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# Max Cross-wind component B.737-800

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# Max Cross-wind component B.737-800

3rd Mar 2009, 19:46

Join Date: Nov 2008
Location: winchester
Age: 32
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Max Cross-wind component B.737-800

Can anyone advise the maximum cross-wind component for a B737-800 for landing on a wet runway?
James
3rd Mar 2009, 21:01

Join Date: Nov 2000
Location: Dre's mum's house
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Winglet or non winglet?
3rd Mar 2009, 21:37

Join Date: Nov 2000
Location: Netherlands
Posts: 247
according to our manual 34 kts as long as the reported braking action is good and the runway width is 40 meters. We have no reference to winglet or not.

greetings
4th Mar 2009, 01:42

Aviator

Join Date: May 2001
Location: Norveg
Posts: 482
There are no hard limits. Boeing has issued some recommendations and have tested the aircraft, but those results depended on how strong the winds were during the days of testing. It is up to each operator to figure out how skillful they think their pilots are

For our company: B738 with or without winglets on wet runway = 34kts (TORA/LDA >2.000m) and 30kts (TORA/LDA< 2.000m)
Decrease by 0.5kt per metre of rwy width reduction below 45m.
29th May 2019, 02:10

Join Date: May 2019
Location: glasgow
Posts: 1

Hi James,

Boeing stipulates medium runway conditions (runways saturated with heavy rain) max cross wind factor 25 knots.

Example: Approaching Glasgow Airport using the Lanark 1 ALPHA approach flying a Boeing 737-800

1/ (ATIS reports wind 275/G35-55) captain decides ILS 23 approach giving an offset angle of 40 degrees.
2/ Mean wind = 45 knots.
3/ Approximate calculation using the "sine" of 40 degrees is 0.7.
4/ Multiply 0.7 by mean wind 45 knots = 31 knots.
5/ Compare the actual cross wind factor against the manufacturers stipulated maximum cross wind factor.
Clearly the actual cross wind factor in this example exceeds the manufacturers cross wind limitations of 25 knots for medium condition runways.
6/ Scottish control advises descend to FL50 heading 300 reduce speed 250 knots. Then descend to 2300 feet QNH 1015 cleared for the ILS 23 report localizer
established.
7/ Captain at this stage requests an up to date wind report.
8/ Captain reports localizer established.
9/ Scottish control advises wind increasing 275 gusting 45 to 65 knots
10/ Captain then goes back to his rough mental cross wind calculations and obviously decides to divert.
11/ Captain requests to Scottish control; "request missed approach procedure to holding pattern so to permit time enough to decide best alternative airport?"

Formula. The crosswind component is equal to the speed (V) of the wind multiplied by the sine of the angular difference (XWC = V × Sine ). Therefore, in the example given above (Rwy 21 – W/V 240/20) the angular difference is 30 degrees, and the sine of 30 degrees is 0.5.

Hope this information has been of some use and best of luck for the future.

29th May 2019, 14:07

Join Date: May 2019
Location: Somewhere over the rainbow...
Posts: 0
Despite the manufacturers statement of “max demonstrated” crosswind, there’s more to the suitability assessment than <34 knots good, > 34 knots bad. I’ve landed with a 35 knot steady state crosswind without much difficulty and diverted for less when there was a substantial gust component. Frankly, a big part of the decision process relates to how sharp I’m feeling at that particular moment. After a long day, throw in a little weather, I’m going to be more circumspect about what I will accept.
29th May 2019, 20:29

Join Date: Oct 1999
Posts: 215
Hi James,

Boeing stipulates medium runway conditions (runways saturated with heavy rain) max cross wind factor 25 knots.

Example: Approaching Glasgow Airport using the Lanark 1 ALPHA approach flying a Boeing 737-800

1/ (ATIS reports wind 275/G35-55) captain decides ILS 23 approach giving an offset angle of 40 degrees.
2/ Mean wind = 45 knots.
3/ Approximate calculation using the "sine" of 40 degrees is 0.7.
4/ Multiply 0.7 by mean wind 45 knots = 31 knots.
5/ Compare the actual cross wind factor against the manufacturers stipulated maximum cross wind factor.
Clearly the actual cross wind factor in this example exceeds the manufacturers cross wind limitations of 25 knots for medium condition runways.
6/ Scottish control advises descend to FL50 heading 300 reduce speed 250 knots. Then descend to 2300 feet QNH 1015 cleared for the ILS 23 report localizer
established.
7/ Captain at this stage requests an up to date wind report.
8/ Captain reports localizer established.
9/ Scottish control advises wind increasing 275 gusting 45 to 65 knots
10/ Captain then goes back to his rough mental cross wind calculations and obviously decides to divert.
11/ Captain requests to Scottish control; "request missed approach procedure to holding pattern so to permit time enough to decide best alternative airport?"

Formula. The crosswind component is equal to the speed (V) of the wind multiplied by the sine of the angular difference (XWC = V × Sine ). Therefore, in the example given above (Rwy 21 – W/V 240/20) the angular difference is 30 degrees, and the sine of 30 degrees is 0.5.

Hope this information has been of some use and best of luck for the future.

Oh FFS - you clearly have never flown a commercial airplane...........
30th May 2019, 08:55

Join Date: Mar 2006
Location: England
Posts: 827
Max Demonstrated

yoko1 #6,
‘Max demonstrated’ usually represents the maximum crosswind that the manufacturer has evaluated based on accurate and recorded wind reports, and judged not to be limiting. If higher values are used in service then you are accepting the risk that it could be limiting, particularly that the accuracy of reported wind speeds might be unknown, and in conditions where there could be little margin between just OK and ‘off the side’.

