TAM A320 crash at Congonhas, Brazil
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As NoD alludes to above it is more likely that the A320 was certified to operate with no reversers and their availability is a bonus. The 737 BOAC flies is based on a 40 year old design and may have required reversers to effect a stop in the 1960's. The current incarnation of the design may still be able to rely on the reversers for stopping power due to historical 'grandfather' rights whereas the more modern 320 must demonstrate it's stopping ability on brakes alone.
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I understand they are planning to build a steel net in both ends of the runway in Congonhas. Also soft cement as a escape.
The "net" really intrigues me, however, and I'd like to know more about this scheme, if it's anything more than someone's blue skies idea. Active? Passive? It seems like it could cause as many problems as it might solve.
Does anybody really think having a net at the end of 35L would have changed much? I believe it might have saved some folks on the ground, but maybe not even that. IIRC, the TAM flight exited the runway to the left prior to the threshhold.
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when you have an airport with a shear drop on both ends, a horizontal net might make some sense. certainly not a vertical net...like the "barrier" on some carriers.
while not intended for the job, the approach lighting pier at KLGA supported a 737-400 which went off the runway and would surely have ended up in the bay were it not for the above.
while not intended for the job, the approach lighting pier at KLGA supported a 737-400 which went off the runway and would surely have ended up in the bay were it not for the above.
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If we are going to nets, horizontal or vertical, to stop airplanes from going off the end of runways I think first we need to let the pilots get it down to 30 knots or so before going off, not 90+. I won't say it again so find a way to let a runaway airplane be controlled by pilot input.
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Decisions
Tam has decided:
To buy the new software with prolonged warning (light and sound) to pilots when one TL is on forward and the other in REV. (US$5000.00)
to install in all A-320
Not to land in Congonhas with one reverser locked up
The Infraero is deciding:
The steel net
The grooving will finish on September 8
Congonhas no longer will be a rub
Less flights to Congonhas
Soft cement at the ends
Perhaps privatize some or all airports
The Minister of Defense
No longer talking about a new airport
Will divert Congonhas flights to Guarulhos and Campinas.
Will work on both these sirports to accomodate the traffic and passengers (the longer runway in Guarulhos is going to be reccaped)
Wants less passenger in the planes with more distance between the seats
Will talk with the controllers who want to be heard
The Air Force
I guess will continue to administer Air Traffic Control although there has been talks to make it civilian. Will receive more money from the Federal Government.
And so on...
To buy the new software with prolonged warning (light and sound) to pilots when one TL is on forward and the other in REV. (US$5000.00)
to install in all A-320
Not to land in Congonhas with one reverser locked up
The Infraero is deciding:
The steel net
The grooving will finish on September 8
Congonhas no longer will be a rub
Less flights to Congonhas
Soft cement at the ends
Perhaps privatize some or all airports
The Minister of Defense
No longer talking about a new airport
Will divert Congonhas flights to Guarulhos and Campinas.
Will work on both these sirports to accomodate the traffic and passengers (the longer runway in Guarulhos is going to be reccaped)
Wants less passenger in the planes with more distance between the seats
Will talk with the controllers who want to be heard
The Air Force
I guess will continue to administer Air Traffic Control although there has been talks to make it civilian. Will receive more money from the Federal Government.
And so on...
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EMAS
Engineered Material Arresting System (EMAS)
In the USA, the FAA requires that commercial airports, regulated under Part 139 safety rules, have a standard Runway Safety Area (RSA) where possible. At most commercial airports the RSA is 500 feet wide and extends 1000 feet beyond each end of the runway. The FAA has this requirement in the event that an aircraft overruns, undershoots, or veers off the side of the runway. The most dangerous of these incidents are overruns, but since many airports were built before the 1000-foot RSA length was adopted some 20 years ago, the area beyond the end of the runway is where many airports cannot achieve the full standard RSA. This is due to obstacles such as bodies of water, highways, railroads, and populated areas or severe drop-off of terrain.
