How windy does it have to be for planes not to take off.
Feb 19, 2007, 7:09 pm
#16
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That is essentialy correct, but a tailwind's effect on takeoff distance is dramatic.
There are some runways, too, that are essentially one-way runways; most of these are, e.g., small airstrips in mountainous regions which, due to obstructions at one end, can only be used in one direction. If the wind is wrong, then no takeoff is possible (or prudent anyway!)
There are some runways, too, that are essentially one-way runways; most of these are, e.g., small airstrips in mountainous regions which, due to obstructions at one end, can only be used in one direction. If the wind is wrong, then no takeoff is possible (or prudent anyway!)
Feb 20, 2007, 7:25 am
#17
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DCA may or may not fit in your catagory as a major airport, but I think that when the rare 40 knot easterly or westerly comes in, a number of planes cannot use the field.
taking off in a 40 knot tail wind as opposed to a 40 knot headwind increases requireed ground speed by 80 knots between the two. lift off would be 40knots over dead calm.
I do not know anytihing about max tire speeds, but on a nice hot day in denver, that would put takeoff at wellover 200 mph. some of those tiny tires are going around verry verry fast.
taking off in a 40 knot tail wind as opposed to a 40 knot headwind increases requireed ground speed by 80 knots between the two. lift off would be 40knots over dead calm.
I do not know anytihing about max tire speeds, but on a nice hot day in denver, that would put takeoff at wellover 200 mph. some of those tiny tires are going around verry verry fast.
Feb 20, 2007, 9:58 am
#18
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In which direction?
Most of the time, cross-winds are the problem. cblaisd pretty much said it all. Usually, runways are designed, based on past wind data, to be open at least 95% of the time, due to crosswinds.
If you get heavy tailwinds and the runway is not long enough for a particular plane going to a particular place, then the plane won't take off. (the same is true for landings)
Not sure if there's a limit for headwinds, but I imagine there must be.
Most of the time, cross-winds are the problem. cblaisd pretty much said it all. Usually, runways are designed, based on past wind data, to be open at least 95% of the time, due to crosswinds.
If you get heavy tailwinds and the runway is not long enough for a particular plane going to a particular place, then the plane won't take off. (the same is true for landings)
Not sure if there's a limit for headwinds, but I imagine there must be.
That being said, I think an average of 20kts is acceptable, but it varies on the aircraft type.
The AF crash in Toronto was in part due to the 35nm+ winds (and part in pilots error and bad decision making).
Feb 20, 2007, 10:36 am
#19
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All transport category aircraft with which I'm familair have a 10kt tailwind limit for takeoff and landing. Tailwind takeoffs and landings are not uncommon but weight penaltites must be applied and 10kts of tailwind is the limit.
Many airports have a preferred runway for noise abatement or operational reasons. They will continue to use the preferred runway, even with a tailwind, until the tailwind gets close enough to the limit that the tailwind will start to cause operational problems.
Many airports have a preferred runway for noise abatement or operational reasons. They will continue to use the preferred runway, even with a tailwind, until the tailwind gets close enough to the limit that the tailwind will start to cause operational problems.
Feb 20, 2007, 11:37 am
#20
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All transport category aircraft with which I'm familair have a 10kt tailwind limit for takeoff and landing. Tailwind takeoffs and landings are not uncommon but weight penaltites must be applied and 10kts of tailwind is the limit.
Many airports have a preferred runway for noise abatement or operational reasons. They will continue to use the preferred runway, even with a tailwind, until the tailwind gets close enough to the limit that the tailwind will start to cause operational problems.
Many airports have a preferred runway for noise abatement or operational reasons. They will continue to use the preferred runway, even with a tailwind, until the tailwind gets close enough to the limit that the tailwind will start to cause operational problems.
Feb 20, 2007, 12:17 pm
#21
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As a non-physicist (
), I'd have to agree that it would have something to do with the amount of force perpendicular to the aeroplane, but then I'd imagine that some sort of adjustment would have to be made with respect to certain characteristics of the aeroplane itself - size of the vertical stabilizer, etc - that would create varying changes in yaw based upon wind direction (or is it assumed that the pilot would compensate for any such changes?).
My question is more about the actual maximum crosswind component. I'm guessing it's merely a "this aeroplane can withstand an X kt crosswind" and then doing elementary trigonometry to determine the crosswind and headwind components of a wind given its speed and direction from the referenced sites. If not, I'm definately interested as to exactly what it is and how pilots can calculate the "effective" (for the lack of a better word) crosswind given a situation.
), I'd have to agree that it would have something to do with the amount of force perpendicular to the aeroplane, but then I'd imagine that some sort of adjustment would have to be made with respect to certain characteristics of the aeroplane itself - size of the vertical stabilizer, etc - that would create varying changes in yaw based upon wind direction (or is it assumed that the pilot would compensate for any such changes?).My question is more about the actual maximum crosswind component. I'm guessing it's merely a "this aeroplane can withstand an X kt crosswind" and then doing elementary trigonometry to determine the crosswind and headwind components of a wind given its speed and direction from the referenced sites. If not, I'm definately interested as to exactly what it is and how pilots can calculate the "effective" (for the lack of a better word) crosswind given a situation.
The airlines themselves I am sure have maximum crosswind numebrs past which they will not launch. But for airplanes, the wind speed itself is near meaningless, it's the CROSSWIND component. A 60 MPH wind down teh runway has no crosswind component. a 20 MPH wind blosing at a 90 degree angle to the airplane has a 20 MPH crosswind component. That is why so many airports have runways facin different directions, you always take off and land into the wind as directly as possible. If Ihave runways 5, 14, 23 and 32 and the wind is blosing out of the northeast (060 degrees) runway 5 (at 050 degrees) is the one that will be in use. Landing on runway 14 will give you a strong left to right crosswind.
--PP