Air space

portion of the atmosphere controlled by a country

Air space is the area of the air that is controlled by a country or organisation. You have to have the permission of the controller to enter their air space in an airplane.[1] The air traffic controllers make sure the planes go in the right place and do not hit each other or something else. Some countries are very protective of their air space.

References

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  1. A Dictionary of Aviation, David W. Wragg. ISBN 9780850451634, 1st Edition Published by Osprey, 1973 / Published by Frederick Fell, Inc., NY, 1974 (1st American Edition.), Page 29.