170.15 ATCT Discontinuance Criteria. This subpart sets forth establishment and discontinuance criteria for navigation aids operated and maintained by the United States. Air traffic clearance means an authorization by air traffic control for an aircraft to proceed under specified traffic conditions within controlled airspace for the purpose of preventing collision between known aircraft. Air traffic controller means a person authorized to provide air traffic service, specifically en route and terminal control personnel. Aircraft operations means the airborne movement of aircraft in controlled or noncontrolled airport terminal areas, and counts at en route fixes or other points where counts can be made.
Itinerant operations mean all aircraft operations other than local operations.
Alternate airport means an airport, specified on a flight plan, to which a flight may proceed when a landing at the point of first intended landing becomes inadvisable. Approach means the flightpath established by the FAA to be used by aircraft landing on a runway. Approach control facility means a terminal air traffic control facility providing approach control service. Arrival means any aircraft arriving at an airport. Criteria means the standards used by the FAA for the determination of establishment or discontinuance of a service or facility at an airport.