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Marshall

738 over runs

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From the various reports on PPrune, AVHERALD ETC, there are numerous reports of 738 over runs, excursions etc. What is wrong?    

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Bigger, heavier aircraft, higher approach speeds with the same size brakes as smaller lighter models.

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Can’t place bigger wheels/ rotors/brakes on the gear because it won’t fit on retraction.  Contrast this to the wheels on the 320 vs 321.  The 321’s wheels are substantially larger.

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We haven't seen anything further from the TSB on the YHZ14 overrun so we don't know what the circumstances were other than what the METARS provides, (I'm not a fan of using ADS-B/Flightradar24 data because the sample rates, data sources, data validity, etc., are not defined so don't have standards which would permit use in a serious investigation).

By recollection only, the overrun accidents which have final reports associated, appear to indicate that the touchdown point is beyond the normal TDZ of between 500ft & 3000ft/first-third-of-runway, (see FAA doc below). For example, the 2018 Sochi overrun accident report which has just been issued by the MAK. Two causal factors are listed in the Report as:

3. Conclusion

The aircraft overrun, destroying and damage by fire were caused by the following factors

    - repeated disregarding of the windshear warnings which when entered a horizontal windshear (changing from the head wind to tail one) at low altitude resulted in landing at distance of 1285m from the RWY threshold (overrunning the landing zone by 385m) with the increased IAS and tail wind;

    - landing to the runway, when its normative friction coefficient was less than 0.3 that according to the regulations in force, did not allow to land.

The full report is available at https://mak-iac.org/upload/iblock/f4b/report_vq-bji_en.pdf

In general, for airborne distances longer than 3000ft there have been several factors involved, not just one single cause. The most common one appears to be "float time" - flying just above the runway surface waiting for touchdown rather than "planting" the airplane under one's control. Long, dry runways can invite "finessing" the landing I suppose, holding the aircraft for a smooth landing instead of following the Boeing SOPs which requires a flare duration of 8" or less from the 50ft/threshold point to the touchdown point, but that builds operational habits including cognitive and "muscle-memory" habits that can get one into trouble when landing on a short, contaminated runway. Boeing's landing data tables for normal landings, (vice non-normal procedures), provide for a touchdown at 1500ft past the threshold.

Approach speeds for the 800 appear to be roughly the same as the Classic (400) B737, perhaps a few knots higher but not significantly so. Regardless of type, approach speeds are in the neighbourhood of 220fps to 250fps, sp the margins built into the certification data for published landing distances get swallowed up very quickly. It's been a while since I flew the A320 but i have the impression that the approach speeds are somewhat lower for that type. (I haven't flown the B737 at all, just the B727).

I don't sense that brake size has much to do with overruns. I think the causes lie in those decision-making, energy-management and SOP areas of an operation. Where needed, I think -800 brake performance in a rejected takeoff is impressive. 

Runway excursions, (off either side) are a different kettle of fish, involving loss-of-control during crosswinds, assymetric thrust, contaminated runways...

*https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_91-79A.pdf

 

 

Edited by Don Hudson
Add link to FAA Advisory Circular 91-79A
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Don,

Part of the 737-8 introduction at AC was a caution to pilots regarding the deceleration ability of the aircraft.  If was recommended to use Max full reverse until the pilot was accustomed to how the Max decelerates, as it is slower than most aircraft we are used too.

Obviously this is reflected in performance numbers and is not really a safety issue.  I’m just saying it doesn’t decelerate as fast as an A320 because of the smaller brakes.  The smaller brakes are a function of fit in the wheel well of an aircraft originally designed at far less weight and inertia. Hence the landing and accelerate stop distances have lengthened.  Hence less margin for error, incorrect contaminants/ rapidly changing conditions.

You don’t see many 737-800’s in Mexico City.  AC looked at sending it to MEX as well.  Doesn’t work.  It’s the same performance issues that steered AC away from the Max-9.  If you remember the original order was mostly Max-9’s.

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The 737 is at least one generation further along than is should be.  The systems are being stretch beyond their limits but a "just make it work" approach.

The aircraft is makeup on a pig but the mascara is starting to run.

It is outdated and needs to be replaced with a clean slate design.

 

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Thanks for the response, Turbofan. Good to know that this aspect of the -800 is being emphasized; it deserves to be. One question, -does AC require that the landing distance be calculated and recorded for all landings?

On brake / wheel size, understand the point being made regarding reduced margins compared with other types; - reduced brake energy absorption capability, smaller wheel footprint.

The question and the point being made is, given all things equal, the correctly-calculated performance data provides sufficient (but reduced?) margin for the landing when compared to other B737 types and the Airbus. Aside from sudden windshear conditions and hot runways, both of which can cause "float", the other variable in otherwise normal landings may be handling techniques of the flare and touchdown, (note: some Classics and the 800 & 900 are certified for a 15kt tailwind landing. If the numbers are critical, one wonders why this is so?)

