Photo: Rhett Allain. It’s just a plane flying.

Round Trip Flying Time with a Constant Wind

Rhett Allain
7 min readJul 28, 2023

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Here’s a fun physics question for you. It goes like this:

Suppose a plane can fly with a constant air speed from point A to B and back without any wind. If there is a constant wind, what happens to the round trip time? Does it stay the same, increase, or decrease? Another option: it depends on the wind speed.

Here’s a picture to go along with this.

It’s fun because everyone probably has an idea for an answer and you don’t really need to get out a calculator to justify your choice (but you are welcome to crunch some numbers also).

Are you ready for the answer? If so, I’m going to give you three versions: a conceptual answer, an algebraic answer, and a python-based answer. Let’s go.

Relative Velocity

We need to address one important point before getting to a solution. There’s a difference between a plane’s air speed and the ground speed. The air speed is the velocity of the plane with respect to the air. However, if the air is also moving (a thing we like to call “wind”) then the plane can have a different ground speed.

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Rhett Allain
Rhett Allain

Written by Rhett Allain

Physics faculty, science blogger of all things geek. Technical Consultant for CBS MacGyver and MythBusters. WIRED blogger.

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