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Originally Posted by ManaAdaSystem
(Post 10331045)
We have 15 knots tailwind limit on our NGs. Sometimes I need to use it. |
I think it’s an option. You pay, you get. SWA has a 10 knots tailwind limit? |
Re #35. This event should, must have a public investigation (‘An incident involving circumstances indicating that an accident nearly occurred’ - Annex 13). Overruns are a top order issue in safety statistics, thus the industry needs all possible feedback to help reduce the number of occurrences. The aircraft should have been capable of stopping well within the available landing distance; why didn’t it. More so, why did it enter the overrun area, either ‘engineered’ or as recommended by ICAO, this event has used more than all of the available distance. A ‘safe’ outcome does not indicate the quality of the decision to land; what were the factors influencing perceptions and decisions (PIREP), the operational safeguards, the assumptions, knowledge base. If there were technical failures then discuss them openly; over-dependence on reverse thrust, autobrake. If the conditions were not as ‘broadcast’, measured, assessed, then again we need to know why, particularly after the recommendations and changes from TALPA. What performance basis does this operator use; manufacturer’s OLD / FOLD, or some third party, is the data digitised, what are the opportunities for miscalculations, … … |
Now it can be done It would be smart to record each plane's landing weight and stopping distance and windspeed and runway at every landing. Experience would accrue faster and machine learning might save some damage :)
I wouldn't trust numbers under extreme conditions, but then I trained as an engineer, not a pilot. Edmund |
edmundronald;
Some FDM/FOQA programs provide this information already. The flight data requires GPS data in addition to the usual parameters used to calculate air distance from the threshold to the touchdown point. Determining touchdown point is easy with wheel-spin combined with a couple of other parameters but without wheel spin it can be done using a combination of vertical 'g', longitudinal 'g', spoiler deployment, radio-altitude. Using standard formula and an airport database, distance remaining as well as distance required at a certain deceleration rate can all be calculated for every landing and fed back in terms of the usual graphs. The data can be presented on-board but such systems require robust testing & certification if the runway remaining is to be helpful in real-time. Oviously runway contamination plays a significant role... |
Might be time for SW to install tail hooks on their aircraft and arresting gear at some of those shorter runways they’re making a habit of overrunning They don’t seem to be learning, the culture of hurrying through everything is a real problem, it’s endemic to their entire operation |
interesting comment from Southwest . Spinning the news of fact ? in a photo taken from a drone above the aircraft could leave to believe this .
Southwest Airlines Flight 278 from Oakland to Burbank landed safely and rolled to a stop at the end of a runway. The aircraft rolled into the overrun area known as the Engineered Material Arresting System (EMAS). |
“Rolled to a stop !” Considering that the aircraft stopped half way between the end of the runway and the airport wall / road, that is a lot of energy which has been absorbed. Not a ‘slow speed’ excursion then. In addition to ‘Lawyers can be found in the grass at the end of the runway’ add ‘The sound of EMAS crunching is like lawyers’ cash registers at full speed.’ |
Does SW use FOQA? |
edmundronald, PJ, Modern technology and analytical methods are very good at evaluating the past; ‘what happened’, but not so good as explaining ‘why’, or what might be done to reduce the likelihood of further occurrence. A widespread statistical evaluation might identify local hazards - deteriorating runway surface, poor drainage, on specific runways. However, if the analysis shows a widespread reduction is safety margin (challenges to the regulatory assumptions - ‘work as done is not the same as work as imagined’), then how will the industry react. Predictive calculation and guidance can help before landing, but this would still be limited by the quality of incoming information - runway braking action, extent of contamination. Reactive warnings when the aircraft is on the runway should have more accurate data, but if the landing has been well planned, then at best any ‘on the runway actions’ might only suggest the optimum way of using the remaining safety margins, which may already be insufficient. Many problems have been addressed with revised landing distance calculations (OLD /FOLD) - providing they are used. Additional hazards (lower safety margins) on wet runways have already been identified, but defences remain within the frailties of human evaluation; ground measurements, reporting, choice of performance and levels of braking / reverse. Heeding ‘Amalberti’s’ views on highly a reliable industry, we must be careful not to disturb the delicate balance which contributes to modern safety. Beware calls for more EMAS or other technologies, because ‘it saved the day’. Such systems are indicators of upstream problems; these must first be understood and fixed before resorting to ‘engineered’ solutions. What if EMAS gives crews a subconscious feeling of safety, we ‘drift’ to operate closer to existing (scant) margins of safety; which might become the norm. |
Originally Posted by alf5071h
(Post 10331748)
edmundronald, PJ, Beware calls for more EMAS or other technologies, because ‘it saved the day’. Such systems are indicators of upstream problems; these must first be understood and fixed before resorting to ‘engineered’ solutions. What if EMAS gives crews a subconscious feeling of safety, we ‘drift’ to operate closer to existing (scant) margins of safety; which might become the norm. |
The various formulae for landing distance provide margins, but real world surface conditions and variations in touchdown point, weight and speed (seemingly minor approaching the threshold) can blow past those margins.
