How high do planes fly?

That's well above almost all weather, which is one of the main reasons planes climb that high in the first place. Storms, cloud and turbulence are mostly a lower-atmosphere problem.

The air up there is also much thinner, which sounds like a disadvantage until you remember engines have to push through it. Thinner air means less drag on the airframe, so the aircraft burns less fuel to cover the same distance — cruising altitude is really a trade-off between thin, efficient air and an engine's ability to still generate enough thrust and lift in it. Smaller propeller aircraft, without the same engines or a pressurised cabin, typically stay much lower.

It's also why the sky at that altitude looks the deep, flat blue you get in a good aircraft print — there's simply less atmosphere left to scatter the light. If you've ever wondered about the bumps on the way up, we cover that in what turbulence actually is.

Written by Craig Fearn, Aviation Gift Co.