If you planned out a flight route, you might assume that a straight line due west across the Pacific Ocean would be the quickest route. After all, the shortest distance between two points is a straight line, right?
While that's true, your route due west over the Pacific wouldn't be the most efficient. In reality, airplanes making the trip from Los Angeles to Asia would travel in an arc that would take them past parts of Alaska and Russia.
What's up with that? Why don't planes fly in a straight line? It probably has something to do with all that wind way up high in the sky, right? Or could it be because pilots can't see the ground to steer in a straight line? Maybe it has something to do with gravity pulling on the plane as it travels?
While gravity does still maintain a bit of pull on an airplane in flight, it doesn't keep it from flying in a straight line. Pilots aren't to blame either, as they do a good job of "seeing" with their machines, even in brisk winds.
The flight paths of airplanes seem strange when we see them on a flat map for a couple of reasons. Contrary to what explorers believed hundreds of years ago, Earth is not flat. Instead, it's a sphere that's slightly flattened at the poles. When traditional flat maps are made, distortions occur when the sphere is made flat.
Those flight paths that don't appear straight on a flat map will look quite straight if you look at them on a globe. To test it for yourself, use a string to connect two cities halfway across the world. You'll see that the flight path, as represented by the string, is not what you would expect it to be if you were looking at a flat map.
Instead of relying on flat maps, airplanes follow "great circle" routes that account for the curvature of the Earth. What looks like a long detour on a flat map actually turns out to be the shortest route across the globe through the air.
The next time you think about traveling from one place to another via air, don't forget to think in three dimensions! Just follow the curve of the Earth and you'll get there in no time!