Instituting larger margins can require lower weights and reduce revenue. An FOQA program would do well to monitor performance on shorter runways and raise flags when too much margin is getting used. A really clever FMS could take in groundspeed, weight and expected touchdown point against runway remaining and possibly recommend go around, but at what point in the approach? Better an EMAS excursion than a failed go around. |
Originally Posted by aterpster
(Post 10331775)
Like drivers over-relying on automobile anti-lock brakes? I don't believe a professional pilot would consider EMAS as a "buffer."
Is 737 takeoff and landing performance figured differently from that of the larger Boeing twins? I somehow got that impression from an earlier discussion of the 2005 Southwest MDW overrun.
Originally Posted by RatherBeFlying
(Post 10331846)
The various formulae for landing distance provide margins, but real world surface conditions and variations in touchdown point, weight and speed (seemingly minor approaching the threshold) can blow past those margins.
Originally Posted by RatherBeFlying
(Post 10331846)
Instituting larger margins can require lower weights and reduce revenue. An FOQA program would do well to monitor performance on shorter runways and raise flags when too much margin is getting used. The FOQA program looking over our shoulders supposedly does see things like long landings. If I'm not stable on approach or won't put it on in the touchdown zone even if there are miles of runway left, I can expect a call if I land or no call if I go around (and do it right ;)). Back in the 'good old days' it was considered manly to salvage a botched approach and a lot of metal was bent as a result. I cringe when I think of some of the 'watch this' stunts I saw with paying passengers decades ago on the 727. :eek: |
Originally Posted by edmundronald
(Post 10331405)
Now it can be done It would be smart to record each plane's landing weight and stopping distance and windspeed and runway at every landing. Experience would accrue faster and machine learning might save some damage :)
I wouldn't trust numbers under extreme conditions, but then I trained as an engineer, not a pilot. Edmund |
. Beware calls for more EMAS or other technologies, because ‘it saved the day’. Such systems are indicators of upstream problems; these must first be understood and fixed before resorting to ‘engineered’ solutions. No professional pilot would ever see EMAS as a reason to cut things tighter than is safe - but on the day that someone reports the braking action as "good" when it isn't, I'll be glad that it's there. ther |
Well said Ferret.
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aterpster #52 ‘I don’t believe’, but we cannot judge other pilots’ beliefs; this is just another example of the difference between how work should be done - imagined vs work as done - reality, even when we are in the same environment. Fursty Ferret #56. - (West Coast). Not mad, only an irrational human. The outcome of an event is not a measure of the hazards which existed before the landing, nor the quality of the decision. The pilots perception and judgement may have been exemplary, yet the outcome was not as expected; the margin of ‘unexpectedness’ should have been contained within current safety margins, but it wasn’t. Why? EMAS is a ‘fix’ for a runway with insufficient overrun margin, either being less than the ICAO recommendation, or for a specific hazard. It must not be consciously considered as part of the normal operational margins, but subconsciously … who knows. ‘No professional pilot would ever see…’ as above you assume that you know how all pilots will behave in all situations; the decision may not be the conscious ‘seeing’ it, but the subconscious bias from the knowledge that something else exists. Our biased belief is that we are rational, all pilots are rational, irrespective of situation and context; except that most accidents show that these beliefs are misformed. And re PIREPs, the conditions perceived by the report could have been ‘good’, by their judgement at that time, etc, etc; we don’t know, but having been broadcast, the potential for bias exists, we skip our revised assessment. With such subjectivity PIREPS are valueless for assessing actual conditions, good or not so (NB use in triggering downgrading assessment TALPA). |
Originally Posted by Airbubba
(Post 10331871)
. . . I cringe when I think of some of the 'watch this' stunts I saw with paying passengers decades ago on the 727. :eek:
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Originally Posted by alf5071h
(Post 10332071)
aterpster #52 ‘I don’t believe’, but we cannot judge other pilots’ beliefs; this is just another example of the difference between how work should be done - imagined vs work as done - reality, even when we are in the same environment. Fursty Ferret #56. - (West Coast). Not mad, only an irrational human. The outcome of an event is not a measure of the hazards which existed before the landing, nor the quality of the decision. The pilots perception and judgement may have been exemplary, yet the outcome was not as expected; the margin of ‘unexpectedness’ should have been contained within current safety margins, but it wasn’t. Why? EMAS is a ‘fix’ for a runway with insufficient overrun margin, either being less than the ICAO recommendation, or for a specific hazard. It must not be consciously considered as part of the normal operational margins, but subconsciously … who knows. ‘No professional pilot would ever see…’ as above you assume that you know how all pilots will behave in all situations; the decision may not be the conscious ‘seeing’ it, but the subconscious bias from the knowledge that something else exists. Our biased belief is that we are rational, all pilots are rational, irrespective of situation and context; except that most accidents show that these beliefs are misformed. And re PIREPs, the conditions perceived by the report could have been ‘good’, by their judgement at that time, etc, etc; we don’t know, but having been broadcast, the potential for bias exists, we skip our revised assessment. With such subjectivity PIREPS are valueless for assessing actual conditions, good or not so (NB use in triggering downgrading assessment TALPA). |
When the runway required as calculated under reported conditions approaches the runway available, it just doesn't take much variance in actual conditions to get this sort of outcome. As well, any variance in technique or execution from the assumptions inherent in the performance calculations invalidates the predicted performance to some degree.
