abandoned runway: A runway permanently closed to aircraft operations which may be marked in accordance with current FAA standards for marking and lighting of deceptive, closed, and hazardous area on airports.
access taxiway: A taxiway that provides access to a particular location or area. (FAA Order 1000.15A)
active aircraft: Aircraft registered with the FAA and reported or estimated to have been flown at least one hour during the preceding year.
actual runway length: The length of full-width usable runway from end to end of full strength pavement where those runways are paved. (FAA Order 1000.15A)
administrative building: A building or buildings accommodating airport administration activity and public facilities for itinerant and local flying, usually associated with general aviation fixed-based operations. (FAA Order 1000.15A)
Advisory Circular (AC): A series of external FAA publications consisting of all non-regulatory material of a policy, guidance, and informational nature. (FAA Order 1000.15A)
AGL: Above ground level. (FAA Order 1000.15A)
air carrier: A scheduled operator carrying passengers, mail, or cargo for revenue in accordance with FAR Part 121 or 127. (FAA Order 1000.15A)
aircraft: A device that is used or intended to be used for flight in the air. (FAR Part 1)
aircraft mix: The number of aircraft movements categorized by capacity group or operational group, and specified as a percentage of total aircraft movements. (FAA Order 1000.15A)
aircraft operations: The airborne movement of aircraft in controlled or noncontrolled airport terminal areas and about given en-route fixes or at other points where counts can be made. There are two types of operations-local and itinerant.
(1) Local operations are performed by aircraft which:
(a) Operate in the local traffic pattern or within sight of the airport.
(b) Are known to be departing for, or arriving from, flight in local practice areas within a 20-mile radius of the airport.
(c) Execute simulated instrument approaches or low passes at the airport.
(2) Itinerant operations are all aircraft operations other than local operations. (FAA Order 1000.15A)
aircraft tiedown: Positions on the ground surface that are available for securing aircraft.
(FAA Order 1000.15A)
airport capacity: The rate of aircraft movements on the runway/taxiway system which results in a given level of delay.
air navigation facility (NAVAID): Any facility used in, available for use in, or designed for use in aid of air navigation, including landing areas, lights, any apparatus or equipment for disseminating weather information, for signaling, for radio direction-finding, or for radio or other electronic communication, and any other structure or mechanism having a similar purpose for guiding and controlling flight in the air or the landing or takeoff of aircraft.
airport: An area of land or water that is used or intended to be used for the landing and takeoff of aircraft, and includes its buildings and facilities, if any. (FAR Part 1)
Airport and Airway Development Act Amendments of 1976: Extended the 1970 Act for five years and included a number of amendments including the types of airport development projects eligible for ADAP funding, increased the federal share for ADAP and PGP grants, and initiated a number of studies concerning the National Airport System Plan (NASP)
Airport and Airway Development Act of 1970: A federal aid to airports program administered by the FAA for the 10-year period ending in 1980. Over $4.1 billion was invested in the airport system during this period.
Airport and Airway Improvement Act of 1982: Re-established the operation of the Airport and Airway Trust Fund with a slightly revised schedule of user taxes.
Airport and Airway Revenue Act of 1970: Created an airport and airway trust fund to generate revenues for airport aid. Taxes included an 8 percent surcharge on domestic passenger fares, a $3 surcharge on international passenger tickets, a 7 cents surcharge on fuel, a 5 percent surcharge on airfreight waybills, and an annual registration fee of $25 on all civil aircraft.
airport beacon: A visual navigation aid displaying alternating white and green flashes to indicate a lighted airport or white flashes only for an unlighted airport. (FAA Order 1000.15A)
airport configuration: The relative layout of component parts of an airport such as the runway-taxiway-terminal arrangement. (FAA Order 1000.15A)
Airport Reference Code (ARC): Includes Aircraft Approach Category and Airplane Design Group (ADG). The aircraft approach category is a grouping of aircraft based on 1.3 times their stall speed in their landing configuration at their maximum certificated landing weight. The ADG is a grouping of airplanes based on wingspan.
airport director: Sometimes referred to as airport manager or supervisor, the person responsible for the overall day-to-day operation of the airport.
airport elevation: The highest point of an airport's usable runways measured in feet above mean sea level.
airport imaginary surfaces: Imaginary surfaces established at an airport for obstruction determination purposes and consisting of primary, approach-departure, horizontal, vertical, conical, and transitional surfaces. (FAA Order 1000.15A)
Airport Improvement Program (AIP): The Airport Improvement Program of the Airport and Airways Improvement Act of 1982 as amended by the Airport and Airway Safety and Capacity Expansion Act of 1987. Under this program, the FAA provides funding assistance for the planning, design and development of airports and airport facilities.
airport layout plan (ALP): A graphic presentation, to scale, of existing and proposed airport facilities, their location on the airport, and the pertinent clearance and dimensional information required to show conformance with applicable standards. To be eligible for AIP funding assistance, an airport must have an FAA-approved Airport Layout Plan. (FAA Order 1000.15A)
Airport Master Plan: Presents the planner's conception of the ultimate development of a specific airport. It presents the research and logic from which the plan was evolved and displays the plan in a graphic and written report. The ALP is part of this plan.
airport reference point (ARP): A point having equal relationship to all existing and proposed landing and take-off areas.
airport requirements: First phase of the airport master plan which specifies new or expanded facilities that will be needed during the planning period. This involves cataloging existing facilities and forecasting future traffic demand. The planner compares the capacity of existing facilities with future demand, identifying where demand will exceed capacity, and what new facilities will be necessary.
airport sponsor: A public agency or tax-supported organization such as an airport authority, that is authorized to own and operate the airport, to obtain property interests, to obtain funds, and to be legally, financially, and otherwise able to meet all applicable requirements of current laws and regulations. (FAA Order 1000.15A)
air route: Navigable airspace between two points which is identifiable. (FAA Order 1000.15A)
Air Route Traffic Control Center (ARTCC): A facility established to provide positive air traffic control service to aircraft operating on IFR flight plans within controlled airspace. Controls only traffic en-route between airports. (FAA Order 1000.15A)
airspace: Space in the air above the surface of the Earth, or a particular portion of such space, usually defined by the boundaries of an area on the surface projected upward. (FAA Order 1000.15A)
airside facilities: The airfield on which aircraft operations are carried out, including runways and taxiways.
airspace capacity: Includes the proximity of airports to one another, the relationship of runway alignments, and the nature of operations. (IFR or VFR) in the area.
air taxi: Scheduled and/or nonscheduled aircraft operations carrying passengers and/or cargo for compensation. The capacity of air taxi aircraft is limited by Part 135 of the Federal Aviation Regulations. (FAA Order 1000.15A)
air taxi aircraft: Aircraft operated by the holder of an Air Taxi Operating Certificate, which authorizes the carriage of passengers, mail or cargo for revenue in accordance with FAR Parts 135 and 121. (FAA Order 1000.15A)
air taxi operator: An operator providing either scheduled or unscheduled air taxi service or mail service (FAA Order 1000.15A), and operate by FAR Part 135 using small aircraft (under 35 seats or a maximum payload of less than 7,500 pounds) (FAA Order 1000.15A)
air traffic: Aircraft operating in the air or on an airport surface, exclusive of loading ramps and parking areas. (FAR Part 1)
air transportation: Interstate, overseas, or foreign air transportation, or the transportation, or the transportation of mail by aircraft. (FAR Part 1)
airway: A path through the navigable airspace designated by appropriate authority within which air traffic service is provided.
