komododx
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Max Cross-wind For Landing

Fri Apr 01, 2005 6:46 am

I was just watching the weather channel (15:44 EST) and Stephanie Abrahams was mentioning strong winds in the Chicago area. She then tried to explain what a cross-wind is and said "when there are cross-winds, airplanes can't land." Wow! I am surprised that she being a meteorologist wouldn't know that planes do land in cross-winds.

My question is, for an airport with one rwy (or two parallel) what would be the max cross-wind allowed for landing before they make them divert?

Stefano
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chrisjake
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RE: Max Cross-wind For Landing

Fri Apr 01, 2005 6:49 am

isn't the crosswind component dependent on the type of aircraft?


chris
 
jtamu97
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RE: Max Cross-wind For Landing

Fri Apr 01, 2005 7:45 am

Yes that is true plus it depends on the angle of a the crosswind and if the surface is wet or dry as well. A 10 degree, 50 degree, etc. and from looking around it looks like anywhere from 20kts to 35 kts is the maximum component for a 90 degree angle crosswind.

[Edited 2005-03-31 23:47:09]
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aerlingus330
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RE: Max Cross-wind For Landing

Fri Apr 01, 2005 7:59 am

I was watching Air Crash investigation yesterday about a plane that was in Bad weather. When the airplane got closer to the landing runway, the visibility and crosswinds went below regulations. The pilots were so occupied by tackling the crosswind, they forgot to arm the spoilers. Because of this the plane didn't stop on the runway in time and skidded of into a ditch, killing the captain and a few passengers.
Anyway, the court case reveled a scandal in American Airlines. American Airlines didn't give pilots enough information about regulations in crosswinds. However, American Airlines was not entirely to blame. The pilots were on their last flight of the day and jeopardized the lives of the passengers by not aborting the landing or diverting. As a consequence, they forgot to arm the spoilers and people died.

AerLingus330
Aer Lingus Airbus A330-300
 
DLKAPA
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RE: Max Cross-wind For Landing

Fri Apr 01, 2005 8:01 am

Quoting Jtamu97 (Reply 2):
and from looking around it looks like anywhere from 20kts to 35 kts is the maximum component for a 90 degree angle crosswind.

I watched a Dash 8 land yesterday in 22kt constant with gusting to 35Kts in an almost direct crosswind. The sock was starched.
And all at once the crowd begins to sing: Sometimes the hardest thing and the right thing are the same
 
TedTAce
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RE: Max Cross-wind For Landing

Fri Apr 01, 2005 8:21 am

One of my few really good memories in flight training was the one day I convinced the chief flight instructor it was safe to take a 152 up because while the winds were at 15-20 Kts, the crosswind component was under 13 Kts. I was flying while other students were stuck on the ground 'cause they couldn't prove their case. It was beautiful  box 
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skibum9
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RE: Max Cross-wind For Landing

Fri Apr 01, 2005 8:33 am

Quoting Chrisjake (Reply 1):
isn't the crosswind component dependent on the type of aircraft?

Yes, you are correct. An airplanes ability to handle a crosswind is a component of the airplane itself. Every airplane is "rated" to handle a different crosswind component. This is dependent on the design on the plane and the point where a full deflection of the control surfaces cannot couteract the forces of the crosswind. Having said that, some operators will also put in place operating procedures that are below the maximum crosswind component on a specific airplane to add in a safety margin.
Tailwinds!!!
 
theunclesam
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RE: Max Cross-wind For Landing

Fri Apr 01, 2005 8:44 am

Those high wing aircraft don't like the crosswinds. Isn't Max. demonstrated crosswind for a 152 15kts? I may be incorrect. I think on a Warrior it is like 20kts. A low wing aircraft usually isn't affect by crosswinds as much as a high wing.
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OPNLguy
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RE: Max Cross-wind For Landing

Fri Apr 01, 2005 8:57 am

Quoting Komododx (Thread starter):
My question is, for an airport with one rwy (or two parallel) what would be the max cross-wind allowed for landing before they make them divert?

The number of runways, and whether they are parallel or not really isn't a factor, per se. There isn't a -single- value for max crosswind component, as it depends (as usual) upon a number of other factors.

For instance, assuming a dry runway, the limit might be 30 kts. If the runway is wet, the max could be 15 kts. If the weather is < 3/4 mile visibility or < RVR4000, the limit is 10 kts. If the runway has clutter and has degraded braking action, the max crosswind limit could be as low as 5 kts.

Moral of the story: take anything that a TV person says with a rather generously-sized grain of salt...  Wink
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
komododx
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RE: Max Cross-wind For Landing

Fri Apr 01, 2005 9:39 am

Quoting OPNLguy (Reply 8):
The number of runways, and whether they are parallel or not really isn't a factor, per se

If they have cross rwys a la SFO couldn't they just change active rwys?

That's what I meant.

Thanks for the reply, though!

It was funny to see the weather girl explaining a x-wind with her hands and how a/c can't land when there is any x-wind. She then talked about turbulence and how she gets "queasy" when it occurs  rotfl 

Stefano
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OPNLguy
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RE: Max Cross-wind For Landing

Fri Apr 01, 2005 9:48 am

Quoting Komododx (Reply 9):
Quoting OPNLguy (Reply 8):
The number of runways, and whether they are parallel or not really isn't a factor, per se

If they have cross rwys a la SFO couldn't they just change active rwys?

That's what I meant.

OK, that makes sense. The only runway relevant to the crosswind comptations is the one you intend to land on; that's the point I was going after. If an airport has other runways whose use results in a more acceptable crosswind component, so much the better, assuming that runway is open, has suitable navaids (if needed), etc.

