TAM 3054 Report released
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safetypee . . .What would this "slippery when wet, non grooved" 6360' (1939m) pavement have to do with this accident where neither the captain in the left seat, nor the captain in the right seat, had retarded both throttles and had left one throttle set at significant forward thrust during rollout?
This slippery-when-wet, non-grooved runway is within the operational envelope of the twin engined A320, with or without operating reversers . . . when proper landing technique is exercised...!
Thousands of landings in the rain had been made on this runway at this airport for many decades; even Trans Brasil would land with B727s in the rain many moons ago, when I was a pax.
This slippery-when-wet, non-grooved runway is within the operational envelope of the twin engined A320, with or without operating reversers . . . when proper landing technique is exercised...!
Thousands of landings in the rain had been made on this runway at this airport for many decades; even Trans Brasil would land with B727s in the rain many moons ago, when I was a pax.
Slippery when Wet
GB, the impression gained from the report was that both the airport management and operator only considered a ‘good’ wet runway or a contaminated runway; nothing in between. This provided them with a clear division for either operation or runway closure.
Such a view might have overlooked the importance of not having grooving on the ‘improved’ runway. The absence of grooving on a ‘good’ wet runway could reduce the friction to the low values seen when operating on flooded (contaminated) runways, but also there is a range of wet friction values short of being contaminated which would present a hazard. If this hazard had been identified, then even the ‘improved’ runway might have been closed in the conditions at the time of the accident.
Example calculations:
From the report, landing distance available (LDA) 1880 m 6170 ft,
From the report, the wet landing distance required (LDR) was 1332 m 4370 ft.
4370 ft wet / 1.92 = 2450 ft unfactored
With an approximation based on CRFI tables*, 4370 ft is equivalent to;
4400 ft on a wet runway (CRFI 0.5), ICAO ‘good’ braking action, or
5370 ft in heavy rain (CRFI 0.3), or
6180 ft in standing water (CRFI 0.2).
The latter exceeds the LDA.
If the standing water case had been considered (standing water not actually required, just a poor ‘wet’ surface), a reasonable choice particularly given the runway history, the non-validated runway improvements, and lack of grooving; then first, this could define the conditions as contaminated, which require reverse thrust, and second, the LDR is greater than the LDA.
*CRFI is not measured in wet conditions, but the tables in AC 164 provide excellent guidance; the wet correlation is taken from
‘wet runways’, AIR sect 1.6.5.
There had been many landings on the runway in wet conditions, but how wet was ‘wet’?
The report provides evidence of deteriorating runway conditions via pilot reports, which also suggest increasing reliance on thrust reverse to achieve certificated landing distances – a small, but significant and increasing deviation from the norm, which in some areas had become the ‘new norm’ – perhaps until the ATR accident the day before.
The runway improvements were not validated and the runway remained un-grooved. Thus there was no substantive justification for ‘upgrading the runway condition’, indeed IMHO (with hindsight), the original decision to allow wet operations vice a flooded runway was flawed, possibly due to a failure to consider the range of runway friction in wet conditions. Operators should note that friction is not the only factor for consideration – runway surface texture, tyre condition, rainfall rate, etc - Wet Runways. Also, see Hydroplaning of modern aircraft tires.
The point about ‘Slippery when Wet’ is that there appears to be no guidance as to what operators should do to account for the additional risk in landing on such runways. In this accident, there was a sound defense – close the runway, but due to circumstance, this defense was breached.
Such a view might have overlooked the importance of not having grooving on the ‘improved’ runway. The absence of grooving on a ‘good’ wet runway could reduce the friction to the low values seen when operating on flooded (contaminated) runways, but also there is a range of wet friction values short of being contaminated which would present a hazard. If this hazard had been identified, then even the ‘improved’ runway might have been closed in the conditions at the time of the accident.
Example calculations:
From the report, landing distance available (LDA) 1880 m 6170 ft,
From the report, the wet landing distance required (LDR) was 1332 m 4370 ft.
4370 ft wet / 1.92 = 2450 ft unfactored
With an approximation based on CRFI tables*, 4370 ft is equivalent to;
4400 ft on a wet runway (CRFI 0.5), ICAO ‘good’ braking action, or
5370 ft in heavy rain (CRFI 0.3), or
6180 ft in standing water (CRFI 0.2).
The latter exceeds the LDA.
If the standing water case had been considered (standing water not actually required, just a poor ‘wet’ surface), a reasonable choice particularly given the runway history, the non-validated runway improvements, and lack of grooving; then first, this could define the conditions as contaminated, which require reverse thrust, and second, the LDR is greater than the LDA.
