I hope this is helpful:
The atmosphere is divided into; the troposphere (approx. 36.000 feet, where most of the flying takes place), the stratosphere (approx. 164.000 feet), the Mesosphere (approx. 262.000 feet) and the ionosphere, which is divided into four layers and extends to about 700 kilometers. That´s approx. 2296700 Feet.
When you leave the ionosphere, you´re out of the atmosphere!
Muhammad Ali: "Superman don’t need no seat belt." Flight Attendant: "Superman don’t need no airplane, either."