ALP: Airport Layout Plan (see airport master plan).
ALS: Approach Lighting System.
alternate airport: An airport at which an aircraft may land if a landing at the intended airport becomes inadvisable. (FAR Part 1)
approach and clear zone layout: A graphic presentation to scale of the imaginary surfaces defined in FAR Part 77.
approach area: The defined area the dimensions of which are measured horizontally beyond the threshold over which the landing and takeoff operations are made. (FAA Order 1000.15A)
Approach Lighting System (ALS): An airport lighting facility which provides visual guidance to landing aircraft by radiating light beams in a directional pattern by which the pilot aligns the aircraft with the extended centerline of the runway on his final approach and landing. (FAA Order 1000.15A)
approach path: A specific flight course laid out in the vicinity of an airport and designed to bring aircraft in to safe landings; usually delineated by suitable navigational aids. (FAA Order 1000.15A)
approach slope ratio: The ratio of horizontal to vertical distance indicating the degree of inclination of the approach surface. (FAA Order 1000.15A)
approach surface: An imaginary surface longitudinally centered on the extended centerline of the runway, beginning at the end of the primary surface and rising outward and upward to a specified height above the established airport elevation. (FAA Order 1000.15A)
apron: A defined area, on a land airport, intended to accommodate aircraft for purposes of loading or unloading passengers or cargo, refueling, parking, or maintenance. (FAA Order 1000.15A)
apron/ramp: An area designated for aircraft use, other than taxiways and runways. Example uses for an apron include loading and unloading, parking, maintenance, refueling, before take-off engine runup, and as a temporary traffic holding area.
approved instrument approach: An instrument approach approved for general use and publication by the FAA. It must meet design, accuracy, and equipment requirements set by the FAA, and is subject to periodic FAA flight checks.
ARP: Airport Reference Point.
ARTCC: Air Route Traffic Control Center.
ASDE: Airport Surface Detection Equipment.
ASR: Airport Surveillance Radar.
ATC: Air Traffic Control.
ATIS: Automated Terminal Information Service.
ATCT: Air Traffic Control Tower.
Automated Weather Observing System (AWOS): This equipment automatically gathers weather data from various locations on an airport and transmits the information directly to pilots by means of computer generated voice messages over a discrete frequency. (FAA Order 1000.15A)
Aviation Safety and Noise Abatement Act of 1979: Provides assistance to airport operators to prepare and carry out noise compatibility programs. Authorizes the FAA to help airport operators develop noise abatement programs and makes them eligible for grants under ADAP.
avigation easement: A grant of a property interest in land over which a right of unobstructed flight in the airspace is established. (FAA Order 1000.15A)
based aircraft: The total number of active general aviation aircraft which use or may be expected to use an airport as a "home base."
base leg: (See traffic pattern).
basic data table: Shown on the airport layout plan drawing, it includes the airport elevation, runway identification and gradient, percent of wind coverage by principal runway, ILS runway when designated, normal or mean maximum daily temperature of the hottest month, pavement strength of each runway, and plan for obstruction removal, relocation of facilities.
basic runway length: Runway length resulting when actual length is corrected to mean seal level, standard atmospheric, and no gradient conditions. (FAA Order 1000.15A)
basic transport airport (or runway): An airport (or runway) that accommodates turbojet-powered aircraft up to 60,000 pounds gross weight. (FAA Order 1000.15A)
Basic Utility - Stage I: This type of airport serves about 75 percent of the single-engine and small twin-engine airplanes used for personal and business purposes. Precision approach operations are not usually anticipated. This airport is designed to serve small airplanes with a wingspan not exceeding 9 feet.
Basic Utility - Stage II: This type of airport serves all the airplanes of Stage I, plus some small business and air taxi-type twin-engine airplanes. Precision approach operations are not usually anticipated. This airport is designed to serve small airplanes with wingspans not to exceed 79 feet.
budgets: The planned dollar amounts needed to operate and maintain the airport during a definite period of time such as a year. There are capital budgets for major capital expenditures (such as runway resurfacing) and operating budgets to meet daily expenses.
building area: An area on an airport to be used, considered, or intended to be used, for airport buildings or other airport facilities or rights-of-way, together with all airport buildings and facilities located thereon.
building restriction line: A line shown on the airport layout plan beyond which airport buildings must not be positioned in order to limit their proximity to aircraft movement areas.
busy-hour operations: The total number of aircraft operations expected to occur at an airport at its busiest hour, computed by averaging two adjacent busiest hours of a typically high activity day.
by-pass taxiway: A taxiway located adjacent to an area which accommodates moving or parked aircraft specifically designed to achieve efficient aircraft passing movements.. (FAA Order 1000.15A)
capacity: The ability of an airport to handle a given volume of traffic (demand). It is a limit that cannot be exceeded without incurring an operational penalty.
ceiling: The height above the earth's surface of the lowest layer of clouds or other phenomena which obscure vision.
CIP: Capital Improvement Plan.
