand what happened and preventing it from happeneing again. Please correct me if I am wrong.
I am impressed - and as a proud Brazilian - embarassed by how many people are involved in determining "the causes" of the TAM accident. The official agency for this is CENIPA, the Air Force organization that investigates accidents with the aim of preventing them. Even the officers at CENIPA say that the criminal investigations in the GOL and TAM accidents made their job more difficult. To make things more complicated, in Brazil it is the Air Force that administer that Air Traffic Control (equipments, software and people). Hence, it may be a little complicate to have the Air Force investiganting the Air Force...
About the TAM accident we have a lot of people involved. Besides CENIPA, we have two Committees (Senate and House) doing their own investigation (I believe only one congressman has some knowledge of aviation). Then there are the Federal and the Local Polices plus the
Attorney General and Minister of Defense (in the GOL accident I remember seeing the Defense Minister in TV talking about the causes of the accident a few days after it happened). Right now, CENIPA was collaborating with the House Committee (CPI) and they did bring the black boxes to clarify to the congressmen what they showed. Now, they decided not to do it any longer, among other things because France and the Airbus industry protested against CENIPA revealing the black boxes. So now the CPI is planning to have its own experts to tell them what the boxes show. They are planning to compare the black boxes of the landing in Congonhas with the landing in Porto Alegre in the same plane and crew just hours before.
All of this to say that I am not sure that this happens all over the world... Just not sure... Will listen if you all see this as pertinent to this thread.
http://www.salon.com/tech/col/smith/...13/index1.html
It seems to me that there is an worldwide tendency to decriminalize aviation accidents unless there is clear evidence for criminal behavior. This is to make all involved to become less defensive and to cooperate with the investigation that aims at understand what happened and preventing it from happeneing again. Please correct me if I am wrong.
I am impressed - and as a proud Brazilian - embarassed by how many people are involved in determining "the causes" of the TAM accident. The official agency for this is CENIPA, the Air Force organization that investigates accidents with the aim of preventing them. Even the officers at CENIPA say that the criminal investigations in the GOL and TAM accidents made their job more difficult. To make things more complicated, in Brazil it is the Air Force that administer that Air Traffic Control (equipments, software and people). Hence, it may be a little complicate to have the Air Force investiganting the Air Force...
About the TAM accident we have a lot of people involved. Besides CENIPA, we have two Committees (Senate and House) doing their own investigation (I believe only one congressman has some knowledge of aviation). Then there are the Federal and the Local Polices plus the
Attorney General and Minister of Defense (in the GOL accident I remember seeing the Defense Minister in TV talking about the causes of the accident a few days after it happened). Right now, CENIPA was collaborating with the House Committee (CPI) and they did bring the black boxes to clarify to the congressmen what they showed. Now, they decided not to do it any longer, among other things because France and the Airbus industry protested against CENIPA revealing the black boxes. So now the CPI is planning to have its own experts to tell them what the boxes show. They are planning to compare the black boxes of the landing in Congonhas with the landing in Porto Alegre in the same plane and crew just hours before.
All of this to say that I am not sure that this happens all over the world... Just not sure... Will listen if you all see this as pertinent to this thread.
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ELAC
One possible problem could be the continued take-off with uncommanded reverse on one engine scenario - pilot rudder input may lead to short brake application on one side .... would not want ground spoilers at that point! Perhaps one engine in TOGA input would override?
TP
One possible problem could be the continued take-off with uncommanded reverse on one engine scenario - pilot rudder input may lead to short brake application on one side .... would not want ground spoilers at that point! Perhaps one engine in TOGA input would override?
TP
You definitely would not want this as a take-off function. But if we follow skallas' idea that the logic would only be effective when we have a Thrust Lock condition, which by definition requires the affected TL to be in the CLB detent, then the case should not occur during take-off, only during landing. That said, an inadvertent movement of a TL into the CLB detent during take-off could be one of those non-obvious failure cases that would dictate against the logic.
ELAC