If the manufacturer had tested higher crosswinds and concluded that a particular value or conditions to be unreasonable, i.e. it is limiting, then this value should be published in the aircraft AFM limitations section.

An interesting article relating to crosswind - engine handling, during takeoff
https://safetyfirst.airbus.com/app/t...y_first_27.pdf page 7-

30th May 2019, 09:00

Join Date: Jan 2000
Location: FL410
Posts: 832
Airlines have guidelines for their pilots using OPT (or equivalent) and/or tables to find crosswind component instead of using sine in flight.
An example fo such statement could be:
"To calculate the crosswind component: Enter the table below or OPT with the highest reported wind value (steady wind or gust). Use the angle between wind direction and runway heading to calculate the crosswind component."

Then depending on using this for departure or arrival additional restrictions may be imposed, for example:
"Approach speed correction: Half of the reported steady headwind component plus full gust."

The winglets are not tested by Boeing in same weather conditions as original wing without, possible as discussed due lack of suitable weather conditions during testing.
There is therefore a demonstrated crosswind limit which the manufacturer has published for the original aircraft, while ABP published a maximum for winglets at a later date.
It is up to airline to interpret their guidance on limitations and decide whether to reduce them further for the pilot body to be used.
30th May 2019, 09:08

Join Date: Apr 2006
Location: uk
Posts: 743
For our company: B738 with or without winglets on wet runway = 34kts (TORA/LDA >2.000m) and 30kts (TORA/LDA< 2.000m)
I'm puzzled that the company X-wind limit increases for the shorter LDA; in fact I'm slightly puzzled that the LDA length, as opposed to runway width, affects the X-wind limit at all, although I can see that extra LDA gives more time to touch down safely. But if that's the reason, having a higher X-wind limit for a shorter runway doesn't stack up, at least to this old dinosaur. Can anyone explain, please?
30th May 2019, 11:04

Join Date: Jan 2000
Location: FL410
Posts: 832
Originally Posted by old,not bold
I'm puzzled that the company X-wind limit increases for the shorter LDA; in fact I'm slightly puzzled that the LDA length, as opposed to runway width, affects the X-wind limit at all, although I can see that extra LDA gives more time to touch down safely. But if that's the reason, having a higher X-wind limit for a shorter runway doesn't stack up, at least to this old dinosaur. Can anyone explain, please?
Possibly because the operator takes into account that momentary brake release when weathercocking may be required to regain directional control, thus additional stopping distance may be required?
Just thinking out loud...
30th May 2019, 13:31

Join Date: Jul 2000
Location: My views - Not my employer!
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ONB - I think you're reading his post the wrong way round... Higher crosswind, longer runway...
30th May 2019, 21:05

Join Date: Jan 2006
Location: Between a rock and a hard place
Posts: 1,057
36 kts / 33 kts (winglets) for wet and dry.
31st May 2019, 09:40

Join Date: Apr 2006
Location: uk
Posts: 743
Originally Posted by Cough
ONB - I think you're reading his post the wrong way round... Higher crosswind, longer runway...
= 34kts (TORA/LDA >2.000m) and 30kts (TORA/LDA< 2.000m)
Hmmm......looks to me very much like 34 Kts X-wind limit if the runway is longer than 2000m, and 30Kts X-wind limit if it is less than 2000m, ie shorter runway, higher limit.

Or do I need a dyslexia/dementia/normal age-related confusion test?

Skyjob; Yes, makes sense, plausible, but I wonder if that's the reason.

One possibility is, of course, that Crossunder's little arrows are the wrong way round, ie a forgiveable typo, unspotted since 2009. I hope that a whole generation of B737 pilots who believe that the shorter the runway the higher the X-wind limit wasn't created by that, if it was a typo. There could have been some very exciting landings, with, say, LDA 1200m and 60Kts X-wind component.

Last edited by old,not bold; 31st May 2019 at 10:02.
31st May 2019, 12:33

Join Date: Jan 2008
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Age: 53
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Originally Posted by old,not bold
Hmmm......looks to me very much like 34 Kts X-wind limit if the runway is longer than 2000m, and 30Kts X-wind limit if it is less than 2000m, ie shorter runway, higher limit.

Or do I need a dyslexia/dementia/normal age-related confusion test?
Schedule the test...
31st May 2019, 16:00

Join Date: Jul 2000
Location: My views - Not my employer!
Posts: 966
Originally Posted by old,not bold
Hmmm......looks to me very much like 34 Kts X-wind limit if the runway is longer than 2000m, and 30Kts X-wind limit if it is less than 2000m,
Right so far!

Originally Posted by old,not bold
ie shorter runway, higher limit.
31st May 2019, 16:47

Join Date: Apr 2006
Location: uk
Posts: 743
Test is booked at the nearest clinic; I don't know what brought on that brainf**t!
1st Jun 2019, 02:47

Join Date: Feb 2019
Location: shiny side up
Posts: 385
The good news is, that after review of the MAX, and relating down to the NG procedures...

Crosswind takeoffs will no longer be allowed.

Problem solved.
1st Jun 2019, 10:47

Join Date: Apr 2012
Location: In Space
Posts: 603
Originally Posted by t-bag
Oh FFS - you clearly have never flown a commercial airplane...........
I totally agree!
Firstly, Glasgow would vector you after a missed approach.
1st Jun 2019, 11:20

Join Date: Jun 2001
Location: FNQ ... Still!
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Is it April 1st again?

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