Civil Aeronautics Board (CAB): Responsible for the economic regulation of the certificated air carriers during the period from 1940 to 1985.
civil airport user categories: As used by airport planners, refers to the four major types of airports: certificated air carrier, commuter, general aviation, and military.
closed airport: An airport temporarily closed to aircraft operations for maintenance, construction, or some other purpose while the operator is still in business. (FAA Order 1000.15A)
closed field marking: Panels placed in the center of the segmented circle, or in the center of the field, in the form of a cross which will signify that the field is closed to all traffic. (FAA Order 1000.15A)
closed runway marking: Panels placed on the ends of the runway and at regular intervals in the form of a cross, signifying that a runway is closed to all traffic. (FAA Order 1000.15A)
commercial service: Commercial service airports are public use airports which receive scheduled passenger service aircraft, and which annually enplane 2,500 or more passengers, but do not qualify for primary service classification. (FAA Order 1000.15A)
conical surface: A surface extending from the periphery of the horizontal surface outward and upward at a slope of 20 to 1 for the horizontal distances and the elevations above the airport elevation as prescribed by FAR Part 77. (FAA Order 1000.15A)
controlled airspace: Airspace within which some or all aircraft may be subject to air traffic control to promote safe and expeditious flow of air traffic. (FAA Order 1000.15A)
controlling obstruction: The highest obstruction relative to a prescribed plane within a specific area. (FAA Order 1000.15A)
criteria for inclusion in the NASP: The principal criteria are: 1) that the airport has (or is forecast to have within five years) at least 10 based aircraft (or engines); 2) that it be at least a 30-minute drive from the nearest existing or proposed airport currently in the NASP; and 3) that there is an eligible sponsor willing to undertake ownership and development of the airport.
crosswind: A wind blowing across the line of flight of an aircraft. (FAA Order 1000.15A)
crosswind component: A wind component that is at a right angle to the longitudinal axis of the runway or the flight path of the aircraft. (FAA Order 1000.15A)
crosswind leg: A flight path at right angles to the landing runway off its upwind leg. (FAA Order 1000.15A)
crosswind runway: A runway additional to the primary runway to provide for wind coverage not adequately provided by the primary runway. (FAA Order 1000.15A)
dBA: A-weighted sound pressure level.
decibel (dB): A unit of noise level representing a relative quantity. This reference value is a sound pressure of 20 micronewtons per square meter. (FAA Order 1000.15A)
decision height (DH): With respect to the operation of aircraft, means the height specified in M.S.L. above the highest runway elevations in the touchdown zone at which a missed approach shall be initiated if the required visual reference has not been established (during the ILS or PAR instrument approach, to either continue the approach or to execute a missed approach). (FAR Part 1)
Department of Transportation (DOT): Established in 1966 to promote coordination of existing federal programs and to act as a focal point for future research and development efforts in transportation.
depreciable investment: The annual cost of capital invested in plant and equipment.
directional marker: An airway marker located on the ground used to give visual direction to an aircraft; consists of an arrow indicating true North and arrows indicating names and states of the nearest town.
discrete address beacon system (DABS): A sophisticated air traffic control surveillance system capable of interrogating each airborne DABS transponder in an "all-call" mode or with a discrete address signal encoded for each specific aircraft operating in the system. The data acquired upon response from each transponder are then processed to provide range, azimuth, altitude, and identity of each aircraft in the system on an individual basis but in sequence on a programmed interrogating schedule. Since aircraft are addressed individually in DABS, the surveillance system automatically provides a natural vehicle for a data link between ground and aircraft which can be used for ATC control purposes including the proposed intermittent positive control (IPC) concepts (FAA Order 1000.15A)
displaced threshold: A threshold that is located at a point on the runway other than the beginning. (FAA Order 1000.15A)
Distance Measuring Equipment (DME): A navigation ground station capable of receiving interrogations from aircraft and transmitting signals which allow time, speed, and distance computations to be made. The station is usually sited with a VOR and at times an ILS.
downwind leg: A flight path in the traffic pattern parallel to the landing runway in the direction opposite to landing. It extends to the intersection of the base leg. (FAA Order 1000.15A)
effective perceived noise level (EPNL): Time-integrated perceived noise level calculated with adjustments for irregularities in the sound spectrum, such as that caused by discrete-frequency components (tone-correction) The unit of effective perceived noise level is the decibel, with identifying prefix for clarification, EPNdB. (FAA Order 1000.15A)
effective runway length: (a) Effective runway length for takeoff means the distance from the end of the runway at which the takeoff is started to the point at which the obstruction clearance plane associated with the other end of the runway intersects the runway center-line. (FAR Part 121.171b) (b) Effective runway length for landing means the distance from the point at which the obstruction clearance plane associated with the approach end of the runway intersects the centerline of the runway to the far end thereof. (FAR Part 121.171b) (FAA Order 1000.15A)
entrance taxiway: A taxiway that provides entrance for aircraft to the takeoff end of the runway.
executive aircraft operator: A corporation, company, or individual which operates owned or leased aircraft, flown by pilot(s) whose primary duties involve pilotage of aircraft, as a means of transportation or personnel or cargo in the conduct of company business. (FAA Order 1000.15A)
exit taxiway: A taxiway used as an exit from a runway to the apron or other aircraft operating area. (FAA Order 1000.15A)
enplaned passengers: The total number of revenue passengers boarding aircraft, including originating, stopover and transfer passengers, in scheduled and non-scheduled services. (FAA Order 1000.15A)
FAA: Federal Aviation Administration.
FAA high-density rule: Quotas imposed at selected airports based on estimated limits of the air traffic control (ATC) system and airport runway capacity.
FAR: Federal Aviation Regulation.
FAR Part 77: A definition of the protected airspace required for the safe navigation of aircraft. (FAA Order 1000.15A)
FAR Part 107, Airport Security: Prescribes security rules for airport operators serving certificated air carriers.
FAR Part 91: General operating and flight rules.
FAR Part 150, Airport-Land Use Compatibility Planning: Designed to assist airport operators in determining the extent and nature of the noise problem at a given airport.
FAR Part 121: Certification and operations; domestic, flag, and supplemental air carriers and commercial operators of large aircraft. (FAA Order 1000.15A)
Federal Airport Act of 1946: A federal aid to airports program administered by the CAA (later the FAA) to give the United States a comprehensive system of airports. Over $1.2 billion in airport development aid funds were disbursed by the Federal Government during its 24-year history.
FAR Part 135: Air Taxi Operators and Commercial Operators.
Federal Aviation Act of 1958: Created the Federal Aviation Agency (FAA) with an administrator responsible to the President. The law retained the CAB as an independent agency and transferred the safety-rule-making powers to the FAA along with the functions of the CAA and the Airways Modernization Board.