The FAA has a high-priority program to enhance safety by upgrading the RSAs at commercial airports and provide federal funding to support those upgrades. However, it still may not be practical for some airports to achieve the standard RSA. The FAA, knowing that it would be difficult to achieve a standard RSA at every airport, began conducting research in the 1990s to determine how to ensure maximum safety at airports where the full RSA cannot be obtained. Working in concert with the University of Dayton, the Port Authority of New York and New Jersey, and the Engineered Arresting Systems Corporation (ESCO) of Logan Township, NJ, a new technology emerged to provide an added measure of safety. An Engineered Materials Arresting System (EMAS) uses materials of closely controlled strength and density placed at the end of a runway to stop or greatly slow an aircraft that overruns the runway. The best material found to date is a lightweight, crushable concrete. When an aircraft rolls into an EMAS arrestor bed, the tires of the aircraft sink into the lightweight concrete and the aircraft is decelerated by having to roll through the material.
Benefits of the EMAS Technology
The EMAS technology provides safety benefits in cases where land is not available, where it would be very expensive for the airport sponsor to buy the land off the end of the runway, or where it is otherwise not possible to have the standard 1,000-foot overrun. This technology is now in place at 18 airports with installation under contract at six additional airports. A standard EMAS installation extends 600 feet from the end of the runway. An EMAS arrestor bed can still be installed to help slow or stop an aircraft that overruns the runway, even if less than 600 feet of land is available.
Current FAA Initiatives
The Office of Airports prepared an RSA improvement plan for the runways at approximately 575 commercial airports in 2005. This plan allows the agency to track the progress and to direct federal funds for making all practicable improvements, including the use of EMAS technology.
Presently, the EMAS system developed by ESCO using crushable concrete is the only system that meets the FAA standard. However, FAA is conducting research through the Airport Cooperative Research Program (project number 07-03) that will examine alternatives to the existing approved system. The results of this effort are expected in 2009. More information on the project can be found at the Transportation Research Board website at http://www.trb.org/CRP/ACRP/ACRP.asp.
EMAS Arrestments
To date, there have been four incidents where the technology has worked successfully to keep aircraft from overrunning the runway and in several cases has prevented injury to passengers and damage to the aircraft.
May 1999: A Saab 340 commuter aircraft overran the runway at JFK
May 2003: Gemini Cargo MD-11 was safely decelerated at JFK
January 2005: A Boeing 747 overran the runway at JFK
July 2006: Mystere Falcon 900 airplane ran off the runway at the Greenville Downtown Airport in South Carolina
EMAS Installations
Currently, EMAS is installed at 24 runway ends at 19 airports in the United States. With plans to install 12 additional EMAS systems at seven more U.S. airports.
In the USA, the FAA requires that commercial airports, regulated under Part 139 safety rules, have a standard Runway Safety Area (RSA) where possible. At most commercial airports the RSA is 500 feet wide and extends 1000 feet beyond each end of the runway. The FAA has this requirement in the event that an aircraft overruns, undershoots, or veers off the side of the runway. The most dangerous of these incidents are overruns, but since many airports were built before the 1000-foot RSA length was adopted some 20 years ago, the area beyond the end of the runway is where many airports cannot achieve the full standard RSA. This is due to obstacles such as bodies of water, highways, railroads, and populated areas or severe drop-off of terrain.
The FAA has a high-priority program to enhance safety by upgrading the RSAs at commercial airports and provide federal funding to support those upgrades. However, it still may not be practical for some airports to achieve the standard RSA. The FAA, knowing that it would be difficult to achieve a standard RSA at every airport, began conducting research in the 1990s to determine how to ensure maximum safety at airports where the full RSA cannot be obtained. Working in concert with the University of Dayton, the Port Authority of New York and New Jersey, and the Engineered Arresting Systems Corporation (ESCO) of Logan Township, NJ, a new technology emerged to provide an added measure of safety. An Engineered Materials Arresting System (EMAS) uses materials of closely controlled strength and density placed at the end of a runway to stop or greatly slow an aircraft that overruns the runway. The best material found to date is a lightweight, crushable concrete. When an aircraft rolls into an EMAS arrestor bed, the tires of the aircraft sink into the lightweight concrete and the aircraft is decelerated by having to roll through the material.
Benefits of the EMAS Technology
The EMAS technology provides safety benefits in cases where land is not available, where it would be very expensive for the airport sponsor to buy the land off the end of the runway, or where it is otherwise not possible to have the standard 1,000-foot overrun. This technology is now in place at 18 airports with installation under contract at six additional airports. A standard EMAS installation extends 600 feet from the end of the runway. An EMAS arrestor bed can still be installed to help slow or stop an aircraft that overruns the runway, even if less than 600 feet of land is available.
