Max Cross-wind component B.737-800
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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.
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.
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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.
Graham McFadyen
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.
Graham McFadyen
Join Date: May 2019
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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.
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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.
Graham McFadyen
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.
Graham McFadyen
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-
‘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-
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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.
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.
For our company: B738 with or without winglets on wet runway = 34kts (TORA/LDA >2.000m) and 30kts (TORA/LDA< 2.000m)
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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?
Just thinking out loud...
= 34kts (TORA/LDA >2.000m) and 30kts (TORA/LDA< 2.000m)
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.
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