Federal Aviation Administration (FAA): Created by the act that established the Department of Transportation. Assumed all of the responsibilities of the former Federal Aviation Agency.
federal government-operated airports: Two commercial airports serving the District of Columbia and surrounding area which were once managed by the FAA. They are Washington National and Washington-Dulles International.
final approach area(s): Areas of defined dimensions protected for aircraft executing instrument approaches. (FAA Order 1000.15A)
final approach (IFR): The flight path of an aircraft which is inbound to the airport on an approved final instrument approach course, beginning at the final approach fix (AIM, Part 1) and extending to the airport or the point where circling for landing or missed approach is executed.
final approach (VFR): A flight path, in the traffic pattern, of a landing aircraft in the direction of landing along the extended runway centerline from the base leg to the runway (AIM, Part 1).
final controller: That controller providing final approach guidance utilizing radar equipment (AIM, Part 1).
fixed base operator: An individual or company located at an airport, and providing commercial general aviation services. (FAA Order 1000.15A)
flareout: That portion of a landing maneuver in which the rate of descent is reduced to lessen the impact of landing. (FAA Order 1000.15A)
flight advisory service: Advice and information provided by a facility to assist pilots in the safe conduct of flight and aircraft movement. (FAA Order 1000.15A)
flight plan: Specified information relating to the intended flight of an aircraft, which is filed orally or in writing with air traffic control. (FAR Part 1)
Flight Service Station (FSS): A central operations facility in the national flight advisory system utilizing data interchange facilities for the collection and dissemination of NOTAMS, weather, administrative date; and providing preflight and inflight advisory service, and other services to pilot, via air/ground communication facilities. (FAA Order 1000.15A)
flight time: The time from the moment the aircraft first moves under its own power for the purpose of flight until the moment it comes to rest at the next point of landing ("block-to-block" time). (FAR Part 1)
fuel flowage fees: Fees levied by the airport operator per gallon of aviation gasoline and jet fuel sold at the airport.
general aviation: That portion of civil aviation which encompasses all facets of aviation except air carriers holding a certificate of convenience and necessity from the Civil Aeronautics Board, and commercial operators of large aircraft. (FAA Order 1000.15A)
general aviation airports: Those airports with fewer than 2,500 annual enplaned passengers and those used exclusively by private and business aircraft not providing common-carrier passenger service.
general aviation itinerant operations: Takeoffs and landings of civil aircraft (exclusive of air carrier) operating on other than local flights. (FAA Order 1000.15A)
glideslope transmitter (GS): An ILS navigation facility in the terminal area electronic navigation system, providing vertical guidance for aircraft during approach and landing by radiating a directional pattern of VHF radio waves modulated by two signals which, when received with equal intensity, are displayed by compatible airborne equipment as an "on-path" indication. (FAA Order 1000.15A)
handoff: Passing of control of an aircraft from one controller to another, either within the same facility or interfacility. (FAA Order 1000.15A)
hangar: A building used to store one or more aircraft, and/or conduct aircraft maintenance.
heliport: An area of land, water, or structure used or intended to be used for the landing and takeoff of helicopters. (FAR Part 1)
high-intensity light: A runway or threshold light whose main beam provides a minimum intensity of 12,000 candlepower in white light through a vertical angle of 3 degrees and a horizontal angle of 6 degrees.
HIRL: High intensity runway lighting. (FAA Order 1000.15A)
holding areas: Run-up areas located at or very near the ends of runways for pilots to make final checks and await final clearance for takeoff.
holding bay: An area where aircraft can be held, or bypassed, to facilitate efficient ground traffic movement. (FAA Order 1000.15A)
horizontal surface: A specified portion of a horizontal plane located 150 feet above the established airport elevation which establishes the height above which an object is determined to be an obstruction to air navigation. (FAA Order 1000.15A)
IFR: Instrument Flight Rules (FAR Part 91).
IFR airport: An airport with an authorized instrument approach procedure. (FAA Order 1000.15A)
IFR conditions: Weather conditions below the minimum for flight under visual flight rules. (FAR Part 1)
ILS: Instrument Landing System.
ILS Category I: An ILS which provides acceptable guidance information from the coverage limits of the ILS to the point at which the localizer course line intersects the glide path at a height of 100 feet above the horizontal plane containing the runway threshold. A Category I ILS supports landing minima as low as
200 ft. HAT and 1800 RVR. (FAA Order 1000.15A)
ILS Category II: An ILS which provides acceptable guidance information from the coverage limits of the ILS to the point at which the localizer course line intersects the glide path at a height of 50 feet above the horizontal plane containing the runway threshold. A Category II ILS supports landing minima as low as
100 feet HAT and 1200 RVR. (FAA Order 1000.15A)
ILS Category III: An ILS which provides acceptable guidance information from the coverage limits of the ILS with no decision height specified above the horizontal plane containing the runway threshold.
See ILS-CAT III A-B-C operations . (FAA Order 1000.15A)
ILS-CAT III A operation: Operation, with no decision height limitation, to and along the surface of the runway with a runway visual range not less than 700 feet. (FAA Order 1000.15A)
ILS-CAT III B operation: Operation, with no decision height limitation, to and along the surface of the runway without reliance on external visual reference; and, subsequently, taxiing with external visual reference with a runway visual range not less than 150 feet. (FAA Order 1000.15A)
ILS CAT III C operation: Operation, with no decision height limitation, to and along the surface of the runway and taxiways without reliance on external visual reference. (FAA Order 1000.15A)
inactive airport: An airport where all flying activities have ceased yet has remained in an acceptable state of repair for civil use and is identifiable from the air as an airport. (FAA Order 1000.15A)
INM: Integrated Noise Model; FAA computer program used to generate noise contours of equal sound levels.
inner marker (IM): An ILS navigational facility in the terminal area navigation system located between the middle marker and the end of the ILS runway, transmitting a 75 megahertz fan shaped radiation pattern modulated at 3000 Hz, keyed at six dots per second and received by compatible airborne equipment indicating to the pilot, both aurally and visually, that he is directly over the facility at an altitude of 100 feet on his final ILS approach, providing he is on the glide path. (FAA Order 1000.15A)
in-runway lighting: A lighting system consisting of flush or semi-flush lights placed in the runway pavement in specified patterns. (FAA Order 1000.15A)
instrument approach aids: An approach to an airport during which the pilot navigates solely by instruments for some period of time.
instrument approach: An approach to an airport, with intent to land, by an aircraft flying in accordance with an IFR flight plan, when the visibility is less than 3 miles and/or when the ceiling is at or below the minimum initial altitude. (FAA Order 1000.15A)
instrument approach runway: A runway served by an electronic aid providing at least directional guidance adequate for a straight-in approach. (FAA Order 1000.15A)
Instrument Flight Rules (IFR): Rules governing the procedures for conducting instrument flight. Pilots are required to follow these rules when operating in controlled airspace with a visibility of less than three miles and/or a ceiling lower than 1,000 feet.
instrument landing system (ILS): A system which provides in the aircraft, the lateral, longitudinal, and vertical guidance necessary for a landing. (FAA Order 1000.15A)
instrument meteorological conditions (IMC): Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling less than the minima specified for visual meteorological conditions.
