737 runway overruns

[ATIS]

I've currently got my marching orders to convert from A320 to B737.

Having never flown a 737 before, I'm becoming concerned with the number of overruns on the 737. Just looking at Aviation Herald indicates 2 incidents this past week alone, Aqaba and Mumbai. They generally occur in the rain. So is the 737 susceptible to aquaplaning?

[Chesty Morgan]

No, it's susceptible to poor handling and idiots. Just like any other aeroplane.

[PEI_3721]

Chesty, your opinion; but where is the well-reasoned evidence justifying this ‘opinion’?

If we look for an association of runway overrun incidents and aircraft type then we will probably find it - bias.
Similar bias exists with cause; we tend to blame the pilots as ‘an easy’ option without fully considering the factors which could affect human performance. These factors should include the aircraft type, the method and ease of system operation. When all of the factors in overrun accidents are considered for relevance to a particular aircraft type then there may be links: aircraft type, type of accident. However, I suspect that there is insufficient data or lack of expertise or time to support such an evaluation, but considering ‘what if’ is good place to start.

‘Why’, or ‘why not’ would be good questions in ground school; and if you are really brave you could question particular SOPs, but then you might need good supporting arguments for an alternative view.

[B2N2]

The Boeing 737 is the work horse of the aviation industry with 9,700 built to date.
Simple statistics will show us that the majority of single aisle narrow body accidents will be.....737's...
You come from the Airbus you say:

For the entire A320 family, 118 aviation accidents and incidents have occurred (the last one being Afriqiyah Airways Flight 209 on 23 Dec 2016), including 35 hull loss accidents (the last one being EgyptAir Flight 804 on 19 May 2016),and a total of 1393 fatalities in 17 fatal accidents (the last one aboard EgyptAir Flight 804 on 19 May 2016).

Unfortunately for both types the same applies, unscrupulous operators cutting cost on training and outright corruption at Aviation Authorities.

[B2N2]

The Boeing 737 is the work horse of the aviation industry with 9,700 built to date.
Simple statistics will show us that the majority of single aisle narrow body accidents will be.....737's...
You come from the Airbus you say:

For the entire A320 family, 118 aviation accidents and incidents have occurred (the last one being Afriqiyah Airways Flight 209 on 23 Dec 2016), including 35 hull loss accidents (the last one being EgyptAir Flight 804 on 19 May 2016),and a total of 1393 fatalities in 17 fatal accidents (the last one aboard EgyptAir Flight 804 on 19 May 2016).

Unfortunately for both types the same applies, unscrupulous operators cutting cost on training and outright corruption at Aviation Authorities.
To be honest I find the question somewhat ignorant, coming from a professional pilot.

[FlightDetent]

The previous generation -3/4/500 did mostly have steel brakes. Carbons are a whole different league. The second hand-market for 737s exists for good 30 years, A320 probably 18? I am pointing towards the existence of 4th to 5th hand market, and the associated operators. In essence, Chesty's wrapped it neatly.

Boeing 737 Accident Reports (http://www.b737.org.uk/accident_reports.htm)

B2N2: 7900 buses soldered too. 1:1.2 I did not count the lines here: https://en.wikipedia.org/wiki/List_of_accidents_and_incidents_involving_the_Boeing_737, but it is moot as long as hijack and similar incidents are included. Pot/kettle?

Personally I find the question valid, especially from a professional pilot getting ready to excel again. I spent my first 3 years buried in accident reports after getting type rated the other way, education and knowledge never hurts.

To stay not far from the topic, an anedcote: there was a runway excursion of an Airbus at rather high speed of about 50 knots, the crew managed to drive through the apron, and enter the runway in opposite direction before stopping. Luckily the helo pilot blocking their re-joining taxiway pulled out :E in time! There's much to learn on how (not to) operate the type in that paper.

While reading some other reports, it does not make much difference, I concurr. Toronto A340 and Jamaica 737 is a classic duo.

[RAT 5]

B737 family. A pilots' aeroplane. It is not a playstation.

[Chesty Morgan]

Chesty, your opinion; but where is the well-reasoned evidence justifying this ‘opinion’?

The 737 is, in essence, just like any other aeroplane. Handle any of them poorly or put an idiot in the seat then things will likely go wrong.

Evidence? Plenty of tales of woe out there.

[FlyingStone]

737 generally doesn't like to be landed half down the contaminated runway, with speedbrakes not armed, selecting reverse 10 seconds after touchdown with VREF + a lot, using lower flap setting and one reverser inop.

Which is how most of those overrun reports go (regardless of aircraft type I might add).

