MAX crosswind for a B737

[CO757flyer]

Winds are 270 at 35 gusting to 50 and the runway is 36. Just checking but the gust is the controlling number for takeoff or am i dreaming that up.

[Northbeach]

From my “limitations” section:

Maximum Dry runway Wind Limits Takeoff and Landings:
Maximum Steady State Wind Velocity…………….. 50 kts.
Maximum Gust Velocity……………………………. 20 kts.

Maximum Crosswind
Flight Crews shall comply with the crosswind guidelines contained in the Environmental Procedures section.

Crosswind Takeoff & Takeoff Crosswind Limits


Braking Action ////Max Crosswind 737-400 /// NG without / with winglets

Dry 40 36 / 34
Good 25 25
Medium 16 15
Poor 10 10

Crosswind considerations.

1. For dispatch, use steady state wind velocity for crosswind computations.
2. Guest velocities are advisory, however, operations with a steady state component near the crosswind limits with higher gusts should be considered unacceptable.
3. The Captain may choose to further reduce these limits based on such factors as MELs, guest velocity, runway width/length, braking action, weather, pilot currency and aircraft experience.


In summary; the amount of crosswind you can accept on a runway for takeoff (and landing) varies, starting with the braking action (traction ability) of the departing runway.

A 90 degree, direct crosswind, at 35 knots on a bone dry brand new long runway technically works for a -400 and NG without winglets, but not for a NG with winglets (34 knot limit).

Just checking but the gust is the controlling number for takeoff or am i dreaming that up.

You have a 15 knot gust, the upper "limit" is 20 knots, so your 15 knot gust example is below the limitation. If by "controlling" I understand you to mean limiting-beyond which is not approved operations, then no the 15 knot gust is not controlling. However, the "company/airline" may have stricter, more limiting, numbers. In such a case then yes the 15 knots would be controlling/limiting. The pilot may for whatever reason have a lower guest limit as well, and that would be controlling/limiting.

If you were flying a NG with winglets your 90 degree crosswind at 35 knots gusting to 50, would be one knot beyond your dry runway limit of 34 knots. "For dispatch, use steady state wind velocity for crosswind computations" (from the environmental section of my manual).

Are you a pilot flying these machines, or any other aircraft, or a flight simmer?

http://farm4.static.flickr.com/3107/3161227813_e6d9a55c5f.jpg

[Denti]

737-400 NG
Are you a pilot flying these machines, or any other aircraft, or a flight simmer?

Indeed, considering the first quote, that is a very valid question...

However, the answer is found in Aircraft Limitations. We just got a complete revision of the wind section, now there is a difference between take off and landing whereas before both were identical. All wind limits now include gusts, so the highest windspeed reported is limiting. However that is a company tailored manual so differences to a standard boeing FCOM are possible.

Crosswind limits for takeoff (B737-700/800):

Dry (with winglets) 34 kts
Dry (without winglets) 36 kts
Wet: 25 kts
Standing Water / Slush: 15 kts
Snow - No Melting: 25 kts
Ice - No Melting 15 kts

Crosswind Limits for landing:

Dry: 40 kts
Wet: 40 kts
Standing Water /Slush 20 kts
Snow - no melting: 35 kts
Ice - no melting: 17 kts.

Crosswind Limits for autoland: 25 kts.
Crosswind Limits for autoland (One Engine Inoperative): 20 kts.

Crosswind limit have to be reduced by 5 kts whenever assymetrical thrust is used, sideslip only (no crab) landings are not recommended with crosswind components greater than 17 kts at F15, 20 kts at F30 or 23 kts at F40. Take off and landing on untreated snow or ice is only allowed if no melting is present.

All limits are valid for both narrow runway operation and runways with a width of 45m or more.

[PEI_3721]

Crosswind Certification - How does it affect you? (http://www.nlr.nl/id%7E5114/lang%7Een.pdf)

Quote from para 5
Most operators use crosswind limits that do not exceed the demonstrated crosswinds,
Most of the operators include gusts in their crosswind limits,
All operators adjust the crosswind limits for wet and contaminated runways,
Some of the operators adjust the crosswind limits for visibility,
Most of the operators have reduced crosswind limits for less experienced pilots.
Most operators account for runway width.

And then what about stopping distance? If asymmetric bake is used to aid steering, then this reduces the brake effectiveness for stopping; this might be more noticeable during gusts.

SKYbrary - Cross Wind Landings (http://www.skybrary.aero/index.php/Cross_Wind_Landings)
http://www.skybrary.aero/bookshelf/books/871.pdf

SKYbrary - Wind Velocity Reporting (http://www.skybrary.aero/index.php/Wind_Velocity_Reporting)
http://www.skybrary.aero/bookshelf/books/870.pdf

[piratepete]

The whole issue of crosswind "conditions" for MANUAL take off and landing operations is interesting.Long ago there was a reference in the Boeing manuals for the types that im currently flying in the LIMITATIONS section of the FCOM.However at some stage these Limitations disappeared and were replaced by TAKEOFF and LANDING GUIDELINES, TALPA ARC and non-TALPA ARC.In other words there are no longer hard and fast LIMITATIONS as such but simply GUIDELINES.It is of course entirely up to individual airlines and/or their Regulator to impose Limitations as long as they are equal to or more restrictive than the said GUIDELINES.The issue of GUSTS are not mentioned or even addressed, however it would be good airmanship and common sense to do so.For AUTOLAND operations there are stated LIMITATIONS as has been the case for a long time.Peter.