American Airlines jet goes off runway in Jackson Hole, Wyoming
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Care to enlighten us on what SWA should have done at MDY?
IE: why stick your neck out if you don't have to?
Southwest did at Midway, and paid the price, no doubt about it.
I do suppose that there is a presumption on landing, that the brakes will work, that the spoilers will work and that the reversers will work (all as typical). But should anyone of them not work, that suffcient margin coupled with pilot skill can compensate.
It appears that two or more of these didn't fit the presumptions. I will await the findings to see which ones
It appears that two or more of these didn't fit the presumptions. I will await the findings to see which ones
Credit for reverse thrust
For normal landing performance, credit for reverse can be claimed (normally by the manufacturer) if reverse can be shown by certification to be sufficiently reliable. AFAIK very few manufacturers have achieved this, probably because of the many interlocks to ensure that reverse will not come out in flight, thus increasing the probability of system unavailability or relatively ‘inconsistent’ response on the ground (details in FAR/CS25.125 ‘… means other than wheel brakes').
For contaminated runway operations, the European approach is that reverse thrust can be used, but the increased risk is mitigated by the assumption of low exposure – rare occurrences, as it is strongly recommended that contaminated runways are avoided, and also that the landing performance is calculated by standard certification methods.
Some US operators appear to have a FAA dispensation similar to the EU approach, but I am uncertain as how the risks are mitigated, particularly as contaminated operations are often taken to be normal. Thus a reverse ‘failure’ on a contaminated runway contains an element of increased risk, which if encountered on a limiting runway (considered to be always for a contaminated runway), then an overrun is most likely, particularly as there little or no safety margin in the distance calculations, as there has to be with non-contaminated operations.
For contaminated runway operations, the European approach is that reverse thrust can be used, but the increased risk is mitigated by the assumption of low exposure – rare occurrences, as it is strongly recommended that contaminated runways are avoided, and also that the landing performance is calculated by standard certification methods.
Some US operators appear to have a FAA dispensation similar to the EU approach, but I am uncertain as how the risks are mitigated, particularly as contaminated operations are often taken to be normal. Thus a reverse ‘failure’ on a contaminated runway contains an element of increased risk, which if encountered on a limiting runway (considered to be always for a contaminated runway), then an overrun is most likely, particularly as there little or no safety margin in the distance calculations, as there has to be with non-contaminated operations.
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It appears the reversers were a long time in the "in-transit mode" when for all practical purposes they were stowed. So if you glance at the indicators at the right time the fact that they are amber might lead you to believe the reversers are behaving normally and will be available in a second or two. Obviously you don't wait forever but if your attention was drawn to the speedbrake problem at just the wrong moment would that delay the point at which your realise the reversers aren't working either. Cycle the reversers and are you at 12 seconds yet?
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FTR,
Here is a reanalysis of the gnd-speed and deceleration of the plane in question using a more advanced method for cases where few data points are available.
The deceleration data point at the 6000 ft runway mark is probably -1.8 m/s/s (the most problematic due to the limited view in the video).
Also included, the average decelerations, to 40 knots, for SWA1248 and 2 prior flights to SWA1248 at Chicago.
Here is a reanalysis of the gnd-speed and deceleration of the plane in question using a more advanced method for cases where few data points are available.
The deceleration data point at the 6000 ft runway mark is probably -1.8 m/s/s (the most problematic due to the limited view in the video).
Also included, the average decelerations, to 40 knots, for SWA1248 and 2 prior flights to SWA1248 at Chicago.
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Alph2Z, it seems to me your graph is off.
As the green line (speed) is a function of the red line (deceleration), it should become less steep after 5000' as deceleration becomes less.
The blue and purple dots at 0' for other aircraft are completely meaningless on a graph like this.
And the deceleration at 6000' shows -1.5 obviously, not -1.8 as you write. That would be at 5000'.
As the green line (speed) is a function of the red line (deceleration), it should become less steep after 5000' as deceleration becomes less.
The blue and purple dots at 0' for other aircraft are completely meaningless on a graph like this.
And the deceleration at 6000' shows -1.5 obviously, not -1.8 as you write. That would be at 5000'.
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Nic, see my replies after the alph2z >>
Alph2Z, it seems to me your graph is off. alph2z >> as I noted in my post, possibly the 6000 ft deceleration; the most difficult pt to determine from the video.
As the green line (speed) is a function of the red line (deceleration), it should become less steep after 5000' as deceleration becomes less. alph2z >> I quickly learned that it is extremely difficult to obtain acceleration from a plot of speed !
On the other hand numbers speak for themselves.
The blue and purple dots at 0' for other aircraft are completely meaningless on a graph like this. alph2z >> Nope, they tell us what average deceleration is achievable in fair to poor braking conditions.