(FAA Order 1000.15A)
instrument operation: A take-off or landing of an aircraft that has an instrument flight clearance.
instrument runway: A runway equipped with electronic and visual navigation aids and for which a straight-in (precision or non-precision) approach procedure has been approved or is planned.
intersecting runways: Two or more runways which cross or meet within their lengths. (FAA Order 1000.15A)
itinerant operations: All aircraft arrivals and departures other than local operations. (FAA Order 1000.15A)
jet noise: The noise generated externally to a jet engine in the turbulent jet exhaust. (FAA Order 1000.15A)
Joint Automated Weather Observation System (JAWOS): Automatically gathers local weather data and distributes it to other air traffic control facilities and to the National Weather Service.
joint-use airport: An airport owned by the military, a public body, or both, where an agreement exists for joint civil-military fixed-based aviation operations. (FAA Order 1000.15A)
landing area: any locality, either on land or water, including airports, heliports and STOLports, which is used or intended to be used for the landing and takeoff or surface maneuvering of aircraft, whether or not facilities are provided for the shelter, servicing, or repair of aircraft, or for receiving or discharging of passengers or cargo. (FAA Order 1000.15A)
landing gear: That part of an aircraft which is required for landing. Gear may be configured as Single Wheel Gear (SWG), Dual Wheel Gear (DWG), or Dual Tandem Wheel Gear (DTWG).
landing roll: The distance from the point of touchdown to the point where the aircraft can be brought to a stop, or exit the runway. (FAA Order 1000.15A)
landing strip: A term formerly used to designate: (1) the graded area upon which the runway was symmetrically located and, (2) the graded area suitable for the takeoff and land of airplanes where a paved runway was not provided. (FAA Order 1000.15A)
landside operations: Those parts of the airport designed to serve passengers including the terminal buildings, vehicular circular drive, and parking facilities.
land use plan: Shows on-airport land uses as developed by the airport sponsor under the master plan effort and off-airport land uses as developed by surrounding communities.
large aircraft: Aircraft of more than 12,500 pounds maximum certificated takeoff weight. (FAR Part 1)
Ldn: The Ldn is the 24-hour average sound level, in decibels, for the period from midnight to midnight, obtained after the addition of ten decibels to sound levels for the periods between midnight and 7 a.m. and between 19 o.m. and midnight, local time, as averaged over a span of one year. It is the FAA standard metric for determining the cumulative exposure of individuals to noise.
lighted airport: An airport where runway and associated obstruction lighting is available from sunset to sunrise or during periods of reduced visibility or on request of the pilot. (FAA Order 1000.15A)
localizer: A non-precision NAVAID which gives electronic directional guidance to a specific runway to pilots approaching for a landing. (FAA Order 1000.15A)
localizer beacon: An ILS navigation facility in the terminal area electronic navigation system, providing horizontal guidance to the runway centerline for aircraft during approach and landing by radiating a directional pattern of VHF radio waves modulated by two signals which, when received with equal intensity, are displayed by compatible airborne equipment as an "on-course" indication, and when received in unequal intensity are displayed as an "off-course" indication. (FAA Order 1000.15A)
local operations: As pertaining to air traffic operations, aircraft operating in the local traffic pattern or within sight of the tower; aircraft known to be departing for, or arriving from, flight in local practice areas located within a 20-mile radius of the control tower; aircraft executing simulated instrument approaches or low passes at the airport. (FAA Order 1000.15A)
local traffic: Aircraft operating in the local traffic pattern or within sight of the tower, or aircraft known to be departing for or arriving from flight in local practice areas, or aircraft executing simulated instrument approaches at the airport. (FAA Order 1000.15A)
local VFR flight plan: Specific information provided to air traffic service units, relative to the intended flight of an aircraft under visual flight rules within a specific local area. (FAA Order 1000.15A)
location map: Shown on the airport layout plan drawing, it depicts the airport, cities, railroads, major highways, and roads within 20 to 50 miles of the airport.
low-intensity light: A runway or threshold light from which the light distribution through 360 degrees of azimuth and a selected 6 degrees in the vertical is not less than 10 candlepower in white light. (FAA Order 1000.15A)
Low Level Wind Shear Alert System (LLWSAS): Provides the air traffic control tower with information on wind conditions near the runway. It consists of an array of anemometers that read wind velocity and direction around the airport and signal the sudden changes that indicate wind shear.
MALSR: A medium intensity approach lighting system with runway alignment indicator lights.
marking: On airports, a pattern of contrasting colors placed on the pavement, turf, or other usable surface by paint or other means to provide specific information to aircraft pilots and sometimes to operators of ground vehicles, on the movement areas. (FAA Order 1000.15A)
metering: Regulating the arrival time of aircraft in the terminal area so as not to exceed a given acceptance rate.
Microwave Landing System (MLS): An advanced form of precision approach system (MLS) equipment with improved accuracy and fewer siting problems than current ILS. An MLS also can permit curved path approaches to the runway instead of requiring a straight path as an ILS and PAR do (FAA Order 1000.15A)
middle marker (MM): An ILS navigation facility in the terminal area navigation system located approximately 3,500 feet from the runway edge on the extended centerline, transmitting a 75 MHz fan-shaped radiation pattern, modulated at 1,300 Hz, keyed alternately dot and dash, and received by compatible airborne equipment, indicating to the pilot both aurally and visually, that he is passing over the facility. (FAA Order 1000.15A)
MIRL: Medium Intensity Runway Lighting.
missed approach procedure: Flight prescribed when an aircraft fails to land after completing an instrument approach. (FAA Order 1000.15A)
multi-engine aircraft: Reciprocating turbo-prop or jet powered fixed wing aircraft having more than one engine and categorized as weighing more than or less than 12,500 pounds maximum gross weight.
municipally operated airport: An airport owned by a city and run as a department of the city, with policy direction by the city council and, in some cases, by a separate airport commission or advisory board.
National Airport System Plan (NASP): A plan specifying in terms of general location and type of development the projects considered by the Administrator to be necessary to provide a system of public airports adequate to anticipate and meet the needs of civil aeronautics. See criteria for inclusion in NASP.
National Plan of Integrated Airport Systems (NPIAS): A plan prepared by the FAA which identifies, for the Congress and the public, the composition of a national system of airports together with the airport development necessary to anticipate and meet the present and future needs of civil aeronautics, to meet requirements in support of the national defense, and to meet the special needs of the postal service. The plan includes both new facilities and qualitative improvements to existing airports to increase their capacity, safety, technological capability, etc., (FAA Order 1000.15A)
national system of airports: The inventory of selected civil airports that are highly correlated with those aviation demands most consistent with the national interest. (FAA Order 1000.15A)
nautical miles (international): By international agreement, adopted July 1, 1954, an International Nautical Mile is equal to 6,076.10333 feet. To convert International Nautical Miles to statute miles, multiply by 1.150779. (FAA Order 1000.15A)
National Transportation Safety Board (NTSB): Created by the act which established the Department of Transportation to determine the cause of transportation accidents and review on appeal the suspension or revocation of any certificates or licenses issued by the Secretary of Transportation.
