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This question already has an answer here:

I was wondering if it would be better to take off into the wind because then you would need less overall acceleration to takeoff, or with the wind behind you - thereby making it easier for the plane to fly when it's in the air?

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marked as duplicate by J. Hougaard, SMS von der Tann, ymb1, Ralph J, fooot Sep 26 '17 at 18:50

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    $\begingroup$ thereby making it easier for the plane to fly when it's in the air -- How? Tailwind decreases the climb gradient and decreases the climb weight for the same obstacle clearance. $\endgroup$ – ymb1 Sep 26 '17 at 17:53
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Almost always into the wind. The ground roll will be substantially decreased because you've already got a certain amount of airflow over the wings.

Taking off with a tailwind is pretty much never advisable unless it's a one-way strip or runway, or the winds are below the tailwind limitations for that aircraft type.

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  • $\begingroup$ you could add that a good reason for using a runway one way only is runway slope. $\endgroup$ – Peter Kämpf Sep 26 '17 at 17:59
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The speeds required for planes to fly are speeds relative to the air, not relative to the ground. You are correct that taking off with the wind will require less acceleration to get to a certain speed, but that speed is relative to the ground, so you might not be at the required air speed.

Picture a runway left to right. A plane on the right side wants to take off to the left, and a wind is blowing. Consider two cases:

  1. The wind is blowing left to right(headwind). Any rightward wind speed can be added to the plane's leftward ground speed. If the plane can take off at, say, 50 kts, if the wind is 10 kts, the plane's required ground speed is only 40 kts. The total airspeed is 50kts.
  2. The wind is blowing right to left(tailwind) Any leftward wind speed must be subtracted from the plane's ground speed to get airspeed. Again, trying to reach an airspeed of 50kts, a tailwind of 10 kts will require a faster ground speed. The aircraft's speed relative to the ground will be 60kts before it can take off, though the instrument airspeed will only measure 50 kts.

So, for those cases, there is a difference of 20 kts ground speed. It can take a bit more runway to get to 50 kts airspeed if your ground speed is even faster than that. Most pilots don't enjoy running out of runway.

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