Current FAA Initiatives
The Office of Airports prepared an RSA improvement plan for the runways at approximately 575 commercial airports in 2005. This plan allows the agency to track the progress and to direct federal funds for making all practicable improvements, including the use of EMAS technology.
Presently, the EMAS system developed by ESCO using crushable concrete is the only system that meets the FAA standard. However, FAA is conducting research through the Airport Cooperative Research Program (project number 07-03) that will examine alternatives to the existing approved system. The results of this effort are expected in 2009. More information on the project can be found at the Transportation Research Board website at http://www.trb.org/CRP/ACRP/ACRP.asp.
EMAS Arrestments
To date, there have been four incidents where the technology has worked successfully to keep aircraft from overrunning the runway and in several cases has prevented injury to passengers and damage to the aircraft.
May 1999: A Saab 340 commuter aircraft overran the runway at JFK
May 2003: Gemini Cargo MD-11 was safely decelerated at JFK
January 2005: A Boeing 747 overran the runway at JFK
July 2006: Mystere Falcon 900 airplane ran off the runway at the Greenville Downtown Airport in South Carolina
EMAS Installations
Currently, EMAS is installed at 24 runway ends at 19 airports in the United States. With plans to install 12 additional EMAS systems at seven more U.S. airports.
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Paxboy - I believe you are correct. I have no access to any AB perf figures and it would have been more constructive of NOD and CM to have offered such information rather than reacting in the instant 'AB Defence' mode when no attack was made. Whether or not I fly a canvas covered 737, I am trying to caution against the OVERALL impression that has appeared often here that T/Rs are 'irrelevant' - that may be so for the AB family but it is certainly not irrelevant for many other types. As quoted before, on anything other than dry runways, my 737 QRP LDRs are based on 2 reversers at 'No 2 detent' (around 70%N1). I again reiterate that you will NOT easily stop any aeroplane on braking action 'poor' with wheelbrakes alone. Without T/Rs, in the presence of aquaplaning or an otherwise slippery surface, there is a severe risk of 'going off the end'. Indeed NOD quotes BA's figures as a 24% increase in LDR with no reversers on a slippery runway (but does not specify the level of reverse
). That would certainly knacker a BA 320 in CGH on a slippery runway. I see another operator quotes 23%.
So the message for all is to make sure you have read the 'small print' in your performance tables regarding reverse, and thought SERIOUSLY about runway surface/braking action and how you expect to retard the beast before you plant your a/c on it, especially if the ba is nil to poor.
PS NOD - there are no 'grandfather' rights involved for the 737-700 LDRs. It is indeed a 'new 'certification' and
No sir, in the "60's" the Classic was certified to stop without reversers. It was the introduction of the NG which produced LDRs WITH reverse. That is an important message for 737 NG drivers if no-one else.
). That would certainly knacker a BA 320 in CGH on a slippery runway. I see another operator quotes 23%.So the message for all is to make sure you have read the 'small print' in your performance tables regarding reverse, and thought SERIOUSLY about runway surface/braking action and how you expect to retard the beast before you plant your a/c on it, especially if the ba is nil to poor.
PS NOD - there are no 'grandfather' rights involved for the 737-700 LDRs. It is indeed a 'new 'certification' and
Originally Posted by Carnage Matey!
The 737 BOAC flies is based on a 40 year old design and may have required reversers to effect a stop in the 1960's.
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BOAC
Not so - I quoted a 24% decrease with 2 "Revs Operative". Since we are talking "absolute minimum LDR" we can safely assume "full reverse" 
A 24% decrease equates to a 31.5% increase.
I did say maybe, since there are many areas the 737 is still a 1960s design apparently for certification - or at least Boeing ask for it:
at http://www.flug-revue.rotor.com/frhe...11/FR9611b.htm
I still think we are on a red herring over LDR There is no performance data available for 1 Eng in Reverse, 1 Eng at nearly Climb Power (Fwd), no GS, delayed braking etc. for obvious reasons
NOD quotes BA's figures as a 24% increase in LDR with no reversers on a slippery runway (but does not specify the level of reverse).
A 24% decrease equates to a 31.5% increase.
PS NOD - there are no 'grandfather' rights involved for the 737-700 LDRs.
