{"data":{"id":"us/14-cfr-170.3","jurisdiction":"us","citation":"14 CFR 170.3","heading":"Definitions.","body":"For purposes of this subpart—\nAir navigation facility (NAVAID) means any facility used, available for use, or designated for use in the aid of air navigation. Included are landing areas; lights; signaling, radio direction-finding, or radio or other electronic communication; and any other structure or mechanism having a similar purpose of guiding or controlling flight or the landing or takeoff of aircraft.\nAir 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.\nAir traffic control (ATC) means a service that promotes the safe, orderly, and expeditious flow of air traffic, including airport, approach, departure, and en route air traffic control.\nAir traffic controller means a person authorized to provide air traffic service, specifically en route and terminal control personnel.\nAircraft 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. There are two types of operations: local and itinerant.\n(1) Local operations mean operations performed by aircraft which:\n(i) Operate in the local traffic pattern or within sight of the airport;\n(ii) Are known to be departing for, or arriving from flight in local practice areas located within a 20-mile radius of the airport; or\n(iii) Execute simulated instrument approaches or low passes at the airport.\n(2) Itinerant operations mean all aircraft operations other than local operations.\nAirport traffic control tower means a terminal facility, which through the use of air/ground communications, visual signaling, and other devices, provides ATC services to airborne aircraft operating in the vicinity of an airport and to aircraft operating on the airport area.\nAlternate 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.\nApproach means the flight path established by the FAA to be used by aircraft landing on a runway.\nApproach control facility means a terminal air traffic control facility providing approach control service.\nArrival means any aircraft arriving at an airport.\nBenefit-cost ratio means the quotient of the discounted life cycle benefits of an air traffic control service or navigation aid facility (i.e., ATCT) divided by the discounted life cycle costs.\nCeiling means the vertical distance between the ground or water and the lowest layer of clouds or obscuring phenomena that is reported as “broken,” “overcast,” or “obstruction.”\nControl Tower—See Airport Traffic Control Tower.\nCriteria means the standards used by the FAA for the determination of establishment or discontinuance of a service or facility at an airport.\nDeparture means any aircraft taking off from an airport.\nDiscontinuance means the withdrawal of a service and/or facility from an airport.\nEstablishment means the provision of a service or facility at a candidate airport.\nInstrument approach means a series of predetermined maneuvers for the orderly transfer of an aircraft under instrument flight conditions from the beginning of the initial approach to a landing, or to a point from which a landing may be made visually. It is prescribed and approved for a specific airport by competent authority.\nInstrument flight rules (IFR) means rules governing the procedures for conducting flight under instrument meteorological conditions (IMC) instrument flight.\nInstrument landing system (ILS) means an instrument landing system whereby the pilot guides his approach to a runway solely by reference to instruments in the cockpit. In some instances, the signals received from the ground can be fed into the automatic pilot for automatically controlled approaches.\nInstrument meteorological conditions (IMC) means weather conditions below the minimums prescribed for flight under Visual Flight Rules (VFR).\nInstrument operation means an aircraft operation in accordance with an IFT flight plan or an operation where IFR separation between aircraft is provided by a terminal control facility or air route traffic control center (ARTCC).\nLife cycle benefits means the value of services provided to aviation users over the life span of a facility or service.\nLife cycle costs means the value of research and development costs, investment costs, operation costs, maintenance costs, and termination costs over the life span of a facility or service.\nMaintenance costs means the costs incurred in servicing and maintaining a facility after establishment.\nMean sea level (MSL) means the base commonly used in measuring altitudes.\nMicrowave landing system (MLS) means a landing system which enables equipped aircraft to make curved and closely spaced approaches to properly instrumented airports.\nNoncommercial traffic means all aircraft operations that are conducted free of compensation.\nNonprecision approach procedure means an FAA standard for approaching an IFR runway where no electronic glide slope is available.\nNonscheduled commercial service means the carriage by aircraft in air commerce of persons or property for compensation or hire that are not operated in regularly scheduled service such as charter flights.\nPresent value (PV) means the value of a stream of future benefits or costs that are discounted to the present.\nPVB or BPV means the discounted value of life cycle benefits.\nPVC or CPV means the discounted value of life cycle benefits.\nPVCM or CMPV means the discounted value of operations and maintenance costs less termination costs over a facility's remaining life cycle.\nRunway means a defined rectangular area on a land airport prepared for the landing and takeoff of aircraft along its length.\nRunway visual range means an instrumentally derived value based on standard calibrations that represent the horizontal distance a pilot will see down the runway from the approach end.\nScheduled commercial service means the carriage by aircraft in air commerce under parts 121 and 135 of persons or property for compensation or hire based on published flight schedules.\nSeparation means the spacing of aircraft in flight and while landing and taking off to achieve their safe and orderly movement.\nTakeoff clearance means authorization by an airport traffic control tower for an aircraft to take off.\nTower cab means an ATC facility located at an airport. Controllers at these facilities direct ground traffic, takeoffs, and landings.\nTraffic advisories means advisories issued to alert pilots to other known or observed air traffic which may be in such proximity to the position or intended route of flight of their aircraft to warrant attention.\nTraffic pattern means the flow of aircraft operating on and in the vicinity of an airport during specified wind conditions as established by appropriate authority.\nVFR traffic means aircraft operated solely in accordance with Visual Flight Rules.\nVisual flight rules (VFR) means rules that govern the procedures for conducting flight under visual conditions. The term “VFR” is also used in the United States to indicate weather conditions that are equal to or greater than minimum VFR requirements. In addition, “VFR” is used by pilots and controllers to indicate the type of flight plan.\nVisual meteorological conditions (VMC) means meteorological conditions expressed in terms of visibility, distance from clouds, and ceiling equal to or better than specified minima.","path":["Title 14—Aeronautics and Space","CHAPTER I—FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION","SUBCHAPTER J—NAVIGATIONAL FACILITIES","PART 170—ESTABLISHMENT AND DISCONTINUANCE CRITERIA FOR AIR TRAFFIC CONTROL SERVICES AND NAVIGATIONAL FACILITIES","Subpart A—General"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-14.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:24:20Z","sha256":"e851cebdbd1965d056865f86686e650f180559613fb54f2e9a32670e93191214","source_id":"us-cfr","stale":true,"prev":"us/14-cfr-170.1","next":"us/14-cfr-170.11"},"notice":"GroundRules: Original legal text. Not legal advice."}