[pattern_is_full]

At the time of the 2009 American 738 overrun in Kingston, Jamaica, it was pointed out on this forum (not by me) that the geometry of the "stretchiest" 738/9s - the angle between the gear and tail - meant less leeway for avoiding tailstrikes, and thus perhaps a tendency to land with less AoA/pitch and higher speed.

The A320 family have taller landing gear and thus a slightly more generous tail clearance.

https://en.wikipedia.org/wiki/Boeing_737#/media/File:B737Familyv1.0.png

https://en.wikipedia.org/wiki/Airbus_A321#/media/File:A32XFAMILYv1.0.png

However, I'm in total agreement with the previous posts - unless one filters and cross-references overrun events for a host of other factors: runway length, runway slope, weight, weather, fleet size, crew training, operator quality, specific aircraft subtype, etc. etc. - that is a difference that may not really make a difference.

The Kingston event involved not just a wet runway and a 738, but also a tailwind barely within limits and a late touchdown (4000 feet/1200 meters/halfway down the runway).

[B2N2]

737 generally doesn't like to be landed half down the contaminated runway, with speedbrakes not armed, selecting reverse 10 seconds after touchdown with VREF + a lot, using lower flap setting and one reverser inop.

Which is how most of those overrun reports go (regardless of aircraft type I might add).

This ^^^
And hydroplaning not being a function of airplane type :rolleyes:

[CallmeJB]

Vref is usually set at 1.3 Vs.

Do the 737 or A320 family ever use Vrefs that are higher than 1.3 Vs? I don't mean wind correction and those things, I mean a systematic increase based on tail clearance or the like.

If one type uses an artificially higher Vref, then that should be identified as a 'threat' to safe landings. It's nothing that can't be mitigated, but something that should be considered by the OP.

[misd-agin]

Vref's are actually 1.21(?) to 1.3 Vso. The 737-800 Vref is about 1.29 Vso F30 and 1.24 Vso F40.

As Flyingstone mentioned how overruns have occurred if the plane is flown correctly?

[oceancrosser]

B737 family. A pilots' aeroplane. It is not a playstation.

737. Not this pilots airplane. And I have flown it from both seats.

[PEI_3721]

“And hydroplaning not being a function of airplane type”
But hydroplaning is related to the type of tyre and tread depth (which may be related to the aircraft maintenance manual).
The hydroplaning speeds of many modern tyres do not corespondent with general rules of thumb (9/P), often with a wider spread of speeds.

Was the 737 thrust reverser mechanism changed to give greater airborne integrity after the Lauda accident ?
Was there any effect on the ease and reliability of ground selection; does this differ from other types ?
Does the 737 landing performance over-rely on thrust reverse ?

[Check Airman]

Interesting question. Poor technique will bite you in whichever airplane you're in. I suppose the question is, is the 737 particularly unforgiving when compared to the direct competitor, the A320?

The fact that there are more 737s shouldn't make it particularly hard to do the analysis. If we restrict the time period to the past 10-15 years, we have more than enough data to see if there's a statistically significant difference between the two types per 1000 hrs or 1000 sectors.

[Doors to Automatic]

The B737-800 generally has a higher approach speed than the A320 especially at Flap 30 (which is, I understand more commonly used than Flap 40) so I would hypothesise than given equal numbers of idiots at the helm, it would be involved in marginally more overruns than the Airbus.

Am happy to be corrected though.

[misd-agin]

Max landing weight -

Required landing distance for the A320 F Full is only 31' less than the 737-800' F30. With F40 the 737-800 is about 149' less than the A320.

The A321 F4 Full is 297' more than the 737-800 F30 and 487' more than the 737-800 F40.

Any study would have to look at airplanes operated, and flown, correctly.

They're airplanes, neither model is not that much more difficult to fly than the other model.

[Check Airman]

Any study would have to look at airplanes operated, and flown, correctly.

They're airplanes, neither model is not that much more difficult to fly than the other model.


I agree with most of what you say here, but I think a first study should just compare the accident/incident rates, before we can start digging into why.

For example, let's say X% of 737 overruns were due to excessive speed at the threshold- we could lump that into "improper operation".

We'd then need to go a layer deeper and find out how that number compares to Airbus planes. Which fleet has a higher percentage of unstable approaches?

The third layer would determine why the 737 speed was high in the first place. Is it that much harder to slow? Is it better to recommend F40?

[Derfred]

Does the 737 landing performance over-rely on thrust reverse ?

It does when you're aquaplaning. :}

[FlyingStone]

Was there any effect on the ease and reliability of ground selection; does this differ from other types ?