With the above in mind, heavy rain associated with a cold front is often accompanied by changing wind direction and velocity during approach. Some amount of shearing in both horizontal and vertical planes is to be expected. This often makes staying on speed and profile during approach somewhat more challenging. The FDR data will shed some light on how much a factor that may have been. I'm just saying that arriving at the TDZ on speed and profile is more challenging in that sort of weather. I'm also curious as to the location on the airport where the reported wind measurement was taken. They have sensors all over the airport for the purpose of LLWS alerting. While there is no mention of any wind shear advisory having been issued, that does not necessarily mean that the wind at the end of rwy 08 was the same as the wind stated in the report. It's been many years now since I was based at BUR, but I certainly recall that the winds were always more variable and gusty when out of the West through North. "Normal" winds always seemed to 180/10! KBUR's location with respect to the nearby hills in all quadrants probably has allot to do with the "swirl effect" that so commonly rears it's ugly head when the wind kicks up. In the three years I flew out of BUR, I only landed during rain storms a couple of times.The rain was only moderate. And that was in a jet that required only about 3/4 of runway distance that a modern 737 at typical loads does. Maybe we were just being overly conservative in some people's view, but we were encouraged by the management to use an 80% (or 125% when looked at the other way) standard and that was before the 15% safety factor was even "a thing". Every pilot has used more runway than they planned to. It's just that most of the time, you don't land if it looks like you're gonna need all of it. So maybe something went way different than planned? |
Speed into the EMAS probably <30 kts
Originally Posted by safetypee
(Post 10331615)
“Rolled to a stop !” Considering that the aircraft stopped half way between the end of the runway and the airport wall / road, that is a lot of energy which has been absorbed. Not a ‘slow speed’ excursion then. In addition to ‘Lawyers can be found in the grass at the end of the runway’ add ‘The sound of EMAS crunching is like lawyers’ cash registers at full speed.’ Peter Lemme has updated his blog, citing a number of FAA references on overrun prevention as well as design criteria for construction and certification of EMAS: https://www.satcom.guru/2018/12/stop...ance.html#more Near the bottom of the page: An approximate 110 foot excursion into the EMAS occurred. This suggest that the airplane was travelling less than about 30 kntos. |
Thanks for the link Zeffy ; it presents a credible analysis. There could be several quibbles in the details; based on the aircraft length the ‘estimated’ distance into EMAS is reasonable, as would be the speed. However the aircraft stopped ~> 50m beyond the threshold (thus faster at runway exit), and the attention getting safety point is that the wall is ~ 80m beyond the threshold - a distance margin equivalent of ‘third’ to ‘home base’ - so no sliding into ‘the wall’ ! The underlying point is that these types of incident should not occur, (the second EMAS at BUR) which indicates an accumulation of several contributing factors, perhaps something common to BUR. |
Actually this incident is at least the third EMAS save at BUR, A-Rod's G-II in 2006 is missing from some of the lists:
A-Rod on Board Jet That Overruns RunwayThe Associated PressSaturday, October 14, 2006; 5:36 AM BURBANK, Calif. -- A private jet, carrying Yankees third baseman Alex Rodriguez and six others, overran a runway at Bob Hope Airport on Friday and was brought to a halt by an arresting system. "I spoke to Alex. He's fine," agent Scott Boras said. None of the seven people aboard were injured, federal officials said.The Gulfstream G-II carried five passengers and two crew members, the National Transportation Safety Board said in a statement from Washington, D.C. It departed from Las Vegas earlier in the day.The twin-engine jet was stopped by the Engineered Materials Arresting System, a 200-foot-long stretch of pavement injected with air bubbles designed to collapse under the weight of an aircraft as large as a Boeing 737 jet traveling as fast as 50 knots, airport spokesman Victor Gill said."It came to a pretty quick stop," Gill said.Damage to the aircraft was minor, the NTSB said. A-Rod on Board Jet That Overruns Runway |
aterpster #60 ‘I would have either held or gone around.’ I have no problem with that view - as we sit in the sunshine and clear views of hindsight. The lessons to be learnt will in the difference between our beliefs based on outcome, and the in-situation crew’s beliefs before the approach, and would we have performed any better. |
Originally Posted by Airbubba
(Post 10332588)
"... was stopped by the Engineered Materials Arresting System, a 200-foot-long stretch of pavement injected with air bubbles designed to collapse under the weight of an aircraft as large as a Boeing 737 jet traveling as fast as 50 knots."