To test the notion, I'm wondering if there is an -800 overrun event in which the airplane touchdown was within 3000ft of the threshold?

Interesting question from Marshall! I've been long-wondering why some airborne distances are still a few hundred feet over the 3000ft point. Most of the time, the touchdown point is within the pilots' control give or take ~400ft or about 2 seconds.

One other point is, any data analysis must be sampled often enough to examine certain parameters every one-eighth or even one-sixteenth of a second. Determining touchdown point is not at all straightforward as looking at the "air-ground" switch - not at 220ft to 250ft per second, anyway.

 

Edited by Don Hudson
in blue font

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11 hours ago, Don Hudson said:

Thanks for the response, Turbofan. Good to know that this aspect of the -800 is being emphasized; it deserves to be. One question, -does AC require that the landing distance be calculated and recorded for all landings?

 

 

The fleet types appear to be migrating that way.  A few aircraft are now getting Landing performance data via ACARS as part of the descent planning stage. The 737 is one of them.  It is quite advanced as they can input a FICON report and the ACARS spits out contaminated landing distance data. So far the NB 320 doesn’t so long as certain criteria is met.  That criteria is probably the same as prior to your retirement.

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My 2 cents.

I have flown all the different types at Air Canada.

The auto throttle on the 737 is rudimentary. When the autopilot is disconnected, the autothrottle must be disconnected, ( one can leave it on longer with changes to SOP lately.)

The other types of autothrottles or autothrust can remain on till rollout. Some people will laugh and say pilots should be able to fly their airplanes....

Airspeed control is critical, and I find that it can creep up . If one gets too slow, then one can add too much power and speed gets too fast as well.

To compensate for this higher speed, one has a tendency to raise nose slightly to bleed off the speed . In doing so, they eat up valuable runway, landing too long. Add a slight tailwind and contaminant, it is a huge problem. 
 

I like the technical comments and the talk of over use of automation etc., but it all happens in the last 50 feet on any aircraft where a pilot earns their money in my opinion.

 

 

 

 

 

 

Edited by xxx
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10 hours ago, Turbofan said:

The fleet types appear to be migrating that way.  A few aircraft are now getting Landing performance data via ACARS as part of the descent planning stage. The 737 is one of them.  It is quite advanced as they can input a FICON report and the ACARS spits out contaminated landing distance data. So far the NB 320 doesn’t so long as certain criteria is met.  That criteria is probably the same as prior to your retirement.

Re FICON & transmitted contaminated landing distance data, that's very cool.

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3 hours ago, xxx said:

My 2 cents.

I have flown all the different types at Air Canada.

The auto throttle on the 737 is rudimentary. When the autopilot is disconnected, the autothrottle must be disconnected, ( one can leave it on longer with changes to SOP lately.)

The other types of autothrottles or autothrust can remain on till rollout. Some people will laugh and say pilots should be able to fly their airplanes....

Airspeed control is critical, and I find that it can creep up . If one gets too slow, then one can add too much power and speed gets too fast as well.

To compensate for this higher speed, one has a tendency to raise nose slightly to bleed off the speed . In doing so, they eat up valuable runway, landing too long. Add a slight tailwind and contaminant, it is a huge problem. 

I like the technical comments and the talk of over use of automation etc., but it all happens in the last 50 feet on any aircraft where a pilot earns their money in my opinion.

Your "2c" very much appreciated, XXX because it provides some insight into the thinking that may contribute to longer airborne distances, particularly if one knows in the back of the mind that one has 10,000ft in front of one.

In general, the accuracy with which Vref+5 plus corrections is flown is much better on the Airbus than the B737, so I think your comments make good sense.

Re "...in the last 50 feet...", couldn't agree more. In fact, (as all are probably aware by now), actual "hands-on, manual flight" for a year's flying might amount to a couple of hours depending upon type.

 

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Thanks  Captain Hudson,

I quietly read and observe everything pilots like yourselves who have been around the block say and do.👍

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1 hour ago, Don Hudson said:

actual "hands-on, manual flight" for a year's flying might amount to a couple of hours depending upon type.

How sad..........

I'm old school, out in the pasture now, living in Dotville, but the most fun with ANY aircraft was always the "hands-on" departure and "hands-on" arrival when it came to  airline flying.. 

Naturally a different story when handling a "whiz-bang" aircraft....much more hands on which was really FUN.....😁

Don, your comment also enters into the discussion concerning the lack of complete and full knowledge with  respect to an increasing number of the pilots  today that do not understand some of the more simplistic areas of basic aerodynamics.. as an armchair quarterback I view  some examples like : AF in the Atlantic,( failure to recognize a stall),  even the MCAS incidents, becoming a water dart without even retarding the thrust levers when the speed was increasing so quickly.

