Southwest B737 Overrun @ Chcago MDW
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dear tanker:
I have seen other NTSB reports stating that the plane "bounced" on landing. Reported by the PILOTS.
if you have other data, please post.
Also 4927-750= 4177 feet remaining to stop. that is not alot. especially when thrust reverser deployment was delayed by 18 seconds to a point with only 1000' remaining.
And if thrust reverser deployment was delayed because thrust levers were not at IDLE STOPS, then the plane's engines were developing forward thrust at IDLE PLUS power.
j
I have seen other NTSB reports stating that the plane "bounced" on landing. Reported by the PILOTS.
if you have other data, please post.
Also 4927-750= 4177 feet remaining to stop. that is not alot. especially when thrust reverser deployment was delayed by 18 seconds to a point with only 1000' remaining.
And if thrust reverser deployment was delayed because thrust levers were not at IDLE STOPS, then the plane's engines were developing forward thrust at IDLE PLUS power.
j
A few years ago a DC-9 slid off of the end of the runway at Traverse City, Michigan.
From what I read about it, the airport either had no current braking action readings (Saab, Tapley, Bomonk etc) and gave the flightcrew information which was incorrect. Based on the information which was given, if it had been accurate, the plane would have had a much better chance of stopping before the end.
The flying pilot landed (following a non-precision approach) well within the required touchdown zone and on speed. The Captain was not faulted-the airport was!
Years before that, a crew had a Captain on board who had never flown the DC-9 as First Officer, and was new in the left seat: nice combination (and no automation
). The Grand Forks (N.D.) Airport was supposed to spray chemicals on the runway and then sand. But NO chemicals were sprayed-only some sand was thrown onto either thin ice or snow. The rudder lost effectiveness because of tail-mounted engines and the plane slid sidways into the grass, and some crosswind might have been involved.
Be aware that the airport information might be far from accurate.
In the era of not just airline, but government budget cuts, anything is possible.
Did the Southwest crew ask Midway Approach for an approach with a headwind component?
From what I read about it, the airport either had no current braking action readings (Saab, Tapley, Bomonk etc) and gave the flightcrew information which was incorrect. Based on the information which was given, if it had been accurate, the plane would have had a much better chance of stopping before the end.
The flying pilot landed (following a non-precision approach) well within the required touchdown zone and on speed. The Captain was not faulted-the airport was!
Years before that, a crew had a Captain on board who had never flown the DC-9 as First Officer, and was new in the left seat: nice combination (and no automation
). The Grand Forks (N.D.) Airport was supposed to spray chemicals on the runway and then sand. But NO chemicals were sprayed-only some sand was thrown onto either thin ice or snow. The rudder lost effectiveness because of tail-mounted engines and the plane slid sidways into the grass, and some crosswind might have been involved.Be aware that the airport information might be far from accurate.
In the era of not just airline, but government budget cuts, anything is possible.
Did the Southwest crew ask Midway Approach for an approach with a headwind component?
Woukd you consider it to be two things did not occur as planned. 1. delay in reverse thrust. 2. Landing 2000 feet down the runway?
punkalouver:
The delay in achieving reverse thrust was, in my estimation, the most critical factor that did not go according to plan. The NTSB update of Dec 15, 2005 stated that touchdown occurred with aproximately 4500' of runway remaining. While this is 2000' less than the total runway length, it is only 1300' less than the available landing distance due to to the 696' displaced threshold. This means that assuming that they touched down with 4500' remaining, they were about 1300' beyond the landing threshold. Considering the low ceiling and visibility conditions that were in effect at the time of the approach, it would have been prudent to stay on glideslope all the way to roundout. Even if the aircraft were flown on to the runway with no roundout at all, (That was no landing, that was an ARRIVAL!) it would impact with the runway abeam the G/S antenna. I think it's safe to say that the G/S intercepts the ground at a point somewhere beyond the landing threshold of 31C. Perhaps someone who has access to Jeppview from home could post the distance available beyond glideslope. This distance minus the NTSB's estimated 4500' remaining at touchdown would represent the distance beyond the glideslope at which the aircraft touched down. This may not necessarily be as excessivily long of a landing as it first appears. Rather, it is about what one would expect if the glideslope were followed to around 50', followed by partially arresting the decent to an acceptable rate prior to touchdown. Especially with an 8 kt tailwind component. Even though dispatch and the laptop tool aboard the aircraft agreed that this landing was within limits, it was just barely so and consequently, if anything went wrong....... Well, it seems it did, at least in the form of not getting T/R deployment until 18 secs after touchdown for whatever reason. Any distance beyond the G/S antenna that the touchdown occurred would also contribute. To what extent that is a factor, I do not know. The investigation continues.