And the deceleration at 6000' shows -1.5 obviously, not -1.8 as you write. That would be at 5000'. alph2z >> As I find typing-text to be extremely boring I kept it, maybe, too sparse. The numbers say -1.5 but if you believe braking action increased monotonically then I would suspect -1.8 is more probable
.
Alph2Z, it seems to me your graph is off. alph2z >> as I noted in my post, possibly the 6000 ft deceleration; the most difficult pt to determine from the video.
As the green line (speed) is a function of the red line (deceleration), it should become less steep after 5000' as deceleration becomes less. alph2z >> I quickly learned that it is extremely difficult to obtain acceleration from a plot of speed !
On the other hand numbers speak for themselves.The blue and purple dots at 0' for other aircraft are completely meaningless on a graph like this. alph2z >> Nope, they tell us what average deceleration is achievable in fair to poor braking conditions.
And the deceleration at 6000' shows -1.5 obviously, not -1.8 as you write. That would be at 5000'. alph2z >> As I find typing-text to be extremely boring I kept it, maybe, too sparse. The numbers say -1.5 but if you believe braking action increased monotonically then I would suspect -1.8 is more probable
.
Last edited by alph2z; 28th Jan 2011 at 18:23.
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The NTSB has released to the public, on Oct. 21 , 2011, a docket, NTSB accident id no DCA11IA015, which can be found at:
Accident ID DCA11IA015 Mode Aviation occurred on December 29, 2010 in Jackson Hole, WY United States Last Modified on October 14, 2011 16:10 Public Released on October 21, 2011 09:10 Total 33 document items
on this accident including a CVR transcript, an "Interview Summary" and a "Group Chairman's Factual Report" which includes the following:
Accident ID DCA11IA015 Mode Aviation occurred on December 29, 2010 in Jackson Hole, WY United States Last Modified on October 14, 2011 16:10 Public Released on October 21, 2011 09:10 Total 33 document items
on this accident including a CVR transcript, an "Interview Summary" and a "Group Chairman's Factual Report" which includes the following:
The FO said he planned to touchdown at 1,000 feet or less from the approach end of the runway, that he saw the runway about 300 to 400 feet above the ground, and that it looked like it was contaminated with snow. Once he transitioned to visual conditions he attempted to use the 1,000 foot marker as an aim point, and he believed he touched down firmly at about 800 feet past the threshold. He said when he tried to go into reverse, the levers moved slightly but he could not get the thrust reversers (TRs) out. On his second attempt to deploy the reversers, he told the captain that he could not get them into reverse. He said the captain took control of the TRs and told the FO to steer. The FO said he did not feel deceleration from the auto braking. He heard the captain say something about braking and he hit the brake pedals and went to max manual braking, but "the airplane felt like a sled." The captain confirmed that the flight landed as planned on "the first part of the runway," and that he told the first officer to recycle the thrust levers after they failed to deploy. The captain said he took control of the reversers and recycled the thrust levers 2 to 3 times and that both of them went to maximum manual braking but did not feel deceleration.
The FO said the TRs finally came out at about 2,000 feet or less remaining of the runway, and he could hear them operating but the deceleration was not normal. He saw the runway lights at the end and chose to go to the right because it looked smoother and he wanted to avoid hitting the lighting. He said there was about 3 feet of snow at the end of the runway where it had been plowed, and they impacted the snow, which stopped the airplane
Both pilots said the speed brake lever was armed during the flight, and it was still in the armed position after the aircraft stopped. Max autobrakes were set but were still in "max auto" after stopping. The captain said he did not check the "autobrakes" light during or after landing, and he did not look at the EICAS (engine indicating and crew alerting system) because he was looking out at the runway. The captain said he did not call out that the speedbrake was not deployed during landing, although the callout was part of the procedure. Both pilots confirmed that AAL policy was that speedbrakes should be deployed manually if they do not deploy automatically. The FO said that he noted the "left reverse isolation valve" and "auto spoiler"6 messages were on the EICAS after the incident.
The FO said the TRs finally came out at about 2,000 feet or less remaining of the runway, and he could hear them operating but the deceleration was not normal. He saw the runway lights at the end and chose to go to the right because it looked smoother and he wanted to avoid hitting the lighting. He said there was about 3 feet of snow at the end of the runway where it had been plowed, and they impacted the snow, which stopped the airplane
Both pilots said the speed brake lever was armed during the flight, and it was still in the armed position after the aircraft stopped. Max autobrakes were set but were still in "max auto" after stopping. The captain said he did not check the "autobrakes" light during or after landing, and he did not look at the EICAS (engine indicating and crew alerting system) because he was looking out at the runway. The captain said he did not call out that the speedbrake was not deployed during landing, although the callout was part of the procedure. Both pilots confirmed that AAL policy was that speedbrakes should be deployed manually if they do not deploy automatically. The FO said that he noted the "left reverse isolation valve" and "auto spoiler"6 messages were on the EICAS after the incident.