Alas..................technology and AI move forward but us old guys did ok without all the bytes and bits.😂  No yelling today, just watching the clouds anchored on the horizon during this dreary  winter day, anticipating a 100 or so feet below the warm, clear and  blue waters of the Caribbean in a few days ...

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Hi Kip;

Well, two to five hours a year of manual handling is probably all you and I did when we weren't "dots"! 😉, eh? I handflew every airplane I was on up to 10, sometimes to cruise altitude, and often disconnected at top-of-descent and handflew the approach/landing. Later on I found that it got everybody's attention when the old guy in the left seat disconnected everything - they had to listen, set the altitude alert, the headings and speeds as well as program the FMS...(but not out of LHR and not into HKG).

Bits'n bytes...no matter what, it's about training, training, training, and more training.

Kip, re ". . . anticipating a 100 or so feet below the warm, clear and  blue waters of the Caribbean in a few days ... ", now THAT says it all !! Enjoy, and post a photo or two of that turquoise water!

👍

 

 

Edited by Don Hudson

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3 hours ago, Don Hudson said:

Hi Kip;

Well, two to five hours a year of manual handling is probably all you and I did when we weren't "dots"! 😉, eh? I handflew every airplane I was on up to 10, sometimes to cruise altitude, and often disconnected at top-of-descent and handflew the approach/landing. Later on I found that it got everybody's attention when the old guy in the left seat disconnected everything - they had to listen, set the altitude alert, the headings and speeds as well as program the FMS...(but not out of LHR and not into HKG).

Bits'n bytes...no matter what, it's about training, training, training, and more training.

Kip, re ". . . anticipating a 100 or so feet below the warm, clear and  blue waters of the Caribbean in a few days ... ", now THAT says it all !! Enjoy, and post a photo or two of that turquoise water!

👍

 

 

👍

My rule is that once a pairing everything comes off.   
 

Ehem.......the automation I mean.

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Good rule. I used to offer that to F/Os on their leg, sometimes with a nudge but no one took up the offer. Engaged the a/p at 400', click-click at 400' on the other end.

Thank you for clarifying "off"...

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52 minutes ago, Don Hudson said:

Good rule. I used to offer that to F/Os on their leg, sometimes with a nudge but no one took up the offer. Engaged the a/p at 400', click-click at 400' on the other end

Unbelievable. 😳Unfortunately I never had a chance to share the flight deck with you because if you had ...... after making that offer to me you would have to ORDER me to put the magic back on 🤨🤨

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Well, that's what I thought would happen, (yippee...), so it was a surprise and a bit disappointing. I think it was the thrust lever system; there was a lot of concern and discomfort disconnecting the autothrust and flying it, (A320, A330, A340) like a C172. It was all just a matter of knowing how it worked. There was also a lot of unspoken discouragement at hand-flying. The FCOM had a statement in it that the design of the autoflight system contemplated that it would be engaged immediately after takeoff and disengaged on the landing roll-out at destination, or something like that. It was challenged by good people who wanted FCOM statements permitting hand-flying and gradually it became "acceptable" with reminders of reconnecting the automagic in busy terminals, untoward weather and so on, which was fair enough. And of course one can't hand-fly above FL290.

There was nothing so satisfying as doing a visual in one of those machines and making it pretty, (but I haven't been upside down pulling 'g' in a fighter...;-)

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At WD on the A-310 we used to hand fly up to 10000 and down from 10000, at pilots discretion, but TC got in the picture and we were then told to use the magic from at least 1000 feet going up and on the way down, onto final approach. Unless it was a ProfCheck most of us older guys sorta bent that rule but it was very obvious that the younger generation were more comfortable using the magic as much as they could.
As a newbie I was in the right seat when the “young” Captain had to do a go around due to traffic on 24 L (then) and we were turned south and then a couple more turns east then for some reason to the SE and back to the E.  by this time the “picture” of the runway was no longer on the PFD. The young fellow asked me if I knew where we were.. I guess while spinning the knobs he lost his air picture but once we turned back on final from about 10 miles away and the runway popped up he looked more comfortable .

re pulling “g”, not many people believe me but I used to be 6’ 2 😃😃

 

 

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On 1/21/2020 at 5:44 PM, Don Hudson said:

...I used to offer that to F/Os on their leg, sometimes with a nudge but no one took up the offer. Engaged the a/p at 400', click-click at 400' on the other end...

I hand-fly to about 14 000 most departures, and find that the FOs that need the practice the least, do the same.  To be clear, I do need the practice.   Perishable skill and all.

Agree not many 738 overruns due braking performance.  Landing fast is not ideal but can be managed.  Land long, and there's not much hope of staying on the hard surface.  Land long, and there's a higher chance other items will be delayed or forgotten, like reverse thrust. 