Best regards,
Westhawk
aka Capt PPRuNe
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What I find quite disturbing is the following from the NTSB statement/recommendation (my emphasis):
Either of those two numbers would give me great cause for concern. To expect such a short distance of runway to be remaining under normal good weather conditions, never mind those being experienced and forecast at the time would leave me with a serious doubt about using that runway in anything except a no-option emergency.
No doubt there are other pilots on here who have a bit more faith in their own piloting skills and accuracy that will have a go at me for being so cautious but we do this job in the knowledge that we will be minimising the risks as much as possible. If there is a tailwind component we factor everything by 150%. The touchdown zone is not the runway threshold but much further down the runway. We have contingency and alternate fuel in case of problems. Shouldn't we also factor in the amount of runway that should be left after coming to a complete stop should be something similar to the amount we leave behind us on touchdown? By all means, we can use the total amount available but we should only ever plan to use the total amount of runway available in an emergency and we have no alternative runway available within the limits of fuel remaining.
...The OPC then calculated the stopping margin. Depending on whether WET-FAIR or WET-POOR conditions were input, the computer calculated remaining runway after stopping at either 560 feet or 30 feet.
No doubt there are other pilots on here who have a bit more faith in their own piloting skills and accuracy that will have a go at me for being so cautious but we do this job in the knowledge that we will be minimising the risks as much as possible. If there is a tailwind component we factor everything by 150%. The touchdown zone is not the runway threshold but much further down the runway. We have contingency and alternate fuel in case of problems. Shouldn't we also factor in the amount of runway that should be left after coming to a complete stop should be something similar to the amount we leave behind us on touchdown? By all means, we can use the total amount available but we should only ever plan to use the total amount of runway available in an emergency and we have no alternative runway available within the limits of fuel remaining.
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Spot on, Danny. I too was befuddled by the notion that anyone would try to land a perfectly good airplane under those circumstances. No doubt some of that is a function of culture (Southwest's emphasis on OTP), and some of it may end up being that they were influenced by the success of the preceding flights whose pilots got lucky and made it in.
As is typical in accident investigation reports, the investigators will no doubt look for ways to address the causal factors through changes to the regulations. It will be very interesting to see how the final report addresses the legalities involved in this case. I wonder if they will require similar "buffering" to be applied to actual landings on contaminated runways as many regulators do when flight planning is done.
As is typical in accident investigation reports, the investigators will no doubt look for ways to address the causal factors through changes to the regulations. It will be very interesting to see how the final report addresses the legalities involved in this case. I wonder if they will require similar "buffering" to be applied to actual landings on contaminated runways as many regulators do when flight planning is done.
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Early on in 2005, there were 2 747-200's that over ran runways due to snow contaminated runways. Both were short runways. Thats 3 in one year!
We all like to complete the trip as planned, but at some point, we must say,
" Ain't hapenin today"; or "We'll take another runway thank you" or " We'll be diverting, have a nice day"
Lets look at past history along with the runway data, then make your decision to land.
If it can happen to someone else, it can happen to you!