NAVAID: Any facility used in, available for use in, or designated for use in aid of air navigation, including lights, any apparatus of equipment for disseminating weather information, for signaling, for radio direction finding, or for radio or other electronic communication, and any other structure or mechanism having a similar purpose for guiding or controlling flight in the air or the landing or takeoff of aircraft. (FAA Order 1000.15A)
navigable airspace: Airspace at and above the minimum flight altitudes prescribed in the FARs, including airspace needed for safe takeoff and landing. (FAR Part 1)
noise contour: A continuous line on a map of the airport vicinity connecting all points of the same noise exposure level; for the purposes of the INM program, usually the Ldn 65, 70 & 75 levels.
nondirectional beacon(NDB): An NDB transmits nondirectional signals on which a pilot may take a bearing and home in on the station (FAA Order 1000.15A)
noise level: For airborne sound, the same as sound level, unless otherwise specified.
nondepreciable investment items: Those assets such as the cost of land acquisition which have a permanent value even if the airport site is converted to other uses.
noninstrument runway: A runway intended for the operation of aircraft using visual approach procedures. (See visual runway).
nonprecision instrument runway: A runway having an existing instrument approach procedure utilizing air navigation facilities with only horizontal guidance for which a straight-in nonprecision instrument approach procedure has been approved. (FAA Order 1000.15A)
nonprecision approach procedure: A standard instrument approach procedure in which no electronic glideslope is provided. (FAR Part 1)
nonprecision instrument approach aid: An electronic aid designed to provide an approach path for aligning an aircraft on its final approach to a runway. It lacks the high accuracy of the precision approach equipment and does not provide descent guidance. The VHF Omnirange (VOR) and the nondirectional beacon (NDB) are two examples of nonprecision instrument equipment.
Notice to Airman (NOTAM): A notice containing information (not known sufficiently in advance to publicize by other means) concerning the establishment, condition, or change in any component (facility, service, or procedure) of, or hazard in the National Airspace System, the timely knowledge of which is essential to personnel concerned with flight operations. (FAA Order 1000.15A)
Objective of the Airport Master Plan: To provide guidelines for future development of the airport which will satisfy aviation demand and be compatible with the environment, community development, other modes of transportation, and other airports.
obstruction: An object which penetrates an imaginary surface described in the FAA's Federal Aviation Regulations (FAR), Part 77. (FAA Order 1000.15A)
obstruction light: A light, or one of a group of lights, usually red, mounted on a surface structure or natural terrain to warn pilots of the presence of a flight hazard; either an incandescent lamp with a red globe or a strobe light. (FAA Order 1000.15A)
obstruction marking/lighting: Distinctive marking and lighting to provide a uniform means for indicating the presence of obstructions. (FAA Order 1000.15A)
Omnidirectional Approach Lighting System (ODALS): The Omnidirectional Approach Lighting System (ODALS) consists of seven omnidirectional flashing units five of which are spaced outward from the threshold of a runway and arranged to flash in sequence. The other two units are positioned as Runway End Identifier Lights (REILs) on each side of the threshold.
operating statement: Records an airport's revenues and expenses over a particular time period (quarterly and annually).
operational activity forecasts: Include forecasts of operations by major user categories (air carrier, commuter, general aviation, and military).
organization chart: Shows the formal authority relationships between superiors and subordinates at various levels, as well as the formal channels of communication within the organization.
overlay: A pavement structure constructed on top of an existing pavement to increase bearing strength or to improve surface properties.
overrun: To run off the end of the runway after touching down on the runway. (FAA Order 1000.15A)
overrun area: In military aviation exclusively, that area beyond the end of the designated runway with a stabilized surface of the same width as the runway and centered on the extended runway centerline. (FAA Order 1000.15A)
parallel runways: Two or more runways at the same airport whose centerlines are parallel. Designated both by runway number and L (left) or R (right), or, if three parallel runways exist, L (left), C (center), and R (right).
parallel taxiways: Two taxiways which are parallel to one another which allow traffic to move simultaneously in different directions at busy airports.
parking apron: An apron intended to accommodate parked aircraft. (FAA Order 1000.15A)
pavement grooving: The mechanical serration of a pavement surface to provide escape paths for water and slush, to promote improved aircraft mechanical braking effectiveness. (FAA Order 1000.15A)
pavement structure: The combination of runway base and subbase courses and surface course which transmits the traffic load to the subgrade. (FAA Order 1000.15A)
pavement subgrade: The upper part of the soil, natural or constructed, which supports the loads transmitted by the runway pavement structure.
pavement surface course: The top course of a pavement, usually Portland cement concrete or bituminous concrete, which supports the traffic load.
Positive Controlled Airspace (PCA): Any volume of airspace for which the following prerequisites for use apply:
- An air traffic control clearance is required prior to entry.
- The aircraft must be equipped with a specified minimum level of avionics (two-way air ground communications; navigational aids; and beacon transponder.
- The pilot at least has a specified minimum rating and must observe the procedure specified for the airspace.
practical capacity: The number of operations (takeoffs and landings) that can be accommodated with no more than a given amount of delay, usually expressed in terms of maximum acceptable average delay.
precision approach: A standard instrument approach using a precision approach procedure See precision approach procedure. (FAA Order 1000.15A)
precision approach path indicator (PAPI): A system of lights on an airport that provides visual descent guidance to the pilot of an aircraft approaching a runway.
precision approach procedure: A standard instrument approach procedure in which an electronic glideslope is provided, such as ILS and PAR. (FAR Part 1)
precision approach runway: See precision instrument runway.
precision instrument approach aid: An electronic aid designed to provide an approach path for exact alignment and descent guidance of an aircraft on final approach to a runway, instrument landing system (ILS) precision approach radar (PAR), and microwave landing system (MLS) are the existing precision instrument approach aids.
precision instrument runway: A runway having an existing instrument approach procedure utilizing an instrument landing system (ILS) or a precision approach radar (PAR). It also means a runway for which a precision approach system is planned and is so indicated by an FAA approved airport layout plan; a military service approved military airport layout plan; any other FAA planning document, or military service military airport planning document. (FAR Part 77)
primary service airport: Primary service airports are public use airports which receive scheduled passenger service aircraft and which annually enplane a minimum of 10,000 passengers on one one-hundredth percent (0.01%) or more of the combined total domestic passenger enplanements for all United States air carriers. (FAA Order 1000.15A)
primary surface: A rectangular surface longitudinally centered about a runway. Its width is a variable dimension and it usually extends 200 feet beyond each end of the runway. The elevation of any point on this surface coincided with the elevation of its nearest point on the runway centerline or extended runway centerline (FAR Part 77).