*CRFI is not measured in wet conditions, but the tables in AC 164 provide excellent guidance; the wet correlation is taken from
‘wet runways’, AIR sect 1.6.5.
There had been many landings on the runway in wet conditions, but how wet was ‘wet’?
The report provides evidence of deteriorating runway conditions via pilot reports, which also suggest increasing reliance on thrust reverse to achieve certificated landing distances – a small, but significant and increasing deviation from the norm, which in some areas had become the ‘new norm’ – perhaps until the ATR accident the day before.
The runway improvements were not validated and the runway remained un-grooved. Thus there was no substantive justification for ‘upgrading the runway condition’, indeed IMHO (with hindsight), the original decision to allow wet operations vice a flooded runway was flawed, possibly due to a failure to consider the range of runway friction in wet conditions. Operators should note that friction is not the only factor for consideration – runway surface texture, tyre condition, rainfall rate, etc - Wet Runways. Also, see Hydroplaning of modern aircraft tires.
The point about ‘Slippery when Wet’ is that there appears to be no guidance as to what operators should do to account for the additional risk in landing on such runways. In this accident, there was a sound defense – close the runway, but due to circumstance, this defense was breached.
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Hi,
EASA Airworthiness Directive from 10 November 2010 (too late for 199 people)
http://henrimarnetcornus.20minutes-b...1930142838.pdf
EASA Airworthiness Directive from 10 November 2010 (too late for 199 people)
http://henrimarnetcornus.20minutes-b...1930142838.pdf
Within 48 months after the effective date of this AD, replace both FWC units with FWC P/N 350E053020909, in accordance with the instructions of Airbus SB A320-31-1334 Revision 02.
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Hi,
http://www.pprune.org/rumours-news/3...ml#post5625114
Fixed:
http://henrimarnetcornus.20minutes-b...1930142838.pdf
http://www.pprune.org/rumours-news/3...ml#post5625114
Originally Posted by Goldfish85
the "Retard" call should continue until both are at or near idle and the volume should increase first to "RETARD"" then to "PULL THEM BOTH BACK, DUMMY"
PJ2, would you agree with that quote ?
the "Retard" call should continue until both are at or near idle and the volume should increase first to "RETARD"" then to "PULL THEM BOTH BACK, DUMMY"
PJ2, would you agree with that quote ?
http://henrimarnetcornus.20minutes-b...1930142838.pdf
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I had missed that one :
Enhanced A320 logic to warn pilots of throttle retard oversight
Shame on the BEA to have never recommended the obvious.
What next with AF447 ... ?
Enhanced A320 logic to warn pilots of throttle retard oversight
The 'retard, retard' call-out will only stop if the pilot sets both throttle levers to idle, or sets one lever to idle and the other to reverse.
What next with AF447 ... ?
CONF iture;
PJ2, would you agree with that quote ?
No, not unconditionally. I think it is a response which parallels the right direction but should not be counted upon as a sole intervention.
First, I like very much what Safetypee has posted above. Second, I have offered thoughts on this throughout the thread including notions expressing the view that "not closing the throttles at landing" may be the outcome of a cognitive process of "out-thinking the airplane" when in fact no reason exists to do so. By that I mean, a pilot may hesitate in doing something he believes may be irreversible and doesn't fully understand the results of his actions. Where I think the process can cause such confusion is in the FCOM and the MEL of the time, which could have been more clear about what to do with a thrust lever for which engine had a reverser locked out. I recall reading it when I had the MEL item and wondering, do I leave the TL in IDLE or bring both into reverse? It was later clarified and both are brought into reverse but that was not always the case.
Regardless, nothing untoward would have occurred in either selection but by definition (by the incidents), that was not the understanding. Either that is the case, or some event surprised the PF such that he was momentarily unable to act. I have seen that as well, in the data and that was the comment when discussed. It happens, but not often enough to design warnings and software to cater to all untoward rabbit trails.
Now, all kinds of impressions (masquerading as 'understanding) could and have occurred on this and other A320 issues, not without understandable reasons, I will add. But early in the game of learning the airplane, it must be emphasized and accepted that "it is just an airplane". In defence of this assessment I offer two observations, which are, not surprisingly, related to the SATA (and other) hard landing events being discussed on that thread:
1) Why would a pilot expect anything different to occur other than a thrust reduction when a thrust lever was pulled back to IDLE? Was the concern, "what will happen if I bring both into reverse?