Could be both:
mechanical jam (as crew describes) preventing the throttle levers from moving into reverse detent (which is apparently required for automatic braking/spoiler operation) -
- and focusing on the TR jam distracted the crew (as they themselves note) from noticing that the spoilers were not up and the autobrakes did not go into operation, so they lost seconds before going to manual braking, and didn't note the spoiler condition at all.
Seems to boil down to the (still open, IMHO, from previous discussion) question of whether the plane could have been stopped had the crew immediately gone to manual braking and spoiler deployment (without TR) - on this slippery runway.
mechanical jam (as crew describes) preventing the throttle levers from moving into reverse detent (which is apparently required for automatic braking/spoiler operation) -
- and focusing on the TR jam distracted the crew (as they themselves note) from noticing that the spoilers were not up and the autobrakes did not go into operation, so they lost seconds before going to manual braking, and didn't note the spoiler condition at all.
Seems to boil down to the (still open, IMHO, from previous discussion) question of whether the plane could have been stopped had the crew immediately gone to manual braking and spoiler deployment (without TR) - on this slippery runway.
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I do not know the casue of this accident but your assumption is wrong.
"mechanical jam (as crew describes) preventing the throttle levers from moving into reverse detent (which is apparently required for automatic braking/spoiler operation)"
Autobrakes and auto spoilers are in no way dependent on reversers operating although deployment of the reversers will trigger spoiler deployment whether they are armed or not.
"mechanical jam (as crew describes) preventing the throttle levers from moving into reverse detent (which is apparently required for automatic braking/spoiler operation)"
Autobrakes and auto spoilers are in no way dependent on reversers operating although deployment of the reversers will trigger spoiler deployment whether they are armed or not.
errr.....
I do not know the cause of this accident but your assumption is wrong.
"mechanical jam (as crew describes) preventing the throttle levers from moving into reverse detent (which is apparently required for automatic braking/spoiler operation)"
Autobrakes and auto spoilers are in no way dependent on reversers operating although deployment of the reversers will trigger spoiler deployment whether they are armed or not.
"mechanical jam (as crew describes) preventing the throttle levers from moving into reverse detent (which is apparently required for automatic braking/spoiler operation)"
Autobrakes and auto spoilers are in no way dependent on reversers operating although deployment of the reversers will trigger spoiler deployment whether they are armed or not.
Does this occur? occasionally, even on an A340 having a hard landing event
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As a new captain I landed at Reno as the first flight at 0530 and found coming out of reverse I had no braking action at all so used full reverse to stop. Otherwise I would have gone off the end of the runway. The pilots always get blamed but sometimes it is the luck of the draw. Our reversers got us stopped, the brakes didn't. Thank God the reversers worked to stop us. If one had failed we would have been in the news.
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Thanks for the reply but I'm not sure if you are generalizing here or speaking directly to the B757-200? No question about it there are always exceptions to the rules or logic in this case. Is that what happened though?
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Nother skid
Jet's skid off runway highlights pilot complacency on automation
June 6, 2012 - 1:20PM
.
Brake system failures combined with human error led to an American Airlines jetliner skidding off a runway in Wyoming, the US National Transportation Safety Board said.
The flight from Chicago's O'Hare International Airport to Jackson Hole Airport on December 29, 2010, overshot the end of the 1.9km runway into a snowy field after landing. None of the 179 passengers and 6 crew members aboard the Boeing 757 were injured.
The incident highlights an issue that has arisen in recent accidents around the world: today's automated, reliable aircraft can breed complacency in pilots, the NTSB concluded.
A simultaneous series of events aboard the jetliner prevented its braking systems from functioning, the investigation found. The pilots, distracted by the initial failures, could have stopped the plane had they manually deployed some of those systems, the agency concluded.
"This incident demonstrates that experienced pilots can become distracted during unusual events," Katherine Wilson, an NTSB investigator who specializes in human performance, said.
The pilots attempted to switch on thrust reversers, devices that use engines to help a plane stop, after touchdown. The plane's computers prevented them from working, the investigation found. Pilots interviewed after the accident didn't know about the issue, the investigation found.
Panels on top of the wings known as speedbrakes, which flip up upon touchdown, also didn't work, the safety board found. Brakes are ineffective without those panels, which force a plane's wheels to the ground.
The captain on the flight erroneously called out that the speedbrakes were working, according to the NTSB. The plane could have stopped safely if the pilots had manually switched on the speedbrakes, the investigation found.
As jets have become more computer-driven, pilots spend more time monitoring autopilots and other systems, NTSB Chairman Debbie Hersman said in an interview after the hearing.
"That monitoring is no less important than the hand flying they once did, and failing to be attentive to the monitoring can be just as catastrophic," Hersman said.