public airport: An airport for public use, publicly owned and under control of a public agency. (FAA Order 1000.15A)
public-use airport: An airport open to the public without prior permission and without restrictions within the physical capacities of available facilities. (FAA Order 1000.15A)
radar (radio detection and ranging): A device which, by measuring the time interval between transmission and reception of radio pulses and correlating the angular orientation of the radiated antenna beam or beams in azimuth and/or elevation, provides information on range, azimuth, and/or elevation of objects in the path of the transmitted pulses (AIM, Part 1).
radar approach control (RAPCON or RAPCO): A joint-use air traffic control facility, located at a U.S. Air Force Base, utilizing surveillance and precision approach radar equipment in conjunction with air/ground communication equipment, providing for the safe and expeditious movement of air traffic within the controlled airspace of that facility. (FAA Order 1000.15A)
ramp: A defined area, on a land airport, intended to accommodate aircraft for purposes of loading or unloading passengers or cargo, refueling, parking, or maintenance. (FAA Order 1000.15A)
Regional Airport Planning: Air transportation planning for the region as a whole including all airports in the region, both large and small.
reliever airport: Reliever airports are general aviation airports which have the function of relieving congestion at a primary service airport and which provide the general aviation user with an alternate for access to the overall community. Reliever airports receive higher priority for funding assistance than other general aviation airports.
revenue bonds: Bonds which are payable solely from the revenues derived from the operation of a facility which was constructed or acquired with the proceeds of the bonds.
rigid pavement: A pavement structure consisting of Portland cement concrete that may or may not include a subbase course. (FAA Order 1000.15A)
rotating lighted beacon: A visual aid allowing pilots the ability to locate an airport while flying under VFR conditions at night. At civil airports, alternating white and green flashes indicate the location of an airport.
rotorcraft: A heavier-than-air aircraft that depends principally for its support inflight on the lift generated by one or more rotors. (FAR Part 1)
runway: A defined rectangular area on a land airport prepared for the landing and takeoff run of aircraft along its length. (FAA Order 1000.15A)
runway alignment indicator light (RAIL): This airport lighting facility in the terminal area consists of five or more sequenced flashing lights installed on the extended centerline of the runway. The maximum spacing between lights is 200 feet, extending out from 1,600 feet to 3,000 feet from the runway threshold. Even when collocated with MALS, RAIL will be identified as a separate facility (FAA Order 1000.15A)
runway bearing: The magnetic or true bearing of the runway centerline as measured from magnetic or true North. (FAA Order 1000.15A).
runway capacity: The number of aircraft operations which can be accommodated by a runway without undue delay to aircraft. Undue delays are when delays to departures average four minutes during the normal peak two-hour period of the week. (FAA Order 1000.15A)
runway centerline lighting system: The runway centerline lighting system consists of single lights installed at uniform intervals along the runway centerline so as to provide a continuous lighting reference from threshold to threshold. (FAA Order 1000.15A)
runway configuration: Layout or design of a runway or runways, where operations on the particular runway or runways being used at a given time are mutually dependent. A large airport can have two or more runway configurations operating simultaneously. (FAA Order 1000.15A)
runway contamination: Deposition or presence of dirt, grease, rubber, or other materials on runway surfaces which adversely affect normal aircraft operation or which chemically attack the pavement surface. (FAA Order 1000.15A)
runway direction number: A whole number to the nearest one tenth of the magnetic bearing of the runway and measured in degrees clockwise from magnetic north. (FAA Order 1000.15A)
runway end identification lights (REIL): An airport lighting facility in the terminal area navigation system consisting of one flashing white high intensity light installed at each approach end corner of a runway and directed toward the approach zone, which enables the pilot to identify the threshold of a usable runway. (FAA Order 1000.15A)
runway environment: The runway threshold or approach lighting aids or other markings identifiable with the runway. (FAA Order 1000.15A)
runway gradient (effective): The average gradient consisting of the difference in elevation of the two ends of the runway divided by the runway length may be used provided that no intervening point on the runway profile lies more than 5 feet above or below a straight line joining the two ends of the runway. In excess of 5 feet, the runway profile will be segmented and aircraft data will be applied for each segment separately. (FAA Order 1000.15A)
runway grooving: One-quarter inch grooves spaced approximately one-and-one-quarter inch apart made in the runway surface designed to provide better drainage, furnish escape routes for water under the tire footprint to prevent hydroplaning.
runway length-landing: The measured length from the threshold to the end of the runway. (FAA Order 1000.15A)
runway length-physical: The actual measured length of the runway. (FAA Order 1000.15A)
runway length-takeoff: The measured length from where the takeoff is designated to begin to the end of the runway. (FAA Order 1000.15A)
runway lighting system: A system of lights running the length of a runway that may be either high intensity (HIRL), medium intensity (MIRL), or low intensity (LIRL). (FAA Order 1000.15A)
runway lights: Lights having a prescribed angle of emission used to define the lateral limits of a runway. Runway light intensity may be controllable or preset, and are uniformly spaced at intervals of approximately 200 feet.
runway markings: (1) Visual marking--markings on runways used for operations under visual flight rules, consisting of centerline marking and runway direction numbers, and if required, letters. (2) Instrument marking--markings on runways served by nonvisual navigation aids and intended for landings under instrument weather conditions, consisting of basic marking plus threshold marking. (3) All-weather marking--markings on runways served by nonvisual precision approach aids and on runways having special operational requirements, consisting of instrument markings plus landing zone marking and side strips (FAA Order 1000.15A)
runway orientation: The magnetic bearing of the centerline of the runway. (FAA Order 1000.15A)
runway protection zone (formerly "clear zone"): A runway protection zone is a trapezoidal area at ground level, under the control of the airport authorities, for the purpose of protecting the safety of approaches and keeping the area clear of the congregation of people. The runway protection zone begins at the end of each primary surface and is centered upon the extended runway centerline, and extends outwards to a point where the approach surface reaches a height of 50 feet above the elevation of the runway end.
runway safety area: A runway safety area is a rectangular area, centered on the runway centerline, which includes the runway (and stopway, if present) and the runway shoulders. The portion abutting the edge of the runway shoulders, runway ends, and stopways is cleared, drained, graded, and usually turfed. Under normal conditions, the runway safety area is capable of supporting snow removal, firefighting, and rescue equipment and accommodating the occasional passage of aircraft without causing major damage to the aircraft.
runway strength: The assumed ability of a runway to support aircraft of a designated gross weight for each of single-wheel, dual-wheel, and dual-tandem-wheel gear types. (FAA Order 1000.15A)
runway surface lighting: Also referred to as "in-runway lighting," consisting essentially of touchdown zone (narrow gauge) lights, runway centerline lights, and exit taxiway turnoff lights, installed in the pavement.
