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737 runway overruns

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737 runway overruns

Old 20th Sep 2017, 16:16
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737 runway overruns

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?
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Old 20th Sep 2017, 17:18
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No, it's susceptible to poor handling and idiots. Just like any other aeroplane.
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Old 20th Sep 2017, 18:16
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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.
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Old 20th Sep 2017, 18:45
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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.
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Old 20th Sep 2017, 18:46
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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.
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Old 20th Sep 2017, 18:56
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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

B2N2: 7900 buses soldered too. 1:1.2 I did not count the lines here: https://en.wikipedia.org/wiki/List_o...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 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.

Last edited by FlightDetent; 20th Sep 2017 at 19:22. Reason: response to B2N2
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Old 20th Sep 2017, 19:54
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B737 family. A pilots' aeroplane. It is not a playstation.
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Old 20th Sep 2017, 20:18
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Originally Posted by PEI_3721 View Post
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.
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Old 20th Sep 2017, 20:39
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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).
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Old 20th Sep 2017, 23:37
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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...Familyv1.0.png

https://en.wikipedia.org/wiki/Airbus...FAMILYv1.0.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).
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Old 21st Sep 2017, 01:31
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Originally Posted by FlyingStone View Post
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
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Old 21st Sep 2017, 13:11
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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.
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Old 21st Sep 2017, 13:32
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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?
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Old 21st Sep 2017, 17:38
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B737 family. A pilots' aeroplane. It is not a playstation.
737. Not this pilots airplane. And I have flown it from both seats.
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Old 21st Sep 2017, 18:00
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“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 ?
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Old 21st Sep 2017, 19:42
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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.
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Old 21st Sep 2017, 19:45
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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.
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Old 21st Sep 2017, 20:48
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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.
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Old 21st Sep 2017, 23:34
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Originally Posted by misd-agin View Post
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?
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Old 22nd Sep 2017, 07:38
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Does the 737 landing performance over-rely on thrust reverse ?
It does when you're aquaplaning.
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