What other"devils on the wall" were painted about this and other systems that have no basis in how the aircraft actually functions? Is this merely a training issue or is there something else going on at the cognitive level that requires an "intellectualizing" of the airplane which subtlely displaces the "gestalt" we often speak of in how we normally fly airplanes? (Does automation drive out "art" or can the two co-exist? What part does training have in preserving the "art" while enhancing understanding?)
2) As partial evidence for this view, I offer the Aigle Azur A321 hard landing incident which occurred on January 08, 2008. The handling pilot, a captain, had voiced discomfort with sitting in the right seat. At landing, despite three 'retard' calls, the thrust levers were kept in the CLB detent until touchdown at 600fpm. The aircraft bounced 7ft, the PF selected the TLs to IDLE and the spoilers began to deploy. The 2nd t/d was at 850fpm, 3.3g's. The report, in French, is available here.
It is not a leap to envision the potential for a thrust lever of an engine which reverser has been locked out being kept in the CLB detent even after all the RETARD calls, as that is precisely what occurred here.
We will never know why, or what caused, in the sense of a cognitive "fixation" if I may call it that, the #2 thrust lever in the TAM cockpit to be left in its position while the other was dutifully retarded to idle. But the clues are available to know and to counter such human behaviours more effectively, and I do not believe, nor do I think that the present solution of "more" is the appropriate fix in terms of retard calls or whatever is to be conceived as the next counteractive measure to the next "cause", whatever it may be.
PJ2
Originally Posted by CONF iture
Originally Posted by Goldfish85
the "Retard" call should continue until both are at or near idle and the volume should increase first to "RETARD"" then to "PULL THEM BOTH BACK, DUMMY"
the "Retard" call should continue until both are at or near idle and the volume should increase first to "RETARD"" then to "PULL THEM BOTH BACK, DUMMY"
First, I like very much what Safetypee has posted above. Second, I have offered thoughts on this throughout the thread including notions expressing the view that "not closing the throttles at landing" may be the outcome of a cognitive process of "out-thinking the airplane" when in fact no reason exists to do so. By that I mean, a pilot may hesitate in doing something he believes may be irreversible and doesn't fully understand the results of his actions. Where I think the process can cause such confusion is in the FCOM and the MEL of the time, which could have been more clear about what to do with a thrust lever for which engine had a reverser locked out. I recall reading it when I had the MEL item and wondering, do I leave the TL in IDLE or bring both into reverse? It was later clarified and both are brought into reverse but that was not always the case.
Regardless, nothing untoward would have occurred in either selection but by definition (by the incidents), that was not the understanding. Either that is the case, or some event surprised the PF such that he was momentarily unable to act. I have seen that as well, in the data and that was the comment when discussed. It happens, but not often enough to design warnings and software to cater to all untoward rabbit trails.
Now, all kinds of impressions (masquerading as 'understanding) could and have occurred on this and other A320 issues, not without understandable reasons, I will add. But early in the game of learning the airplane, it must be emphasized and accepted that "it is just an airplane". In defence of this assessment I offer two observations, which are, not surprisingly, related to the SATA (and other) hard landing events being discussed on that thread:
1) Why would a pilot expect anything different to occur other than a thrust reduction when a thrust lever was pulled back to IDLE? Was the concern, "what will happen if I bring both into reverse?
What other"devils on the wall" were painted about this and other systems that have no basis in how the aircraft actually functions? Is this merely a training issue or is there something else going on at the cognitive level that requires an "intellectualizing" of the airplane which subtlely displaces the "gestalt" we often speak of in how we normally fly airplanes? (Does automation drive out "art" or can the two co-exist? What part does training have in preserving the "art" while enhancing understanding?)
2) As partial evidence for this view, I offer the Aigle Azur A321 hard landing incident which occurred on January 08, 2008. The handling pilot, a captain, had voiced discomfort with sitting in the right seat. At landing, despite three 'retard' calls, the thrust levers were kept in the CLB detent until touchdown at 600fpm. The aircraft bounced 7ft, the PF selected the TLs to IDLE and the spoilers began to deploy. The 2nd t/d was at 850fpm, 3.3g's. The report, in French, is available here.
It is not a leap to envision the potential for a thrust lever of an engine which reverser has been locked out being kept in the CLB detent even after all the RETARD calls, as that is precisely what occurred here.
We will never know why, or what caused, in the sense of a cognitive "fixation" if I may call it that, the #2 thrust lever in the TAM cockpit to be left in its position while the other was dutifully retarded to idle. But the clues are available to know and to counter such human behaviours more effectively, and I do not believe, nor do I think that the present solution of "more" is the appropriate fix in terms of retard calls or whatever is to be conceived as the next counteractive measure to the next "cause", whatever it may be.