Brown also points out that Boeing's product strategy is really questionable when it comes to the certification of its new airliners: "A new aircraft design should meet the safety requirements of the time. Derivatives of older aircraft usually only required the implication of new regulations if major changes to the design were made. Other than that, the old law from the time of the first certification applied. While our competitor does not miss an opportunity to promote the alleged modern high-tech design of its new 737 generation, Boeing is more then eager to claim the "grandfather's rights" of the very first 737 for its newest product-line. The basic 737 was certified in 1967 according to annex 15 of the federal airworthiness directives. Numerous safety requirements were added in the following 20 years, according to which the A320 was certified in 1988 (annex 56). Now, another ten years later, Boeing is demanding the certification according to the 30 year old derivative rights for the new 737, even though it has larger wings, another structure, new high-lift devices, new engines, a new empenage, a new landing gear, a new electrical system, as well as, significantly modified fuselage sections, entirely new avionics, and a new cockpit. Although Boeing is asking for 15 exemption to the total of 377 sections of the current regulations, exactly these 15 points, in my point of view, are a major concern to flight safety."
According to Brown, Boeing is trying to gain a competitive advantage against Airbus by asking for the 1967 standards for the cabin doors and the emergency evacuation system, which gives the 737-800, as the largest member of the new 737 family, a capacity of 189 seats. This is nine more seats than the A320 can offer, which has larger exits according to the newest regulations.
Furthermore, Boeing wants an exemption for the required accelerate stop distance, which would give the Seattle product a significant advantage in take-off performance.
The demands of the US company even include "relaxed" criteria concerning the damage tolerance limits and the demand to keep the old cabin pressure decompression system, although Boeing plans a higher cruise altitude for the new 737.
For Brown, these are only a few examples for Boeing's dubious product philosophy. Other points concern the resistance against higher inertial forces during emergency landings, the design of the flight control system, warning systems, and the general design of the safety systems. In all of these points the A320 had to adhere to the new regulations, while Boeing is willing to accept outdated safety standards to gain a competitive advantage.
"The catalogue of exemptions mounts in the birdstrike regulations While all modern airliner must be able to return safely to the ground after the stabilizer has been hit by an eight pound bird, Boeing is asking to be released from this regulation", Brown gets worked up.
According to Brown, Boeing is trying to gain a competitive advantage against Airbus by asking for the 1967 standards for the cabin doors and the emergency evacuation system, which gives the 737-800, as the largest member of the new 737 family, a capacity of 189 seats. This is nine more seats than the A320 can offer, which has larger exits according to the newest regulations.
Furthermore, Boeing wants an exemption for the required accelerate stop distance, which would give the Seattle product a significant advantage in take-off performance.
The demands of the US company even include "relaxed" criteria concerning the damage tolerance limits and the demand to keep the old cabin pressure decompression system, although Boeing plans a higher cruise altitude for the new 737.
For Brown, these are only a few examples for Boeing's dubious product philosophy. Other points concern the resistance against higher inertial forces during emergency landings, the design of the flight control system, warning systems, and the general design of the safety systems. In all of these points the A320 had to adhere to the new regulations, while Boeing is willing to accept outdated safety standards to gain a competitive advantage.
"The catalogue of exemptions mounts in the birdstrike regulations While all modern airliner must be able to return safely to the ground after the stabilizer has been hit by an eight pound bird, Boeing is asking to be released from this regulation", Brown gets worked up.
I still think we are on a red herring over LDR
There is no performance data available for 1 Eng in Reverse, 1 Eng at nearly Climb Power (Fwd), no GS, delayed braking etc. for obvious reasons
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OK - 31.5% even worse without. QED?
I do not agree that LDR is irrelevant. If we are to believe the 'story' of the same a/c the day before, which, landing 500' 'early', only just stopped at the end, the a/c was probably operating OUTSIDE LDR for the runway condition.
Can we please drop the 'Boeing certification' issue? It is even less relevant in this thread and I only responded to correct the errors made. By all means start an anti-Boeing thread elsewhere.
I do not agree that LDR is irrelevant. If we are to believe the 'story' of the same a/c the day before, which, landing 500' 'early', only just stopped at the end, the a/c was probably operating OUTSIDE LDR for the runway condition.
Can we please drop the 'Boeing certification' issue? It is even less relevant in this thread and I only responded to correct the errors made. By all means start an anti-Boeing thread elsewhere.
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NigelOnDraft . . .
". . . the 737-800, as the largest member of the new 737 family, a capacity of 189 seats. This is nine more seats than the A320 can offer, which has larger exits according to the newest regulations.
