14 CFR §187.3

For the purpose of this part: Great circle distance means the shortest distance between two points on the surface of the Earth. Overflight means a flight through U.S.-controlled airspace that does not include a landing in or takeoff from the United States. Overflight through Enroute airspace means an overflight through U.S.-controlled airspace where primarily radar-based air traffic services are provided. Overflight through Oceanic airspace means an overflight through U.S.-controlled airspace where primarily procedural air traffic services are provided. U.S.-controlled airspace means all airspace over the territory of the United States, extending 12 nautical miles from the coastline of U.S. territory; any airspace delegated to the United States for U.S. control by other countries or under a regional air navigation agreement; or any international airspace, or airspace of undetermined sovereignty, for which the United States has accepted responsibility for providing air traffic control services.