The altitude at which a plane flies depends on the type of aircraft, its intended use, and a number of other factors:

Commercial airliners: Typically fly at altitudes between 30,000 and 42,000 feet, with a maximum safe altitude of around 43,100 feet.

Private jets: Can fly at altitudes above 45,000 feet.

Fighter jets: Typically fly at altitudes between 45,000 and 51,000 feet. Advanced military fighter jets like the F22 Raptor, F35 Lightning, or the Eurofighter Typhoon can reach altitudes of between 50,000–65,000 ft.

Smaller aircraft: Usually fly at lower altitudes, often below 15,000 feet.

The higher a plane flies, the thinner the air becomes, which produces less lift for the aircraft. This makes it less efficient to fly.

Planes fly high to avoid bad weather, which is most likely in the troposphere, the atmospheric layer closest to the ground. They also prefer the stratosphere, which has less turbulence.

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