It does. You don’t even need to be on ground in order to select (idle) reverse.

[PEI_3721]

#22, interesting.
Re “… would have been able to stop the airplane on the runway if …”

There are many accident reports echoing this point; ‘the aircraft operated as designed’, … ‘the crew did not use it correctly’; blame, train. There is little consideration that even a well trained crew might not be able think of adjusting a system operation in critical situations.
After an event the investigator can calculate distances in slow time; during the event the crew would have to fully understand the capability of the aircraft in the actual conditions, not necessarily as reported, and compare achievable landing performance with runway remaining, a change of action if required.
We forget that humans are more often a limiting factor in an man-machine system, and that on occasion a good machine is insufficient to protect the human, be that operator, runway assessor, regulator, or designer.

There are many situations where the industry should not use the human as the safety back stop;- just because pilots are the last link in the chain does not mean that it is the best defence.
Generally additional safety margins are applied in these situations; landing distance margin.
Historically, the US system, manufacturer, regulator, operator, applied landing distance margins based on ‘actual’ data, where only a minimum addition was required. Other countries had a range of methods, some followed the US example, others - Europe, biased towards the AFM and larger factors.
Nowadays the industry is moving towards commonality with OLD/FOLD (although minimum factors still reign). There may be a pattern involving the 737 in this, but it could be difficult to identify amongst the many variables. A starting point could be what is taught by the manufacturer;- dispatchers use a performance manual (AFM data), flight crews the FCOM (actual data).

[safetypee]

I recall a formal study comparing the safety level of aircraft landing performance between those aircraft with thrust reverse and those without.
Much as expected those aircraft without reverse had less overall safety margin - not sure how that was defined.

I also recall a follow-on study considering the failure of reversers to deploy. Here the aircraft with reverse (failed) had the lesser safety margin. And with fast fading memory, the 737 did not fair particularly well (anyone have a reference for this report).
A conclusion was that the 737 thrust reversers contribute more to the landing performance than other aircraft, the 737 being less able to stop than other aircraft without reversers.
Ratio of effectiveness - reverse vs brakes anyone?
Size / capacity of brakes, brake materials, type of anti skid.

From an HF aspect perhaps those crews operating aircraft without reverse are more risk aware than those who can select reverse - but not necessarily safer. But if reverse fails …

[tdracer]

It might be worth remembering that, at least in the FAA world, the landing performance distances give no credit for thrust reversers (EASA is a little different but I don't know details).
FAA landing distances are established by landing on a dry runway with max braking and no T/R. This is done multiple times at different landing weights to establish a weight/distance baseline. Then a factor is applied - a rather large one (2.4 comes to mind but don't hold me to that) - to account for things like low friction runways and less than perfect technique.
Any improvement the T/Rs provide is considered a bonus.

[safetypee]

td, No credit for T/R
That's correct for certificated performance as in the AFM, which already includes a ‘dry’ factor. The AFM data and further factoring (wet) is predominantly used for dispatch; whereas ‘actual’ - unfactored performance is in the FCOM for crew use, and more often includes credit for T/R.
The impression I have is that operators who use ‘actual data’ tend to include T/R as standard and then consider the minimum FAA factor of +15% on top. Like most landing data this is satisfactory if the runway condition is as reported, but if the braking action is less than planned, then (factored) actual data may run out of runway earlier than other factored data. Do 737 operations predominantly use ‘actual’ data?

A 2.4 factor was published in a Canadian report re landing on snow and ice, grooved / ungrooved runways, assessing equivalent safety with dry operations (IIRC they used a 737), i.e. using anything less than 2.4 on ice and snow has a higher risk than normal.

FAA and EASA are harmonised for AFM data, except EASA has additional requirements for contaminated operations. For operating data, EASA has moved rapidly towards Factored Operational Landing Distance lead by manufacturers (is 737 data available yet - all versions ?). FOLD is much more realistic than ‘actual’, but may be less than AFM factored data, although some views argue that there is a good correlation between FOLD and AFM for a wide range of operating conditions - is more tolerant of miss reporting braking action.

P.S. Aviation Investigation Report A10A0032 - Transportation Safety Board of Canada (http://www.tsb.gc.ca/eng/rapports-reports/aviation/2010/a10a0032/a10a0032.asp#fnb52-ref)
(727), para 1.9 discusses additional factors (up to 2.4) in very wet conditions, with/without T/R.