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NigelOnDraft :
flyer145 / Lemurian / Quote:
What Lemurian said is quite correct. The autobrake was not providing the decleration that was set/required! You are also correct that the autobrake could have been working but because of a slippery runway could not provide the required deceleration. However the "NO DECEL" is a standard call and was missed out! Maybe the announcement of "No spoilers" & "No decel" would have woken the PF to the real reason or prompted him to go-around.
I trust the criticisms you make of deceased pilots is made from 100% knowing this call is a TAM SOP requirement
That call is NOT an SOP in BA for instance...
-------------------------------------------------
Nigel, thank you, that was actually my point cos neither was it an SOP call in my previous airline! Except if judging by all clues you would judge a real decel problem; in that case of course it would be mandatory to call it out. But this has not only to do with the green light coming on or not.
To my opinion, the crew made adequate call outs as they stated "no spoilers" and a "NO DECEL" call by calling "decelerate, decelerate!". I don't know their SOP's either...
You'll all probably agree that the call out's seems at least very CLEAR to both of them and that other calls wouldn't have changed much here: the crew rapidly understood it was ALL GOING VERY WRONG.
They were faced with something they did not understand : LDG all GREEN which means all the required systems are working normally and then no spoilers and no deceleration on this bloody short and slippery runway !!!!!!!
Easy to analyse afterwards, it will probably be... but let's not jump to conclusions and let's wait the specialists final report.
flyer146 (not 145 nigel, unfortunately if you see what I mean!
)
flyer145 / Lemurian / Quote:
What Lemurian said is quite correct. The autobrake was not providing the decleration that was set/required! You are also correct that the autobrake could have been working but because of a slippery runway could not provide the required deceleration. However the "NO DECEL" is a standard call and was missed out! Maybe the announcement of "No spoilers" & "No decel" would have woken the PF to the real reason or prompted him to go-around.
I trust the criticisms you make of deceased pilots is made from 100% knowing this call is a TAM SOP requirement
That call is NOT an SOP in BA for instance...
-------------------------------------------------
Nigel, thank you, that was actually my point cos neither was it an SOP call in my previous airline! Except if judging by all clues you would judge a real decel problem; in that case of course it would be mandatory to call it out. But this has not only to do with the green light coming on or not.
To my opinion, the crew made adequate call outs as they stated "no spoilers" and a "NO DECEL" call by calling "decelerate, decelerate!". I don't know their SOP's either...
You'll all probably agree that the call out's seems at least very CLEAR to both of them and that other calls wouldn't have changed much here: the crew rapidly understood it was ALL GOING VERY WRONG.
They were faced with something they did not understand : LDG all GREEN which means all the required systems are working normally and then no spoilers and no deceleration on this bloody short and slippery runway !!!!!!!
Easy to analyse afterwards, it will probably be... but let's not jump to conclusions and let's wait the specialists final report.
flyer146 (not 145 nigel, unfortunately if you see what I mean!
)
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Two Points
Soft cement at the ends?
Does this mean the runway will be shorter?
Does this mean the runway will be shorter?
Insofar as number of passengers for the A320 I did a research in all companies flying the A320 and the vast majority fly with 150-5 passengers.
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Indeed NOD quotes BA's figures as a 24% increase in LDR with no reversers on a slippery runway (but does not specify the level of reverse). That would certainly knacker a BA 320 in CGH on a slippery runway. I see another operator quotes 23%.
You are confusing your terms. NOD did not quote BA figures as saying there was a 24% increase in landing distance on a slippery runway, what he wrote was:
BA QRH A320 IAE 2 Rev Operative, Max Manual Braking, improves LDR from 50' by 5% (Dry) to 24% Ice over no Rev.
The numbers you quoted for the B737:
The Boeing 737-700 requires an additional 370m for braking action 'Poor' with 1 u/s and 970m for both, which is far from 'little effect'.
A wet runway, which was what was reported at CGH (albeit with the modifier "slippery" which has an unknown value) is described in terms of its effect on performance by Airbus as "A runway is considered wet when the surface has a shiny appearance due to a thin layer of water. When this layer does not exceed 3mm in depth, there is no substantial risk of hydroplaning." (FCOM 2.04.10 P1). A wet runway is one where the friction coefficient is .40 or greater and is analogous to a braking action report of "Good".