PJ2
Last edited by PJ2; 3rd Mar 2011 at 21:14.
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I had missed that one :
Enhanced A320 logic to warn pilots of throttle retard oversight
Shame on the BEA to have never recommended the obvious.
What next with AF447 ... ?
Enhanced A320 logic to warn pilots of throttle retard oversight
Shame on the BEA to have never recommended the obvious.
What next with AF447 ... ?
I also remember the original thread containing a lot of warnings on the "folly" of non-moving thrust levers - something that was sadly rendered somewhat moot after the Turkish 737 accident at Schiphol.
PJ2 - as always, spot on. Not being a pilot I don't think I'm qualified to make a call as to whether automation interferes with the "art", but I do think that perception of the role automation plays has definitely become muddied by vested interests over the years. As a software engineer I'm painfully aware of the lengths one has to go to in order to protect against faults and fit as many use cases as can be defined.
If the "RETARD" annunciation was intended as a reminder rather than as defining the current configuration state (I suspect it was, but as has been said, this information was not well enough understood by airlines and line pilots), then I can understand the original design intent. However - with 20/20 hindsight it does appear something of a no-brainer.
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- October 18, 2004. Runway Overrun during landing On Taipei Sungshan Airport
- March 2006. ASC Safety Recommendation to Airbus Company : “Reviewing the design of stop mode of Retard warning sounds or accommodating other warning methods to ensure that the warning will continue before the thrust levers are pulled back to Idle notch after a touchdown has affirmed.”（ASC-ASR-06-03 –006). Airbus response : H2F3, ECAM alarm only. Not mandatory.
- July 17, 2007. Runway Overrun during landing at Sao Paulo-Congonhas (199 victims)
- November 10, 2010. EASA PAD : “need for improvements in the identification of throttle mis-positioning and so providing further opportunity for the flight crew to identify an incorrect thrust lever configuration and to correct this : « Enhanced RETARD logic »” (mandatory). « Do not install H2F3 »
Too late for 199 people.
- March 2006. ASC Safety Recommendation to Airbus Company : “Reviewing the design of stop mode of Retard warning sounds or accommodating other warning methods to ensure that the warning will continue before the thrust levers are pulled back to Idle notch after a touchdown has affirmed.”（ASC-ASR-06-03 –006). Airbus response : H2F3, ECAM alarm only. Not mandatory.
- July 17, 2007. Runway Overrun during landing at Sao Paulo-Congonhas (199 victims)
- November 10, 2010. EASA PAD : “need for improvements in the identification of throttle mis-positioning and so providing further opportunity for the flight crew to identify an incorrect thrust lever configuration and to correct this : « Enhanced RETARD logic »” (mandatory). « Do not install H2F3 »
Too late for 199 people.
Per Ardua ad Astraeus
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Anyone know what that means or contributes? Tombstone 101
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BOAC,
"The Tombstone Imperative" was a book on aviation safety written in the late '90s. I think it was written by one of the contributors to Channel 4's "Black Box" documentary, as it seemed to cover many of the same cases.
The title was derived from the opinion of a US official who stated that it seemed "[they] regulate by counting tombstones" - by which he meant that corrective actions and airworthiness directives only seemed to become urgent once enough people had died as a result of their not having been implemented yet.
"The Tombstone Imperative" was a book on aviation safety written in the late '90s. I think it was written by one of the contributors to Channel 4's "Black Box" documentary, as it seemed to cover many of the same cases.
The title was derived from the opinion of a US official who stated that it seemed "[they] regulate by counting tombstones" - by which he meant that corrective actions and airworthiness directives only seemed to become urgent once enough people had died as a result of their not having been implemented yet.
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Thank you DW - alles klar. A well-known judgement used in many spheres including rail, road and sea. How many people can we kill before someone notices.
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I'm working from memory here, so if anyone knows differently, please chime in - in the book, the author refers to regulatory authorities on occasion being too cosy with manufacturers and airlines - specifically that the US FAA was founded with two contradictory aims; to regulate the industry from a safety perspective and to promote aviation.
This latter aim came from a time when the fledgling manufacturers and airlines could conceivably be put out of business by compensation arising from a single accident. The book argues that the latter aim should have been dropped years ago, as both manufacturers and airlines are now million- or billion-dollar entities that no longer require government protection.