TC Reference. History of the Joint Winter Runway Friction Measurement Program. TP 13579
From Joint Winter Runway Friction Measurement Program - Transport Canada (http://data.tc.gc.ca/archive/eng/innovation/tdc-projects-air-f-9048-92.htm)

FAA position re improved data https://www.aci-na.org/sites/default/files/talpa_cast_brfng_8-4-16.pdf still only advisory, whereas EASA mandates it.

[Centaurus]

A picture is worth a thousand words, so the saying goes. I believe that; which is why when telling type rating candidates that reverse is more effective at high speed I use the following demo in the simulator.

For example: 737 Classic. Take off on slippery runway surface ice patches (input into simulator). Flaps One max structural weight with all engines abort at 150 knots on 10,000 ft runway sea level nil wind.
First abort using speed brake and brakes only. No reverse. Result was over-run the end at 30 knots.
Second abort: Full reverse at 150 knots. No brakes and no speed brake. Over-run about 30 knots as well.
Third abort: 150 knots Maximum manual braking. Speed brake and max reverse. Aircraft stops on runway about 300 metres from the end.
Conclusion: It was the full reverse (plus brakes and speed brake) that made the difference and permitted the aircraft to stop with room to spare.

Admitted freely that this was an amateur and unmeasured attempt to prove reverse at high speed is more effective for stopping than at low speed. Candidates were convinced.

[CaptainMongo]

I'll add my .02¢.

No one behind the cockpit door knows the definition of a good landing, not one of them. To them a smooth landing is a good landing, we know better.

A smooth landing 3000' down the runway is, IMO, is a legal but bad landing. A smooth landing 3001 feet down the runway (or first 1/3 whichever less) according to our manuals constitutes an unstable approach and a go around must be performed.

A firm touchdown at 1000' may not get you any attaboys from anybody behind the door, but it will get a positive comment from me.

If we strive to touchdown at 1000' on each and every landing, when the time comes where we really, really need to we know we can because we do it every day. Do I try to touchdown at 1000' feet on every landing, yup, am I successful doing that on every landing nope, so I keep practicing.

[Centaurus]

A firm touchdown at 1000' may not get you any attaboys from anybody behind the door, but it will get a positive comment from me.

If we strive to touchdown at 1000' on each and every landing, when the time comes where we really, really need to we know we can because we do it every day. Do I try to touchdown at 1000' feet on every landing, yup, am I successful doing that on every landing nope, so I keep practicing.



1000 ft touch down subject. Some history. A former Boeing instructor pilot joined our company in 1976. He had flown during WW2. We operated into Pacific islands with unsealed and sealed coral runways between 4500 ft and 6000 ft length. All slippery after heavy local rain. The Boeing instructor would land quite hard right on the 1000 ft markers every time. Then full reverse.
Passengers often complained about his landings, but he countered by saying that at Boeing, pilots from third world countries frequently underwent 737 type ratings; including on the real aircraft as well as simulators. Firm, little flare but firm consistent accurate touch downs on the 1000 ft markers was Boeing policy; especially as flying competency varied widely among foreign crews.

[john_tullamarine]

.. and, if one doesn't land by shortly after the 1000ft markers, then one is eating into the 1.67 AFM pad ... eat too much and too leisurely and one might get egg on face syndrome if the runway is getting towards being landing distance critical.

As to using actual, rather than AFM, data on the line .. utter madness in this certification engineer's/pilot's view .. just asking for a screw up sooner or later. If it's good enough to use factored data for planning, then it's good enough to use that on the line other than in an emergency situation. Dinosaur ? .. you bet.

[oceancrosser]

Excellent point JT! Been on the same aircraft now for 17 years in the left seat. Now all of a sudden we need to calculate landing perf for every landing. And it is not as we are runway limited anywhere!

-another dinosaur

[pineteam]

A smooth landing 3000' down the runway is, IMO, is a legal but bad landing. A smooth landing 3001 feet down the runway (or first 1/3 whichever less) according to our manuals constitutes an unstable approach and a go around must be performed. .

I don't know who writes such manual but I doubt they are pilots..I agree if you are concerned about landing distance available. But a light A320 with 3500M+ runway on a perfect day.. Who cares if you land slightly deep when you know you only need half the runway to stop the aircraft safely... not saying you should disregard the TDZ, but if the guys floats a little bit, I'm never asking him to "put it down" like some captains Love to do.. Give the guy a break. It's all about common sense. Especially now with the ipad computation, we know exactly what's our margin.. A go around is not always the safest manoeuver. Emirates knows best with their 777 accident... and I know very well about landing on very short strips. I did bush flying before. :p

[Doors to Automatic]

Pineteam - Your post has reminded me of the BA internal pilot safety report I once saw where the go-around of an A319 at LHR was discussed. They floated on landing and when it became evident that they would just miss the last TDZ marker, they went around. The discussion centred around how sound that decision was, and that this should always be the case if touchdown within the TDZ wasn't certain.