Though we'll have to wait for the completion of the investigation to know for sure, previous discussions regarding the effect of reverse on stopping distance have been predicated on the runway condition being as it was reported by the tower, i.e. wet but not contaminated. If it turns out that this was not the case in reality then the calculations are not relevant, and a prime question would become why the surface was below the stated condition when it had apparently been tested only minutes before the accident. Obviously, if the runway was contaminated with significant standing water then the case for making any landing at all there that night becomes open to question.
Referring to your post it's a bit unclear, but if the figures you quote are coming from the B737 MEL they would likely relate to additives to RLD which is a factored value. Quite possibly the additives are factored as well as, in that they are additives implies that the use of reverse was considered in the original calculation of RLD for this aircraft. Quite possibly the effect of reverse on the published ALD values is less, but not having a B737 manual at hand I don't know.
On the Airbus I think the documentation bias is to the conservative side. The figures published for both RLD and ALD under any runway condition do not take any credit into account for reverse, so the numbers are valid for a stop made with both engines providing forward idle thrust. From the ALD values a decrement is then provided to account for the use of both reversers, should you wish to consider their use. As it's a decrement, the lower the percentage value the more conservative the estimated effect of reverse. For the airplane I fly the range is from -2% to -7% for 2 reversers operative in all cases except the "Icy" condition (coeff. = .05!) where the value is 19%. Possibly the actual effect of reverse thrust on the landing distance may be slightly greater, but if so that’s an unplanned bonus to stopping distance and not the opposite.
Going through Airbus’ performance document “Getting to Grips With Aircraft Performance” I also came across the following statement:
"In other words, the aquaplaning speed is a threshold at which friction forces are severely diminished. Performance calculations on contaminated runways take into account the penalizing effect of hydroplaning." 5.5.2.4 Page 82
The particular sentence was included in a section of the document discussing aquaplaning and its effect on takeoff performance, but I suspect that the statement is equally valid for landing performance calculations, which aren’t generally as limiting in the first place. So, when you look at the factors relating to the effect of reverse thrust on Airbus stopping distances what you are seeing is a value to which it is quite likely a greater degree of conservatism has been applied than may be the case with the B737 numbers you quoted.Also, while looking into Airbus' recommended braking techniques on another matter I came upon the following in the FCTM which might help explain how the general effect of reverse thrust is considered from a performance perspective and why in a previous post I referred to the effect of one reverser below 100 kts as being negligible:
THRUST REVERSERS
Thrust reverser efficiency is proportional to the square of the speed. So, it is recommended to use reverse thrust at high speeds.
Pull to reverse IDLE at main landing gear touchdown (not before). When REV is indicated in green on ECAM, MAX reverse may be applied.
The maximum reverse thrust is obtained at N1 between 70% and 85% and is controlled by the FADEC. Below 70 kts, reversers efficiency decreases rapidly, and below 60 kts with maximum reverse selected, there is a risk of engine stall. Therefore, it is recommended to smoothly reduce the reverse thrust to idle at 70 kts. However, the use of maximum reverse is allowed down to aircraft stop in case of emergency.
If airport regulations restrict the use of reverse, select and maintain reverse idle until taxi speed is reached.
Stow the reversers before leaving the runway to avoid foreign object ingestion. (FCTM 02.160 P7)
ELAC
Thrust reverser efficiency is proportional to the square of the speed. So, it is recommended to use reverse thrust at high speeds.
Pull to reverse IDLE at main landing gear touchdown (not before). When REV is indicated in green on ECAM, MAX reverse may be applied.
The maximum reverse thrust is obtained at N1 between 70% and 85% and is controlled by the FADEC. Below 70 kts, reversers efficiency decreases rapidly, and below 60 kts with maximum reverse selected, there is a risk of engine stall. Therefore, it is recommended to smoothly reduce the reverse thrust to idle at 70 kts. However, the use of maximum reverse is allowed down to aircraft stop in case of emergency.
If airport regulations restrict the use of reverse, select and maintain reverse idle until taxi speed is reached.
Stow the reversers before leaving the runway to avoid foreign object ingestion. (FCTM 02.160 P7)
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ELAC - thanks for a comprehensive post. You appear to have missed "NOD's" reply where he corrected my post, but I appreciate your pointing it out again. It does show the degredation of stopping distance with defective reversers on a poor surface. He deduced a 31.5% increase. I have used 'icy' figures as those are the only ones that I have been given here for the AB on degraded surfaces, whereas I have access to the 73 figures which have a whole range of penalties from good to icy.