We all like to complete the trip as planned, but at some point, we must say,
" Ain't hapenin today"; or "We'll take another runway thank you" or " We'll be diverting, have a nice day"
Lets look at past history along with the runway data, then make your decision to land.
If it can happen to someone else, it can happen to you!
Originally Posted by punkalouver
Very interesting post. To quote...
"In this particular case, at least one thing did not occur as planned for and the outcome is now history. "
Woukd you consider it to be two things did not occur as planned. 1. delay in reverse thrust. 2. Landing 2000 feet down the runway?
"In this particular case, at least one thing did not occur as planned for and the outcome is now history. "
Woukd you consider it to be two things did not occur as planned. 1. delay in reverse thrust. 2. Landing 2000 feet down the runway?
sounds like a spot on touchdown zone landing to me, some could argue you should duck under but that isn't SOP and the landing numbers are based on landing in the touchdown zone which they did.
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Originally Posted by jondc9
dear tanker:
I have seen other NTSB reports stating that the plane "bounced" on landing. Reported by the PILOTS.
if you have other data, please post.
Also 4927-750= 4177 feet remaining to stop. that is not alot. especially when thrust reverser deployment was delayed by 18 seconds to a point with only 1000' remaining.
And if thrust reverser deployment was delayed because thrust levers were not at IDLE STOPS, then the plane's engines were developing forward thrust at IDLE PLUS power.
j
I have seen other NTSB reports stating that the plane "bounced" on landing. Reported by the PILOTS.
if you have other data, please post.
Also 4927-750= 4177 feet remaining to stop. that is not alot. especially when thrust reverser deployment was delayed by 18 seconds to a point with only 1000' remaining.
And if thrust reverser deployment was delayed because thrust levers were not at IDLE STOPS, then the plane's engines were developing forward thrust at IDLE PLUS power.
j
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some questions about runway 31 center and there answers:
4927' remain if you follow the ILS glideslope to touchdown. There is a very slight downslope to the runway further confounding the stopping of a jet.
NTSB says plane landed at 4500' remaining which would be 427' past glideslope touchdown.
I indicated that a commercial pilot (cert) would have to demonstrate landing within 200' of a pre selected spot (at least I had to demo that to get my ticket).
BUT the NTSB has also said that you needed some 5300' to stop.
One question, does the handy dandy laptop computer with reversers figured it make its calculation from the THRESHOLD of the runway or from GS touchdown? I would bet "threshold" is the answer.
As someone indicated, it would be prudent in reduced visibility, night, snow and everything else to be right on the GS. As another pilot indicated, a ''non-flare'' landing to PLUNK it on at the GS intercept point of the runway would be prudent too.
AND to the great debate about "ducking" the Glideslope. And whether it is SOP or not. THE Federal Regulations are quite specific in that a Turbine powered plane must remain at or above the Glideslope. BUT IT ALSO SAYS THAT YOU CAN GO BELOW THE GLIDESLOPE WHEN REQURIED TO MAKE A SAFE LANDING. Generally this is regarded as the MM or equivelent position on the approach.
I recall an old joke at Midway. A jet was being towed off the runway after a virtual over run (not as deadly as the incident in question). The copilot said to the captain, "what happened?". The captain's reply was, "he followed the glideslope".
I have landed many times in 737's and DC9's (and once in a piper arrow!@) at Midway airport. EACH landing is a unique adventure and the criticality of the landing and approach (and indeed any operation there) must be studied.
Sometimes I would "duck" the glideslope in accordance with regulations, other times I would not. BUT each time I did, I had briefed this with the other pilot and verbally declared, "departing glideslope visually".
In retrospect this plane should not have landed on this runway in this wx.
IF reverse is to be credited towards landing distance (and I don't think it should be) then there must be an emergency memory item for "reversers fail to deploy".
1> are you above 100knots? if so, retract spoilers and firewall throttles FORWARD thrust and takeoff again.