The distance to go on the runway in question (27R) at the point the g/a was initiated was circa 9,800ft, which to put into context is twice the length of runway after the correct touchdown point at Jersey where the A319 regularly operates and around 3x what is required to stop.

I did question the wisdom of such a strict SOP but, as my friend (a 747 skipper) said, safety is paramount with no exceptions.

[Fair_Weather_Flyer]

I've flown the 737 for a few years now. The one thing I have noticed is that pilots tend to avoid the advice given in the FCTM as to how to land the aircraft. Boeing is very detailed in its advice; I'll let you look it up and it does work well. No floating and no crashing down, works every time. Yet many pilots seem to like to yank back, chop the thrust, then yank back some more. Thump it on, float it or grease depending on the day. With a slippery or contaminated, shortish runway the floater guarantees trouble.

There are lots of overrun accident reports you could look at. I'd suggest the Southwest Airlines Chicago Midway, Southwest Airlines Burbank and Eastern Airlines La Guardia reports may give food for thought.

[vilas]

Pineteam
Landing distance is one issue which will be satisfied by long runway but if you float tail strike comes in picture. One needs to follow percentage technique. Because on one day A320 is fine but on another day same thing in A321 will cause tail strike. So the adage greasers are good for passengers but not pilots

[Centaurus]

but if the guys floats a little bit, I'm never asking him to "put it down" like some captains Love to do

Telling the PF to "put it down" (during a long hold-off) is asking for trouble. That can lead to "spiking" the aircraft nose-wheel first and a bounce is the likely result. It is usually a nervous captain saying "put it down" as I can not visualise a first officer demanding that if the captain is landing.

If for some reason let's say the first officer is the culprit of the long float, the captain, rather than risk attempting to salvage a bad situation by talking the PF into "putting it down", should promptly take control and go-around.

Telling the first officer to go-around instead of taking over control of the go-around himself, has the potential for a further critical delay. Especially if there is a language difference between the two crew members which has the potential to further exacerbate an already developing situation.

Bugger whose "leg" it is. There are times when a stuff-up has occurred and that is where the captain needs to recognise his own responsibility for the safe operation of the flight and take control without pondering the why's and wherefore's of whose "leg" it is.:ok:

[pineteam]

Pineteam
Landing distance is one issue which will be satisfied by long runway but if you float tail strike comes in picture. One needs to follow percentage technique. Because on one day A320 is fine but on another day same thing in A321 will cause tail strike. So the adage greasers are good for passengers but not pilots

Hello Vilas,

I totally agree with you. I'm only flying on the left less than 4 months since training is completed and so far, I never had that situation yet nor a situation that I felt like I had to take control. But I definitely have what you say in mind. I can only fly with senior Fos for the first year. Make life easier for sure. Not meaning bad landing can't happen of course, it does happen to all of us. We fly A319, A320 and mostly A321 and from my little experience so far I only had one "hard landing" of 1.78g on an old A 321. The guy did not flare enough. Still a safe landing tho.:}

[CaptainMongo]

I don't know who writes such manual but I doubt they are pilots..I agree if you are concerned about landing distance available. But a light A320 with 3500M+ runway on a perfect day.. Who cares if you land slightly deep when you know you only need half the runway to stop the aircraft safely... not saying you should disregard the TDZ, but if the guys floats a little bit, I'm never asking him to "put it down" like some captains Love to do.. Give the guy a break. It's all about common sense. Especially now with the ipad computation, we know exactly what's our margin.. A go around is not always the safest manoeuver. Emirates knows best with their 777 accident... and I know very well about landing on very short strips. I did bush flying before. :p

We have about 300 instructors, standards Captains and management pilots in our training center, they write our manuals.

Our stabilized approach criteria as is our abort criteria are independent of runway length. When you brief your companies abort criteria, do you make caveats for runway length? Something like, "Hey I know we aren't suppose to abort above V1 but we are taking off on a long dry runway so..."

Accident reports are littered with the bodies of pilots (and passengers who wished to remain uninvited to their own funerals) who thought SOP doesn't apply to them, or SOP was for less accomplished pilots, or SOP was situation dependent.

Intentional non compliance is a cancer our industry can not afford.