Personally, looking at the 'history' of the new runway surface in CGH and other 'new' surfaces I believe it was indeed 'poor', as I think the day's previous landing of this hull and the ATR showed, and I remain firmly unconvinced that a 55m increase in LDR was appropriate. Although the term 'slippery' is, indeed as you say unquantified, in the MELs I am acquainted with it is sufficient to preclude landing with a u/s reverser.
Operations on slippery runways or runways contaminated by snow, slush or standing water are PROHIBITED.
Personally, looking at the 'history' of the new runway surface in CGH and other 'new' surfaces I believe it was indeed 'poor', as I think the day's previous landing of this hull and the ATR showed, and I remain firmly unconvinced that a 55m increase in LDR was appropriate. Although the term 'slippery' is, indeed as you say unquantified, in the MELs I am acquainted with it is sufficient to preclude landing with a u/s reverser.
Operations on slippery runways or runways contaminated by snow, slush or standing water are PROHIBITED.
(737-700)
The addition for u/s reverser/s come from the 737 performance manual (not MEL) and as I stated the use of reverse WAS "considered in the original calculation of RLD for this aircraft". The point I was trying to make, rather than throw loads of % figures around, is that if there is poor or little braking action then reversers are all you have until you can get the wheels to grip - negligible or not.
The reverse handling techniques you quote are pretty much universal for wing-mounted engines
While you are there, what EPR would you expect to see using max reverse on a 320? 1.02?
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BOAC,
I appreciate your point but I think we are talking in circles here.
I did see NOD's reply when I was half way through with my own, but I didn't think he caught the essential distinction that in your post you took a value that applies to a condition (icy - .05) well below acceptable normal limits and applied it to the undefined subjective condition of "slippery", which it seems was deemed within normal limits by the operators using the runway that night. The comparison is invalid and so then is the use of the figure of 24% in any discussion regarding what the effect of reverse might be in this case. If slippery were in fact anything approaching a coefficient of .05 every airplane that landed would have gone off the end, not just this one.
In respect of the effect of reverse on landing distance I can't quote you exact figures for the A320, but figures for the A330 which are in a roughly similar range are as follows:
Runway Condition vs.
Effect of Reverse
Dry -1%
Wet -4%
1/4" Water -7%
1/2" Water -7%
1/4" Slush -7%
1/2" Slush -6%
Compacted Snow -6%
Ice -19%
As you can see, the effect of reverse on all contaminated surfaces other than ice is fairly much the same and is in a consistent range of 6%-7%. For the 320 the range is probably a bit higher, say 10%, but that would cover all contaminants with a friction coefficient of .20 or higher and very likely includes an allowance for hydroplaning.
As far as the actual runway condition being "poor" that's definitely open for investigation, but there was a very recent runway test and there will be several previous flights data to be examined. However, I don't think that the second previous landing's (the one at CGH) FDR data provides any indication of less than normal braking earlier in the day. The traces show a consistent 2.32 m/sec deceleration in response to 40º (about 50%) manual brake pedal application. Held all the way to 0 kts. that flight would have required about 1050m of ground roll to stop which I suspect would be within the normal distance for the force applied. As to the ATR landing the previous day, the number of factors differentiating that from this are too great to make meaningful correlation, but I'd wager my months pay packet that it takes more than braking action poor for an ATR to use 1800m+ on landing to stop.
Regarding operations with one reverse inoperative, this is not PROHIBITED in the Airbus MELs that I have seen. The MEL guidance says:
Followed by Operational Procedure guidance:
In practice an operator would require a specific takeoff performance calculation to be done if they proposed a takeoff as the standard allowances consider reverse to be operative, but there is no similar limitation in terms of considering a landing, which is what we are talking about here.
I do understand the point that you are trying to make regarding the use of reverse. The problem is that you are basing that point on procedures and figures that don't apply to this aircraft and relating it to conditions that it does not yet appear applied to this landing. From my perspective the use of reverse, particularly as it was on just the one engine, is likely to be entirely irrelevant to the outcome here, save for the investigation into the presumed confusion about how the PF handled the thrust levers.
ELAC
PS - Not having used these engines I don't have any info as to what the EPR would be for max. reverse, sorry.
I appreciate your point but I think we are talking in circles here.