2> are you below 100 knots, verify throttles idle, spoilers extended max toe braking and re attempt reverser deployment...if reversers deploy firewall REVERSE thrust to complete stop even if this damages the engines.
regards
jon
4927' remain if you follow the ILS glideslope to touchdown. There is a very slight downslope to the runway further confounding the stopping of a jet.
NTSB says plane landed at 4500' remaining which would be 427' past glideslope touchdown.
I indicated that a commercial pilot (cert) would have to demonstrate landing within 200' of a pre selected spot (at least I had to demo that to get my ticket).
BUT the NTSB has also said that you needed some 5300' to stop.
One question, does the handy dandy laptop computer with reversers figured it make its calculation from the THRESHOLD of the runway or from GS touchdown? I would bet "threshold" is the answer.
As someone indicated, it would be prudent in reduced visibility, night, snow and everything else to be right on the GS. As another pilot indicated, a ''non-flare'' landing to PLUNK it on at the GS intercept point of the runway would be prudent too.
AND to the great debate about "ducking" the Glideslope. And whether it is SOP or not. THE Federal Regulations are quite specific in that a Turbine powered plane must remain at or above the Glideslope. BUT IT ALSO SAYS THAT YOU CAN GO BELOW THE GLIDESLOPE WHEN REQURIED TO MAKE A SAFE LANDING. Generally this is regarded as the MM or equivelent position on the approach.
I recall an old joke at Midway. A jet was being towed off the runway after a virtual over run (not as deadly as the incident in question). The copilot said to the captain, "what happened?". The captain's reply was, "he followed the glideslope".
I have landed many times in 737's and DC9's (and once in a piper arrow!@) at Midway airport. EACH landing is a unique adventure and the criticality of the landing and approach (and indeed any operation there) must be studied.
Sometimes I would "duck" the glideslope in accordance with regulations, other times I would not. BUT each time I did, I had briefed this with the other pilot and verbally declared, "departing glideslope visually".
In retrospect this plane should not have landed on this runway in this wx.
IF reverse is to be credited towards landing distance (and I don't think it should be) then there must be an emergency memory item for "reversers fail to deploy".
1> are you above 100knots? if so, retract spoilers and firewall throttles FORWARD thrust and takeoff again.
2> are you below 100 knots, verify throttles idle, spoilers extended max toe braking and re attempt reverser deployment...if reversers deploy firewall REVERSE thrust to complete stop even if this damages the engines.
regards
jon
My local CAA allows thrust reverse to be used for ALD calculations on wet/contaminated runways but still LDA has to be 67% longer than ALD at destination or 42% at alternate. 560 or 30 ft on 4927ft long runway doesn't sound like 67% margin to me but then I'm no expert on FARs. Perhaps FAA allows lesser margins. Anyone on the other side of the pond care to comment?
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Clandestio,
Can be overcome by dispatcing with a destination that is within the 1,67 planning margin when dry, but not when cont.
Now, due to the contamination, the runway is "below minima", and you dispatch with 2 alternates. Whopla, suddenly you're into "operational" requirements, not "planning" requirements.
Sad but true - and has happened!
Can be overcome by dispatcing with a destination that is within the 1,67 planning margin when dry, but not when cont.
Now, due to the contamination, the runway is "below minima", and you dispatch with 2 alternates. Whopla, suddenly you're into "operational" requirements, not "planning" requirements.
Sad but true - and has happened!
Still don't get it but perhaps that is because our local interpretation is that prescribed margins must exist at touchdown i.e. they are operational and not dispatch margins. There is a bit silly situation when destination rwy has between 42 and 67 percent margin so it can be used as alternate but not as destination. To rectify it, 67% will be abolished soon.
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Originally Posted by canyonblue737
they did not land 2000 feet down, they landed 1300 ft from the displaced threshold and 300 ft beyond the 1000 ft mark that the GS brings you to.
sounds like a spot on touchdown zone landing to me, some could argue you should duck under but that isn't SOP and the landing numbers are based on landing in the touchdown zone which they did.
sounds like a spot on touchdown zone landing to me, some could argue you should duck under but that isn't SOP and the landing numbers are based on landing in the touchdown zone which they did.