[pineteam]

V1 is not only a limitation by runway lengh... anyway I won't argue. We don't have such restriction in our Sop. So I don't break any rule... once again it's common sense. If you wanna do a go around at 30 feet on a 4000 meters runway just because you pass the 900 meters TDZ, be my guest... LOL I'm gonna land cause I still use my brain and it's telling me it's safe!😜

[Intrance]

With all due respect... Better to reinforce the good habit of landing where you are supposed to land, than risking creating a possible bad habit of landing beyond 900m. Just using my brain in a different way than you do.

I don't really see what's to gain in landing long intentionally and I see all kinds of potential risk in it. One day on the last sector of a max FDP day, you might forget that this airport is actually not a 4000m runway but 3000m or even less. And obviously that will also be the day that you are at max landing weight and upon touchdown reversers fail to deploy, spoilers have a day off and/or your brakes are having a ****ty day. Because Murphy.

You have XXX number of people in the back that are your responsibility, why degrade safety margins? Yes, 9 times out of 10 it will probably be fine, I'll just be landing with that tenth one in mind. Just two cents.

[pineteam]

We always do ipad computation for landing performance so our situation awareness for the landing distance is there... Maybe I was not clear enough: I don't land deep on purpose. It's very rare that I have landed after the TDZ. Of course not, we are professional pilots, or trying to be. I'm just saying that if it happens, most of the time it's safer to continue and land than doing a go around. Most of our incidents in our company happened during a go around. I used to fly in Zambia with extremely short runways, normal runways and long runways... you just don't forget when runway is short. You think about it all the time haha. It's like when you drive at night, you don't forget to turn on the lights don't you? Anyway that's just my point of view. It just amazed me how some pilots can be so conservative and afraid of things going ugly and always overthink like: "If that happens" syndrome. Just fly the plane, relax but be sharp and enjoy. Easy life.

[aterpster]

TWA's touchdown target from the threshold was:

Narrow body: 500-1000 feet
Widebody: 1000-1500 feet

A PIC exceeded those parameters at his/her peril.

[RAT 5]

Telling the PF to "put it down" (during a long hold-off) is asking for trouble. That can lead to "spiking" the aircraft nose-wheel first and a bounce is the likely result. It is usually a nervous captain saying "put it down" as I can not visualise a first officer demanding that if the captain is landing.

I found many pilots were not advised how to 'put it down'. If it became necessary it was often caused by too much back elevator; thus the answer was to relax the nose and land flat; or worse. The other danger is pulling back even more. My technique, if tending to float a couple of feet above the tarmac, was to 'drop a wing', remembering of course where the wind was. Immediately a main wheel touches down the speed brakes deploy and the a/c sits down.
It's a simple technique, it works, and is not emphasised; but I used to teach it.

[pineteam]

Hello RAT 5,

Very true. What you say works so nicely. Very helpfull especially with the ones equipped with Sharklets who are good gliders haha. One little push on the side and it goes down smoothly. Also learned that one from colleagues but not officially from instructors during initial training.

[RAT 5]

Also learned that one from colleagues but not officially from instructors during initial training.

And I've always wondered why not. It works for most a/c. We're talking a couple of feet off the deck, not 6 feet. Boeing does write the x-wind limitation for side-slip only approach & touchdown due to trailing edge outboard flap grond contact. I wonder if they are too nervous to include our little 'piloting technique' as there will always be some who mis-interpret it and infringe that other limit. We're back in the circular discussion about training pilots not monkeys. All has to be for the lowest common denominator. It would be nice to raise the bar so the lowest was still a high standard. But that's for another day's debate over a cold one.

Still, for instructors to pass it on, like many other 'unofficial' tips & tricks, seems a proactive move to prevent some over runs, especially on the short runways B737's often operate into. Sitting there floating in ground effect hoping that the beast will settle in time, and wondering why you didn't use F40 in the first place, and wondering if there was a gem of an answer to help the dunlops meet the tarmac PDQ is not a cosy predicament, when there is a little gem.

[vapilot2004]

737 generally doesn't like to be landed half down the contaminated runway, with speedbrakes not armed, selecting reverse 10 seconds after touchdown with VREF + a lot, using lower flap setting and one reverser inop.

Which is how most of those overrun reports go (regardless of aircraft type I might add).

Agreed FS :ok:

Planting oneself halfway down a contaminated runway is usually cause enough - for any transport category aircraft.

[Doors to Automatic]

[I] My technique, if tending to float a couple of feet above the tarmac, was to 'drop a wing', remembering of course where the wind was. Immediately a main wheel touches down the speed brakes deploy and the a/c sits down.
It's a simple technique, it works, and is not emphasised; but I used to teach it.