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"Rolled to a stop" and "crunched to a stop" is a question of semantics and P.R. - but:
- it means the aircraft still retained at least 20% of its touchdown (ground) speed when it ran out of runway. - "less that about 30 knots" equates to "less than about 35 mph" or "less than about 55 kph." Not exactly slow. The NTSB does report on EMAS overruns (cf. Mike Pence/737/LGA and the incident at Yeager/Charleston, WV), so I imagine we'll get good information on the critical possible little details that make the difference - extra speed for gusts, reverser lever jam, failed deployment of spoilers, reverted-rubber planing, etc. |
Originally Posted by pattern_is_full
(Post 10332606)
The NTSB does report on EMAS overruns (cf. Mike Pence/737/LGA and the incident at Yeager/Charleston, WV), so I imagine we'll get good information on the critical possible little details that make the difference - extra speed for gusts, reverser lever jam, failed deployment of spoilers, reverted-rubber planing, etc. |
Originally Posted by alf5071h
(Post 10332593)
aterpster #60 ‘I would have either held or gone around.’ I have no problem with that view - as we sit in the sunshine and clear views of hindsight. The lessons to be learnt will in the difference between our beliefs based on outcome, and the in-situation crew’s beliefs before the approach, and would we have performed any better. |
aterpster, just to round this point off; ’similar situations’ are never the same ;) Does FSF ALAR CAAG ring any bells ? |
On a short runway I'd be minded to accept either heavy rain or a tailwind on limits but not both. That's stacking the odds too much.
Heavy rain implies the possibility of (perhaps locally) contaminated runway - a downwind landing on that is imo a rather risky call. |
So if the performance data was OK, and you diverted where does that leave you ? What could make a difference is local knowledge - does this runway feel like it actually meets the performance normally or not from past experience ? |
Originally Posted by Meester proach
(Post 10333330)
So if the performance data was OK, and you diverted where does that leave you ?
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Originally Posted by Meester proach
(Post 10333330)
So if the performance data was OK, and you diverted where does that leave you ? I view the landing distance numbers as limits, not goals. |
Tailwind is, somewhat, predictable. At least you can run the calculations with some extra knots and see where it leaves you. Braking action is harder, you don't know what you gonna get until you try. Not sure about California runways but I remember California freeways being quite slippery after months of accumulated dirt followed by rain. If the undershoot is flat you can duck under to get extra distance. Not everyone's cup of tea, but if you're close to the margain..... |
Originally Posted by alf5071h
(Post 10333284)
aterpster, just to round this point off; ’similar situations’ are never the same ;) In any case, holding until a red cells moves off the airport is using the "least cost of being wrong" operating philosophy, especially when the tailwind component is at its limit on a short (for jet transports) runway. |
FMC PROG 2/4 shows the wind components - headwind, tailwind, crosswind. Good reference if you're at the limits and performance is tight.
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Originally Posted by misd-agin
(Post 10333431)
FMC PROG 2/4 shows the wind components - headwind, tailwind, crosswind. Good reference if you're at the limits and performance is tight.
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Originally Posted by 172_driver
(Post 10333382)
If the undershoot is flat you can duck under to get extra distance. Not everyone's cup of tea, but if you're close to the margain..... |
So if the performance data was OK, and you diverted where does that leave you ? |
Originally Posted by 73qanda
(Post 10333538)
At home or in a hotel having a beer and planning my next holiday. |
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