14 CFR § 170.3 - Definitions.
For purposes of this subpart -
Air 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.
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.
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. There are two types of operations: local and itinerant.
(1) Local operations mean operations performed by aircraft which:
(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
Airport 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.
Ceiling 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.”
Control Tower - See Airport Traffic Control Tower.
Discontinuance means the withdrawal of a service and/or facility from an airport.
Establishment means the provision of a service or facility at a candidate airport.
Instrument 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.
Instrument 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.
Instrument meteorological conditions (IMC) means weather conditions below the minimums prescribed for flight under Visual Flight Rules (VFR).
Instrument 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).
Life cycle benefits means the value of services provided to aviation users over the life span of a facility or service.
Life 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.
Maintenance costs means the costs incurred in servicing and maintaining a facility after establishment.
Mean sea level (MSL) means the base commonly used in measuring altitudes.
Noncommercial traffic means all aircraft operations that are conducted free of compensation.
Nonscheduled 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.
Present value (PV) means the value of a stream of future benefits or costs that are discounted to the present.
PVB or BPV means the discounted value of life cycle benefits.
PVC or CPV means the discounted value of life cycle benefits.
PVCM or CMPV means the discounted value of operations and maintenance costs less termination costs over a facility's remaining life cycle.
Separation means the spacing of aircraft in flight and while landing and taking off to achieve their safe and orderly movement.
Traffic 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.
Visual 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.
Visual meteorological conditions (VMC) means meteorological conditions expressed in terms of visibility, distance from clouds, and ceiling equal to or better than specified minima.