Talking of unofficial techniques to get a plane down, I was once bawled out of a thread here for suggesting that the spoliers could be pulled slightly if an aircraft was floating. Imagine my surprise when I read that a 737 was prevented from overrunning at Grand Cayman when this very technique was employed after a float!

[misd-agin]

Would a g/a resulted in a crash? Or would a g/a have been the more prudent choice?

[BARKINGMAD]

What are the statistics for undershoots for similar types over the same sample period?

Once upon a time Bae146-300 series were landing at Berne, 1300m of runway and none of this 300m wasted real estate merde!

Then all runways were fitted with PAPIs for long-bodied aircraft and we were all forced to aim further down the concrete.

Then people like Mr Boeing insisted on factoring the approach speeds with half STEADY headwind component up to Vref+20kts even though windshear was not necessarily present.

Add to these the average performance of line dogs, some of whom should not have been in the front seats and hey presto we have numerous excursions onto the inhospitable terrain in the overrun area with inevitable hull losses and fatalities/injuries.

It's purely an energy management task corrupted by some rather odd presumptions about how the 'frame behaves in IAS and infection by the large eye-wheel brigade.

Why is the runway threshold marked by "piano keys" and are there any medium category jetjocks out there capable of dropping the 'frame onto the concrete just beyond said markings?

Awaiting the undershoot stats with my tin hat on................🙄

[RAT 5]

Ah Ha. Now I remember why my PPL had a 'short field landing' included in the test. The last time, on a short runway, I retracted the flaps on my Boeing, before I had vacated the runway, my name was up before 'The Beak' ASAP. But sir, I cried................:)

[Centaurus]

my PPL had a 'short field landing' included in the test

Short field landings were a wartime military teaching and never meant to apply to civilian flying school syllabus of training. That was because war time emergency landing grounds could be of unknown or un-measured lengths and to touch down at the absolute min safe speed was important. Landing on aircraft carriers was an example.

Since most instructors who came back from the war became civilian flying school instructors because of lack of available jobs in the start-up airline industry, these instructors taught what they in turn were taught by military flying instructors. Usually the technique was to knock off 10-15 knots from the normal over-the-fence IAS and plonk it on the threshold and slam on the brakes and hey presto there was your short field landing.

Try knocking off 10 knots below Vref in the Boeing and Airbus and as you say it is tea and bikkies with the chief pilot.

Nowadays short field landings on singles and twins are still required to be demonstrated for the PPL and CPL as per CASA syllabus but speeds used are as per normal threshold speeds from the AFM or POH. Knock off 10 knots over the fence in the CASA test and you fail. Then join an airline and there is no such thing as a short field landing in an airliner - not legally, anyway.
There has been no attempt by CASA to delete the syllabus requirement for a demo of a short field landing for the PPL and CPL tests. It is long overdue. Caution:) All the above is IMHO.

[framer]

I like barkingmad's theory. When did Papi's come to n the scene?

[RAT 5]

Centaurus: note the 'smilie', as in joke, at the end of my post. I think you took it too seriously.

[BARKINGMAD]

C'mon folks, concentrate?

Read my original post and then work forwards from when jet transports were landed close to the threshold with minimal additions to Vref/Vapp until the current scene where 300 metres of paved runway real estate are wasted and for some odd reason a headwind is regarded as a special case requiring extra knots of IAS even though shear/turbulence is NOT a factor.

Probably I'm biased as my first post-military job was the Bae146 where the manual clearly stated "in order to make the scheduled landing distance...cross the landing threshold at Vref (airbrakes fully deployed) aiming to touchdown at Vref-7kts". Yes, that hyphen was a minus sign!

Whilst I appreciate the Boeings various may not use airbrakes whilst airborne, my abiding memory of transitioning onto the 74s and then 73s is that flying even at Vref over the landing threshold caused apoplexy amongst trainers and experienced capts, so that the only way to avoid criticism was to arrive at the threshold with minimum Vref+5kts and then everyone was happy.

Which has left me wondering why Boeing mentions Vref at all if it's never used. I suspect a ruse to get the paper Vref down to such a value in order to allow the approach Category of the 'frame to be listed as 1 below where it belonged.

There may now follow much discussion of 1 point something the stalling speed in the particular configuration depending on whose airworthiness or XAA regulations one is following, all I'm asking is a reasonable explanation of why the world's overruns are littered with disasters whereas the odd undershoot doesn't seem to feature in the stats. Please don't quote the San Fran disaster, they were just exploring a place all competent jocks wouldn't dream of going!