I did see NOD's reply when I was half way through with my own, but I didn't think he caught the essential distinction that in your post you took a value that applies to a condition (icy - .05) well below acceptable normal limits and applied it to the undefined subjective condition of "slippery", which it seems was deemed within normal limits by the operators using the runway that night. The comparison is invalid and so then is the use of the figure of 24% in any discussion regarding what the effect of reverse might be in this case. If slippery were in fact anything approaching a coefficient of .05 every airplane that landed would have gone off the end, not just this one.
In respect of the effect of reverse on landing distance I can't quote you exact figures for the A320, but figures for the A330 which are in a roughly similar range are as follows:
Runway Condition vs.
Effect of Reverse
Dry -1%
Wet -4%
1/4" Water -7%
1/2" Water -7%
1/4" Slush -7%
1/2" Slush -6%
Compacted Snow -6%
Ice -19%
As you can see, the effect of reverse on all contaminated surfaces other than ice is fairly much the same and is in a consistent range of 6%-7%. For the 320 the range is probably a bit higher, say 10%, but that would cover all contaminants with a friction coefficient of .20 or higher and very likely includes an allowance for hydroplaning.
As far as the actual runway condition being "poor" that's definitely open for investigation, but there was a very recent runway test and there will be several previous flights data to be examined. However, I don't think that the second previous landing's (the one at CGH) FDR data provides any indication of less than normal braking earlier in the day. The traces show a consistent 2.32 m/sec deceleration in response to 40º (about 50%) manual brake pedal application. Held all the way to 0 kts. that flight would have required about 1050m of ground roll to stop which I suspect would be within the normal distance for the force applied. As to the ATR landing the previous day, the number of factors differentiating that from this are too great to make meaningful correlation, but I'd wager my months pay packet that it takes more than braking action poor for an ATR to use 1800m+ on landing to stop.
Regarding operations with one reverse inoperative, this is not PROHIBITED in the Airbus MELs that I have seen. The MEL guidance says:
"One or both may be inoperative ... Provided that no operation or procedure is predicated on their use"
Followed by Operational Procedure guidance:
"Refer to Operational Regulations for performance on wet, contaminated and slippery runway."
For the Airbus at least there is no prohibition, unless it is otherwise required by the regulator or the operator. This is probably a reflection of the fact that reverse wasn't used in calculating the basic performance in the first place. In practice an operator would require a specific takeoff performance calculation to be done if they proposed a takeoff as the standard allowances consider reverse to be operative, but there is no similar limitation in terms of considering a landing, which is what we are talking about here.
I do understand the point that you are trying to make regarding the use of reverse. The problem is that you are basing that point on procedures and figures that don't apply to this aircraft and relating it to conditions that it does not yet appear applied to this landing. From my perspective the use of reverse, particularly as it was on just the one engine, is likely to be entirely irrelevant to the outcome here, save for the investigation into the presumed confusion about how the PF handled the thrust levers.
ELAC
PS - Not having used these engines I don't have any info as to what the EPR would be for max. reverse, sorry.
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Agreed, we can stop 'circling'. A few points to clarify, though.
I have made it clear that my comments on reverse were general and not particularly accident specific.
The 'previous' landing of MBK I referred to was the previous day where it appeared to require 500' more LDA than there was (as 'reported' here).
The ATR 'excursion' was 'analysed' here on PPrune as aquaplaning at http://www.pprune.org/forums/showthread.php?t=284262.
. A few points to clarify, though.I have made it clear that my comments on reverse were general and not particularly accident specific.
The 'previous' landing of MBK I referred to was the previous day where it appeared to require 500' more LDA than there was (as 'reported' here).
The ATR 'excursion' was 'analysed' here on PPrune as aquaplaning at http://www.pprune.org/forums/showthread.php?t=284262.
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The crew that flew before (2nd previous landing) stated that they chose to use the previous MEL - one TL at reverse and one at idle - for safety reasons.
The captain said that doing so on that situation (short and slippery runway) was safer than bringing both TLs to reverse.
The captain said that doing so on that situation (short and slippery runway) was safer than bringing both TLs to reverse.
Last edited by Rob21; 21st Aug 2007 at 11:40. Reason: typo
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Silly thought
Is there a possibility, not likely, almost impossible to happen, that the pilots placed the left TL in reverse and the right on on Idle (or reverse) and... for some reason the right one went back to forward and stuck there?
Just a possibility, almost impossible?... Silly question?
Just a possibility, almost impossible?... Silly question?