Given the sheer number of 738 overruns, you'd think Boeing and the airlines would hasten towards implementing and installing RSAT/ROPS or some version thereof.  I don't think it's a matter of changing SOPs, and I'm not optimistic pilot technique will improve, once again a technology might help, like EGPWS and TCAS.

Boeing Runways Situation Awareness Tools

Airbus Runway Overrun Prevention System

 

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Turkey plane skids off runway and splits in Istanbul

The plane after skidding off the runwayImage copyrightGETTY IMAGES Image captionThe plane broke into parts after skidding off the runway

A passenger plane has skidded off the runway at an airport in Turkey and broken into three pieces, officials say.

The jet was reportedly carrying 177 passengers and six crew when it crashed at Istanbul's Sabiha Gokcen airport.

No-one died in the incident, Transport Minister Mehmet Cahit Turhan said.

The Pegasus Airlines plane was landing in heavy rain after flying in from the western province of Izmir, Turkish media reported.

Passengers were led off the plane but officials were working to free some still stuck on board, officials said. There are believed to be injuries.

Videos circulating on social media show a fire inside the aircraft although the blaze was later put out by firefighters.

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Plane crashes at Istanbul airport after landing

Part of the plane caught fire as a result of the accident

 

turkey-plane-Getty.jpg?ve=1&tl=1

ISTANBUL, TURKEY: Officials work around the site after a passenger plane skidded off the runway in Istanbul Sabiha Gokcen International Airport, breaking into two, on February 05, 2020 in Istanbul, Turkey. (Photo by Istanbul Security Directorate / Ha

ISTANBUL, Feb 5 (Reuters) - A plane flying into Istanbul's Sabiha Gokcen airport from Izmir skidded off the runway after landing and crashed on Wednesday, injuring 21 people, Turkish officials said.

GET FOX BUSINESS ON THE GO BY CLICKING HERE

The plane split into three pieces after what Transport Minister Cahit Turhan called a rough landing, adding that there were no fatalities. He said flights waiting to land in Sabiha Gokcen were diverted to Istanbul Airport.

 

plane-Istanbul-Getty.jpg?ve=1&tl=1

A Pegasus Airlines Boeing 737 plane after it skidded off the runway at Istanbul's Sabiha Gokcen airport (Photo by Muhammed Demir/AFP via Getty Images)

A spokeswoman for Pegasus Airlines confirmed the crash but did not provide further details.

Istanbul Governor Ali Yerlikaya said the plane was carrying 171 passengers and six crew members from Turkey's western province of Izmir.

Emergency response teams had taken 21 people to hospital and evacuation efforts were continuing, Yerlikaya said.

 

plane-Istanbul-Getty-001.jpg?ve=1&tl=1

ISTANBUL, TURKEY: Officials work around the site after a passenger plane skidded off the runway in Istanbul Sabiha Gokcen International Airport, breaking into two. (Photo by Adem Koc/Anadolu Agency via Getty Images)

Footage on Turkish media showed the plane's fuselage, as well as a section of it near the tail, had broken off. Passengers were being led out as the plane lay on a patch of grass next to the runway. Dozens of emergency response personnel were taking passengers out of the plane and carrying them away on stretchers.

Earlier footage showed part of the exterior of the plane had caught on fire, which Anadolu said was put out by firefighters.

Turkish Airlines said it canceled all its flight in and out of Sabiha Gokcen on Wednesday.

CLICK HERE TO READ MORE ON FOX BUSINESS

(Reporting by Ali Kucukgocmen and Ezgi Erkoyun in Istanbul, Tuvan Gumrukcu in Ankara; Editing by Dominic Evans and Jonathan Spicer)

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An update with a photo showing the left side of the aircraft and the cockpit. The nose section appears to be upside down.

Dozens injured as plane skids off Istanbul airport runway

The plane was carrying 171 passengers and six crew members from Turkey's western province of Izmir.

40 minutes ago
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The airport was shut down and flights were being diverted to Istanbul's main airport [Murad Sezer/Reuters]
The airport was shut down and flights were being diverted to Istanbul's main airport [Murad Sezer/Reuters]

A plane flying into Istanbul's Sabiha Gokcen International Airport has skidded off the runway after landing and crashed, injuring at least 52 people, Turkish authorities said.

The plane crashed into a field and broke into three pieces on Wednesday. Passengers were seen evacuating through cracks in the plane.

Istanbul Governor Ali Yerlikaya said at least 52 people were injured in the accident. His office said the plane was carrying 171 passengers and six crew members from Turkey's western province of Izmir.

The airport was shut down and flights were being diverted to Istanbul's main airport, he said.

A spokeswoman for Pegasus Airlines confirmed the crash but did not provide further details.

The accident comes a month after another Pegasus plane skidded off the runway in Istanbul at the same airport. There were no deaths or injuries in that incident on January 7.

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