Maybe the airports' runway inspection routines may show up some inadvertent early (short of 300m) tyre marks but I would suggest this is less likely to happen if the guilty drivers had the orifice-puckering sensation of rocks/grass/gravel/lights/beach underneath them as they aim for the proper medium category transport touchdown point?

Still awaiting the comparison of stats to disprove the old adage that "there's nothing as useless as...the runway you've left behind".

But in the bright new dawn of the 21st century there are old lessons in aviation which are being forgotten.

In summary, the original posting asked about 737 overruns and I'm posing "why so fast and why so far in?" And we haven't even got to the tailwinds cases!

:suspect:

[RAT 5]

... my abiding memory of transitioning onto the 74s and then 73s is that flying even at Vref over the landing threshold caused apoplexy amongst trainers and experienced capts, so that the only way to avoid criticism was to arrive at the threshold with minimum Vref+5kts and then everyone was happy.
Which has left me wondering why Boeing mentions Vref at all if it's never used.

I understand your comments. Surely the 1000' aiming point is to ensure a gear clearance height over the threshold and thus the approach lights shortly there before. Plonking it on the numbers with the gear many meters behind you and feet below is a challenging task fraught with tears.

In Boeing's FCTM they suggest a technique that is challenging and probably rarely achieved. Cross the threshold at Vref +5 + headwind & gust and touchdown at Vref + gust. The max addictive is +20. Dream on baby.
The technique suggested doesn't work. You arrive at 50' over the threshold at Vref + add ons. You false at 20' and close the TL's to idle so as to touch down at Vref or Vref + gust. So they some that this single technique can remove +5kts of whatever 1/2 the head wind was, which could be more. How is that possible for a constant drag scenario. If it removes 5kts how can it remove more than 5kts? Also, when committed to the landing, and n the flare, why is all the gust additive so important? For me, after 35 years on Boeing beasts Ive yet to achieve or seen achieved the perfect speed decay in the flare. It is a myth and perhaps only the Boeing sky gods can demo it. I suspect it is a numbers game to plug into the OPT landing performance calculation. Having said that, an over run is not caused by touching down in the correct place a couple of knots too fast; it is more likely caused by touching down too far, even at the correct speed, and then being too tardy with braking. Given all the buffers built into the calculations an over-run has to be either very different wind conditions than expected or gross mishandling; and that includes too fast or too long, usually both.

[Musician]

Having said that, an over run is not caused by touching down in the correct place a couple of knots too fast; it is more likely caused by touching down too far, even at the correct speed, and then being too tardy with braking. Given all the buffers built into the calculations an over-run has to be either very different wind conditions than expected or gross mishandling; and that includes too fast or too long, usually both.
Gerard van Es at the NLR-ATSI (Netherlands Air Transport Safety Institute) has studied runway overruns; on their site (http://nlr-atsi.nl/), there's more than you'll probably care to read on runway excursions (http://nlr-atsi.nl//services/runway-safety/runway-excursions/). From his numbers (http://nlr-atsi.nl//downloads/a-study-of-runway-excursions-from-a-european-p.pdf), the "long landing" is a factor twice as often as "speed too high". Of course a landing can suffer from both. I'm attaching a slide from his 2013 presentation (http://nlr-atsi.nl//downloads/why-do-business-aircraft-go-off-the-runway-mor.pdf) below. Van Es seems to believe that a lot of runway overruns could be avoided if pilots did more go-arounds on unstabilized approaches and these "long flares".

I have no idea what considerations went into the setting of the touchdown standards, but I'd guess that putting the touchdown zone safely behind the threshold means the flare occurs over tarmac: maybe over soft ground, pilots would come out of the flare higher since they'd be afraid of hitting the dirt, and then "float" longer? and the extra 5 knots on the air speeds might be a safety allowance for sudden wind variations?


To get back to the original topic of this thread: the NLR-ATSI runway excursions (http://nlr-atsi.nl//services/runway-safety/runway-excursions/) page also has links to statistics on overruns/veeroffs for select years that show the aircraft type, and they're sortable. Sort first by aircraft type, then by phase and occurrence, and the incidents are easily countable: in 2013, the B737 had 10 landing overruns (and 3 veeroffs), while the A320 had 10 landing veeroffs (and 2 overruns). In previous years, the A320 had a lot less veer-offs, but the B737 overruns had comparable numbers, so the premise of this discussion seems correct.
I have been searching for figures on worldwide departures by aircraft type, but couldn't find any; fleet sizes are not that different, but departure numbers can still vary considerably if a type flies more short sectors. Does it seem plausible that the B737 would have 5 times as many departures as the A320?