The pilots landing in Jackson Hole, distracted by the thrust-reverser failure, didn't follow American's direction to check whether things such as speedbrakes are working, the NTSB concluded.
The NTSB voted to recommend that all airlines develop new training on the importance of monitoring speedbrakes. A review of incident reports by the safety board found 11 cases in which the speedbrakes activated and then deactivated on their own.
The board also recommended that a warning horn be installed on jets to alert pilots if the speedbrakes are not working. The board doesn't have authority to implement changes on its own.
Bloomberg/SMH
June 6, 2012 - 1:20PM
.
Brake system failures combined with human error led to an American Airlines jetliner skidding off a runway in Wyoming, the US National Transportation Safety Board said.
The flight from Chicago's O'Hare International Airport to Jackson Hole Airport on December 29, 2010, overshot the end of the 1.9km runway into a snowy field after landing. None of the 179 passengers and 6 crew members aboard the Boeing 757 were injured.
The incident highlights an issue that has arisen in recent accidents around the world: today's automated, reliable aircraft can breed complacency in pilots, the NTSB concluded.
A simultaneous series of events aboard the jetliner prevented its braking systems from functioning, the investigation found. The pilots, distracted by the initial failures, could have stopped the plane had they manually deployed some of those systems, the agency concluded.
"This incident demonstrates that experienced pilots can become distracted during unusual events," Katherine Wilson, an NTSB investigator who specializes in human performance, said.
The pilots attempted to switch on thrust reversers, devices that use engines to help a plane stop, after touchdown. The plane's computers prevented them from working, the investigation found. Pilots interviewed after the accident didn't know about the issue, the investigation found.
Panels on top of the wings known as speedbrakes, which flip up upon touchdown, also didn't work, the safety board found. Brakes are ineffective without those panels, which force a plane's wheels to the ground.
The captain on the flight erroneously called out that the speedbrakes were working, according to the NTSB. The plane could have stopped safely if the pilots had manually switched on the speedbrakes, the investigation found.
As jets have become more computer-driven, pilots spend more time monitoring autopilots and other systems, NTSB Chairman Debbie Hersman said in an interview after the hearing.
"That monitoring is no less important than the hand flying they once did, and failing to be attentive to the monitoring can be just as catastrophic," Hersman said.
The pilots landing in Jackson Hole, distracted by the thrust-reverser failure, didn't follow American's direction to check whether things such as speedbrakes are working, the NTSB concluded.
The NTSB voted to recommend that all airlines develop new training on the importance of monitoring speedbrakes. A review of incident reports by the safety board found 11 cases in which the speedbrakes activated and then deactivated on their own.
The board also recommended that a warning horn be installed on jets to alert pilots if the speedbrakes are not working. The board doesn't have authority to implement changes on its own.
Bloomberg/SMH
Last edited by Rollingthunder; 6th Jun 2012 at 11:13.
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Is the failure of speed brakes and thrust reversers (independent of associated failures such as hydraulics) part of the sim ride for anyone around here? Because it's not for me - every time I've landed a simulator in training without those devices, it was predictable, it was briefed, and it was all pretty much part of the usual checkride script. I would hope a few lesson plans will be getting an amendment after this.
It seems the body of the NTSB report does a commendable job of pointing out the technical gremlins at play, but the headline of Rollingthunder's quoted story is a predictable example of how the findings will be interpreted by the peanut gallery.
It seems the body of the NTSB report does a commendable job of pointing out the technical gremlins at play, but the headline of Rollingthunder's quoted story is a predictable example of how the findings will be interpreted by the peanut gallery.
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8. The captain's erroneous speedbrakes "deployed" callout was likely made in anticipation (not in confirmation) of speedbrake deployment after he observed the speedbrake handle's initial movement; after the "deployed" callout was made, both pilots likely presumed that the reliable automatic speedbrakes were functioning normally and focused on the thrust reverser problem.
One of those things where habit takes over. Incidentally, I've seen this exact situation before. FO is PF, auto spoilers inop, and Captain calls out "deployed" after touchdown.
I've observed AA crews. Their SOP seems for the PM to keep his hand at the base of the thrust levers (just above the fuel control switches) during landing. I still can't figure why they do that. I wonder if it would be better for the CA to have his hand near the spoiler lever during landing while he is PM instead. That way, there's a tactile confirmation that the lever has moved. What do you guys think?
One of those things where habit takes over. Incidentally, I've seen this exact situation before. FO is PF, auto spoilers inop, and Captain calls out "deployed" after touchdown.
I've observed AA crews. Their SOP seems for the PM to keep his hand at the base of the thrust levers (just above the fuel control switches) during landing. I still can't figure why they do that. I wonder if it would be better for the CA to have his hand near the spoiler lever during landing while he is PM instead. That way, there's a tactile confirmation that the lever has moved. What do you guys think?