What's -really- a bummer is when you have an airport with a runway layout and winds such that you're out of crosswind limits on different runways at the same time. For example, runways 12-30 and 04-22 with a wind of 18030 and you've got a 10-kt limit for some reason. Those winds put you out of limits for either runway.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
Celticmanx
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RE: Max Cross-wind For Landing

Fri Apr 01, 2005 11:00 am

The maximum Crosswind component that you ussually find on the Airplane flight Manual for any type of aircraft is a demonstrated max crosswind component. In other words, the test pilots from the manufacturer fly the airplane in different wind angles and speeds and found out that the max X-wind component they safely could managed in normal conditions (dry paved runway) with a new airplane fully operative was the one indicated in the Manual. However this does not mean a pilot is limited by that number it actually gives you a reference of the maximum x-wind manageable for the test pilots. You could still continue your approach and try to land with a stronger wind than that but remember that only then you automatically become a test pilot and if ever get caught in an incident, the insurance companies will have a good reason not pay you.
 
skibum9
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RE: Max Cross-wind For Landing

Fri Apr 01, 2005 12:12 pm

Quoting Celticmanx (Reply 11):
insurance companies will have a good reason not pay you

And insurance companies always look for a way NOT to pay!!!
Tailwinds!!!
 
stealthpilot
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RE: Max Cross-wind For Landing

Fri Apr 01, 2005 12:55 pm

Nope Theunclesam you are correct, the cross wind component for the C172 is 15 knots  Smile For the Seminole it’s 17 knots.
I believe for the bigger commercial planes the maximum cross wind component is a little over 30 knots in normal conditions. When using an autopilot or another system to bring the AC in, they have different level of XW they can handle as well.
-Nikhil
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CX Flyboy
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RE: Max Cross-wind For Landing

Fri Apr 01, 2005 10:06 pm

CelticManx is absolutely correct. Most airliners are rated to "Demonstrated Maximum Crosswind" meaning that it is not a strict limit. Line pilots can go beyond this if they wish, but must have a good explanation if anything goes wrong. The 777 has a limit of 38kts where I am, but I don't think the company would argue if you landed in a steady 40kt crosswind.

Some companies may set a firm, hard limit for the pilots, in which case crew cannot break the limit, but others stick to the manufacturer's guidelines of a 'max demonstrated crosswind" only.
 
PhilSquares
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RE: Max Cross-wind For Landing

Fri Apr 01, 2005 10:37 pm

Quoting CX flyboy (Reply 14):
I don't think the company would argue if you landed in a steady 40kt crosswind.

I certainly wouldn't want to land beyond the demonstrated limit and scrape a wing or a pod. I can guarantee you the airline would say something. Me personally, I wouldn't try in a million years. I don't have to get someplace that bad.
Fly fast, live slow
 
CX Flyboy
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RE: Max Cross-wind For Landing

Fri Apr 01, 2005 10:56 pm

Phil,

Well, it's hard to make any firm statement on an internet forum about what to do in real situations. Let's say in a 744, steady at 25kts, gusting 32. I believe most crew would give it a go.

[Edited 2005-04-01 15:04:51]
 
PhilSquares
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RE: Max Cross-wind For Landing

Fri Apr 01, 2005 11:15 pm

CX flyboy
No, it's very easy in that example. There is no problem at all since the gust is not considered in the crosswind calculation. However, if the wind was a steady state at 31 knots, I'm off to my alternate. Our ops policy has a limit of 30knots manual landing and 25 knots crosswing (dry runway). To me, it's pretty cut and dry.
Fly fast, live slow
 
TedTAce
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RE: Max Cross-wind For Landing

Fri Apr 01, 2005 11:53 pm

Quoting Theunclesam (Reply 7):
Those high wing aircraft don't like the crosswinds. Isn't Max. Demonstrated crosswind for a 152 15kts? I may be incorrect. I think on a Warrior it is like 20kts. A low wing aircraft usually isn't affect by crosswinds as much as a high wing.

I want to say that you might be right. I think it also depends on what year the 152 was made, I'm sure someone will say the Aerobat had a "17Kt" X-wind or something like that.

One thing I want to point out that hasn't apparently been mentioned by other posters is the function of cross wind component.

Obviously if you have a plane on runway 09 (E), and winds are out of 090 (E), there is no crosswind. If the winds are out of 360(N) or 180(S), what ever the winds are, is the cross wind. The thing to keep in mind that neither of those two situations occur with any level of consistency (I would say never, but I would only be speaking for myself) so you have to factor the angle of the wind to the runway.

Now I have long since packed away my E-6 so please don't think the #'s I'm using in the following example are even CLOSE to real.

Say you have your A/C on 09 (East) and the winds are out of 120 (ESE) @ 15Kts. Well your crosswind isn't 0, and it certainly isn't 15 is it? Probably something like 5kts. If the winds were out of 160 (SSE) it might be around 10kts.

The thing to keep in mind is while in all likely hood you can violate these values, the second you do, you become a test pilot. You are endangering yourself, your pax (if any) and (most importantly to me if you don't have pax) your equipment. If you think you want to roll the dice, please make another decision, get down safley and sign the plane over to me, I'll be happy to fly it  Smile
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CX Flyboy
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RE: Max Cross-wind For Landing

Sat Apr 02, 2005 12:33 am

PhilSquares,

I guess thats where every airline differs in terms of how they interpret the manufacturer flight manuals and how they guide, or instruct their pilots in what to do. Training philisophy varies from airline to airline as you know.

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