Are you sure? I'm not sure. Looking at online approach plates, I got the airport chart for MDW which shows that there is a displaced threshhold of 696 feet. The airport chart shows a threshhold crossing height(TCH) of the 3.00° glideslope of 51 feet. Is this TCH for the beginning of the runway or is it for the displaced threshhold. I don't know. The approach plate doesn't say.
However, the 6869' long runway 01 at Washington National(chosen because of similar length) with no displaced threshhold has it's 3.00° glideslope TCH at 51 feet as well. Is an assumption being made on where the GPI(ground point of interception) is for the glideslope at MDW. Is it being assumed that it is 1000 feet beyond the displaced threshhold. The government approach chart doesn't say. Perhaps the Jeppesen chart does. It may very well be approximately 300 feet beyond the displaced threshhold.
If the DCA GS brings you to a 1000' touchdown point, I am assuming so does the MDW 31C GS does as well. If that TCH at MDW is over the very beginning of the runway, it would leave 5522' remaining instead of the "about 4500" feet of runway that the NTSB says actually did remain at touchdown. It would be nice to have this clarified.
However my original statement of landing 2000 feet down the runway would appear to be incorrect from a displaced threshhold point of view. It came from this Flight International quote "The Southwest Airlines Boeing 737-700 that overran Chicago Midway airport’s runway 31C onto a road landed about 620m (2,000ft) along the 1,990m snow-contaminated runway with a tailwind".
Last edited by punkalouver; 29th Jan 2006 at 00:09.
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It might be good data to compile a list of which authorities permit the R/T stopping credit (under what circumstances, and when implemented), and which do not.
Inasmuch as reversers do not have the same degree of deployment redundancy as (e.g.) brakes, it seems a weak link in the system (as evidenced at KMDW)
Inasmuch as reversers do not have the same degree of deployment redundancy as (e.g.) brakes, it seems a weak link in the system (as evidenced at KMDW)
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Most of the time we operate out of 8,000+ runways so can be very conservative but if you always fly into Midway you have to rely on the charts to say yes or no.
My last seven years at AA I flew into Tegucigalpa, TGU, and a lot of times one degree or one knot of tailwind determined if the takeoff or landing was legal and if it was wet or dry. We couldn't put in an extra 500 feet for the kids. Why have charts approved by the FAA if you don't go by them. Either you are legal or you are not. Extreme circumstances like braking action poor to nil require judgement as to believing the charts but operating into marginal airports a standard method of operation is required. They were legal to land but I think the FAA will change the rules so thrust reverse won't be allowed to calculate landing distance like on all equipment I have ever flown.
My last seven years at AA I flew into Tegucigalpa, TGU, and a lot of times one degree or one knot of tailwind determined if the takeoff or landing was legal and if it was wet or dry. We couldn't put in an extra 500 feet for the kids. Why have charts approved by the FAA if you don't go by them. Either you are legal or you are not. Extreme circumstances like braking action poor to nil require judgement as to believing the charts but operating into marginal airports a standard method of operation is required. They were legal to land but I think the FAA will change the rules so thrust reverse won't be allowed to calculate landing distance like on all equipment I have ever flown.
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Originally Posted by jondc9
the NTSB has also said that you needed some 5300' to stop.
One question, does the handy dandy laptop computer with reversers figured it make its calculation from the THRESHOLD of the runway or from GS touchdown? I would bet "threshold" is the answer.
jon
One question, does the handy dandy laptop computer with reversers figured it make its calculation from the THRESHOLD of the runway or from GS touchdown? I would bet "threshold" is the answer.
jon
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Originally Posted by Tanker
The OPC makes it calculations from GS touchdown and not the threshold. You lose the bet.
I am happy to lose this bet. It seems that you have special insight into this OPC system.