This latter aim came from a time when the fledgling manufacturers and airlines could conceivably be put out of business by compensation arising from a single accident. The book argues that the latter aim should have been dropped years ago, as both manufacturers and airlines are now million- or billion-dollar entities that no longer require government protection.
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I´ve written a study on landing excursions where the aforementioned "cognitive fixation" and TAM3054 are covered in detail.
In short, there´s more happening in our brains than meets the eye.
Please feel free to download it from http://dl.dropbox.com/u/6109264/study.pdf.
In short, there´s more happening in our brains than meets the eye.
Please feel free to download it from http://dl.dropbox.com/u/6109264/study.pdf.
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Originally Posted by magelan
I´ve written a study on landing excursions where the aforementioned "cognitive fixation" and TAM3054 are covered in detail.
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It's defintiely good stuff - If you ever extend or re-publish I reckon an interesting addition would be to compare and contrast AF358 with AA1420 at Little Rock - the common element being rapid changes in weather and time pressures causing the pilots to make poor (in hindsight) decisions and miss things (arming the spoilers in the case of the latter).
Last edited by DozyWannabe; 4th Mar 2011 at 20:20.
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Yes, the Little Rock accident is an interesting (and very well researched) event, however, it is also a classic case of an unstabilized approach - very much in contrast to the Air France accident in Toronto. And that is one of my key points: the importance of stabilized approach criteria has been somewhat overstated at the expense of research into the human factor dynamics of the flare and touchdown phase ("beyond the threshold"). Good approaches have led to bad landings as much as bad approaches have led to good landings.
Fortunately from an academic standpoint, less so from a pilot´s perspective, there is no shortage of "accident material" for further research.
Thanks for the kind comments...
Fortunately from an academic standpoint, less so from a pilot´s perspective, there is no shortage of "accident material" for further research.
Thanks for the kind comments...
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You make a good point, and I hope I didn't come across as presumptuous!
I guess the valid conclusion that can be drawn from comparing and contrasting those two incidents is that even with a stabilised approach phase things can go wrong - if the received wisdom has tended to support the notion that a stabilised approach will always help in that situation, then AF358 would tend to contradict that notion. Which supports your argument quite neatly.
I guess the valid conclusion that can be drawn from comparing and contrasting those two incidents is that even with a stabilised approach phase things can go wrong - if the received wisdom has tended to support the notion that a stabilised approach will always help in that situation, then AF358 would tend to contradict that notion. Which supports your argument quite neatly.
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PJ2
I don't see it either as the sole solution. You prone more training, so do I.
As the system is much more complex that the manufacturer wanted it to be, only regular additional training can help a crew to fully assimilate its functioning in details.
But when a specific aircraft type leaves the pavement for the third time, and so for the same reason, in terms of aviation safety, such rabbit trail is called les Champs Élysées, and serious attention is needed.
DozyWannabe
That's correct, but as Airbus choose to put one, they need to go to the end of their logic and don't stop the reminder as long as the demand is not fulfilled, especially when the consequences can and have been tragic.
Thanks for the resume on the book, I didn't know that one.
magelan
Thanks for the link, that's interesting reading.
Concerning the TAM accident, please take note that the following is not exact :
The RETARD callout ceased as soon as the ENG1 THR LVR was selected to REV but the other THR LVR was still in the CLB detent.
The newer FWC version was not the awaited Enhanced RETARD logic, but a useless additional ECAM warning msg.
I don't see it either as the sole solution. You prone more training, so do I.
As the system is much more complex that the manufacturer wanted it to be, only regular additional training can help a crew to fully assimilate its functioning in details.
But when a specific aircraft type leaves the pavement for the third time, and so for the same reason, in terms of aviation safety, such rabbit trail is called les Champs Élysées, and serious attention is needed.
I've always been under the impression that your view was that a pilot should not rely on computers to that degree, and that they should know to reduce thrust without the need for an audible reminder.
That's correct, but as Airbus choose to put one, they need to go to the end of their logic and don't stop the reminder as long as the demand is not fulfilled, especially when the consequences can and have been tragic.
Thanks for the resume on the book, I didn't know that one.
magelan
Thanks for the link, that's interesting reading.
Concerning the TAM accident, please take note that the following is not exact :
Unfortunately, the Flight Warning Computer ceased its “retard” call-out as soon as thrust lever no.1 was at idle (a newer FWC version, offered as an option by Airbus but not bought by TAM, only ceased its “retard” call-out when both thrust levers were retarded to idle).
The newer FWC version was not the awaited Enhanced RETARD logic, but a useless additional ECAM warning msg.