I will assume that you are a 737-700 pilot for this question then:
given a report of Fair braking action first 2/3 of runway and poor braking action the last 1/3 of runway would YOU enter ''wet poor'' or ''wet fair'' into your OPC?
who knows, you might even fly for SW. I don't want you to get in any trouble for answering the question.
AND if you did enter wet-poor and saw you would have a 30' margin, would YOU have made the approach?
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Originally Posted by Tanker
The OPC makes it calculations from GS touchdown and not the threshold. You lose the bet.
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Good discussions, these. The thing that should be recognized is that there is a GPI and an RPI; Ground Point of Interception and Runway Point of Interception, and they are not necessarily the same. The GPI is where the glide slope intercepts the level plane of the runway threshold; and the RPI is where the glide slope intercepts the surface of the runway. If there is a slope on the runway, these points will differ, and they may differ quite a lot. It may seem like they shouldn’t be much different, but when you consider the shallow angle of the glide slope (3.00-degree, 2.88-degree, etc.) the difference can easily be in the hundreds of feet. And, as the glide slope shack is displaced off to the side of the runway, by varying distances, and the true glide slope (more of a parabola than a straight line) does not, or should not, intersect the runway (or even the plane of the threshold) the actual "glide slope intercept point" is always a good discussion issue.
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I actually think we have a good discussion going.
For the RECORD (please respond if incorrect)
CHICAGO MIDWAY runway 31Center usable length landing beyond GLIDESLOPE is:
4927feet.
landing beyond the displaced threshold of 31 Center is 5826 feet usable length.
899 feet between the displaced threshold and glideslope touchdown (theoretical touchdown if we want to be technical).
The runway itself is 6522 feet long ( like for takeoff man) 1595 feet that on an instrument approach could really not be used. (though read my discussion of ducking the gs above)
the NTSB says the plane landed with 4500 feet remaining. With my primative brain this means that the plane landed 427 feet beyond GS touchdown. 2022 feet of runway (concrete) that wasn't used due to legit reasons (displaced threshold.
I did make a comment that a commercial pilot has to demonstrate in his practical test landing within 200 feet of a spot. (of course this is done visually).
A casual glance would tell a novice pilot that the runway was 6522' long. But there are so many factors that really lead you to think you are lucky to have 4927' on a dark and stormy night with very low visability. would that 427 feet have been useful? I would say yes. Plane still might have gotten pranged up but not have gone onto roadway enough to hit car? But again, we still don't have all the facts.
I have a call into NTSB asking if spoilers deployed automatically. STILL no answer.
Remember folks this media (forum) does not do justice to any of our thoughts.
over
jon
For the RECORD (please respond if incorrect)
CHICAGO MIDWAY runway 31Center usable length landing beyond GLIDESLOPE is:
4927feet.
landing beyond the displaced threshold of 31 Center is 5826 feet usable length.
899 feet between the displaced threshold and glideslope touchdown (theoretical touchdown if we want to be technical).
The runway itself is 6522 feet long ( like for takeoff man) 1595 feet that on an instrument approach could really not be used. (though read my discussion of ducking the gs above)
the NTSB says the plane landed with 4500 feet remaining. With my primative brain this means that the plane landed 427 feet beyond GS touchdown. 2022 feet of runway (concrete) that wasn't used due to legit reasons (displaced threshold.
I did make a comment that a commercial pilot has to demonstrate in his practical test landing within 200 feet of a spot. (of course this is done visually).
A casual glance would tell a novice pilot that the runway was 6522' long. But there are so many factors that really lead you to think you are lucky to have 4927' on a dark and stormy night with very low visability. would that 427 feet have been useful? I would say yes. Plane still might have gotten pranged up but not have gone onto roadway enough to hit car? But again, we still don't have all the facts.
I have a call into NTSB asking if spoilers deployed automatically. STILL no answer.
Remember folks this media (forum) does not do justice to any of our thoughts.
over
jon