runway threshold marking: Markings so placed as to indicate the longitudinal limits of that portion of the runway usable for landing. (FAA Order 1000.15A)
runway visibility: Visibility determined by a transmissometer associated with the instrument runway(s) or by an observer stationed at the approach end of the runway. (FAA Order 1000.15A)
runway visual range (RVR): An instrumentally derived value that represents the horizontal distance a pilot can see down the runway from the approach end; it is based on the sighting of either high intensity runway lights or on the visual contrast of other targets whichever yields the greater visual range. (FAA Order 1000.15A)
satellite terminals: A type of terminal layout in which all passenger processing is done in a single terminal which is connected by concourses to one or more satellite structures. The satellite generally has a common waiting room which serves a number of gate positions.
scheduled service: Transport service operated over routes based on published flight schedules, including extra sections and related nonrevenue flights. (FAA Order 1000.15A)
secondary runway: A runway which provides additional wind coverage or capacity to expedite traffic handling. (FAA Order 1000.15A)
segmented circle: A system of visual indicators designed to provide traffic pattern information at an airport without an operating control tower.
sequencing: Specifying the exact order in which aircraft will take off or land.
short takeoff and landing (STOL) aircraft: An aircraft which, at some weight within its approved range of STOL operating weight, is capable of operating from a STOL runway in compliance with the applicable STOL characteristics, airworthiness, operations, noise, and pollution standards. (FAA Order 1000.15A)
shoulder: As pertaining to airports, an area adjacent to the edge of a paved surface so prepared to provide a transition between the pavement and the adjacent surface for aircraft running off the pavement, for drainage and sometimes for blast protection. (FAA Order 1000.15A)
single runway: An airport having one runway.
slot: A block of time allocated to an airport user to perform an aircraft operation (takeoff or landing).
small aircraft: Aircraft of 12,500 pounds or less maximum certificated takeoff weight. (FAR Part 1)
spalling: Fractured edges in and around the joint area of concrete due to the tremendous pressures generated during expansion and contraction of the slabs.
Standard Air Carrier Delay Reporting System (SDRS): Contains reports from American, Eastern, and United Airlines regarding delays on their entire systems and at 32 specific airports.
State Aviation System Plans (SASP): Plan for the development of airports within the state.
STOL: Short takeoff and landing.
STOLport: An airport specifically designed for STOL aircraft, separate from conventional airport facilities. (FAA Order 1000.15A)
straight-in approach (IFR): An instrument approach wherein final approach is commenced without first having executed a procedure turn. (Not necessarily completed with a straight-in landing. (AIM, Part 1)
straight-in approach (VFR): Entry into the traffic pattern by interception of the extended runway centerline without executing any other portion of the traffic pattern. (AIM, Part 1)
stub taxiway: A short connecting taxiway to an airport facility that serves as the only connection with the remaining airport complex. (FAA Order 1000.15A)
taxiway: A defined path, usually paved, over which aircraft can taxi from one part of an airport to another. (FAA Order 1000.15A)
taxiway centerline lighting: A system of flush or semiflush in-pavement lights indicating the taxiway centerline. (FAA Order 1000.15A)
taxiway safety area: A cleared, drained, and graded area, symmetrically located about the extended taxiway centerline and adjacent to the end of the taxiway safety area. (FAA Order 1000.15A)
taxiway turnoff lighting: Single lights installed in the pavement at uniform intervals to define the path of aircraft travel from the runway centerline to a point on the taxiway. (FAA Order 1000.15A)
taxiway turnoff markings: Signs or lights along the runways, taxiways, and ramp surfaces of an airport used to assist a pilot in finding his way. (FAA Order 1000.15A)
terminal apron: An area provided for parking and positioning of aircraft in the vicinity of the terminal building for loading and unloading.
terminal area: The area used or intended to be used for such facilities as terminal and cargo buildings, gates, hangars, shops, and other service buildings; automobile parking, airport motels and restaurants, and garages and vehicle service--facilities used in connection with the airport; and entrance and service roads used by the public within the boundaries of the airport.
terminal area capacity: The ability of the terminal area to accept the passengers, cargo, and aircraft that the airfield accommodates.
terminal building: A building or buildings designed to accommodate the enplaning and deplaning activities of air carrier passengers. (FAA Order 1000.15A)
terminal facilities: The airport facilities providing services for air carrier operations which serve as a center for the transfer of passengers and baggage between surface and air transportation. (FAA Order 1000.15A)
terminal very high frequency omnidirectional range station: An electronic navigation aid that provides guidance, both for enroute flights on low altitude "Victor" airways and for (TVOR) nonprecision approaches. Also see nonprecision approach aid.
tetrahedron: A device with four triangular sides which indicates wind direction and which may be used as a landing direction indicator. (FAA Order 1000.15A)
T-hangar: An aircraft hangar in which aircraft are parked alternately tail to tail, each in the T-shaped space left by the other row of aircraft or aircraft compartments. (FAA Order 1000.15A)
threshold: The designated beginning of the runway that is available and suitable for the landing of airplanes. (FAA Order 1000.15A).
threshold crossing height (TCH): The height of the straight-line extension of the visual or electronic glideslope above the runway threshold (AIM, Part 1).
threshold lights: Lighting arranged symmetrically about the extended centerline of the runway identifying the runway threshold. They emit a fixed green light. (FAA Order 1000.15A)
throughput capacity: The rate at which aircraft can be brought into or out of the airfield, without regard to any delay they might experience.
touch-and-go operations: Practice flight performed by a landing, touchdown, and continuous takeoff without stopping. (FAA Order 1000.15A)
total operations: All arrivals and departures performed by military, general aviation, and air carrier aircraft.
touchdown: (1) The point at which an aircraft first makes contact with the landing surface. (2) In a precision radar approach, the point on the landing surface toward which the controller issues guidance instructions. (FAA Order 1000.15A)
touchdown zone: The area of a runway near the approach end where airplanes normally alight. (FAA Order 1000.15A)
touchdown zone lighting: This system in the runway touchdown zone area presents, in plain view, two rows of transverse light bars located symmetrically about the runway centerline. The basic system extends 3,000 feet along the runway. (FAA Order 1000.15A)
tower: See airport traffic tower. (FAA Order 1000.15A)
traffic pattern: The traffic flow that is prescribed for aircraft landing at, taxiing on, and taking off from an airport. The usual components of a traffic pattern are upwind leg, crosswind leg, downwind leg, base leg, and final approach. (FAR Part 1)
transient: Operations or other activity performed by aircraft not based at the airport.
transitional surface: A surface which extends outward and upward from the sides of the primary and approach surfaces normal to the runway centerline which identifies the height limitations on an object before it becomes an obstruction to air navigation. (FAA Order 1000.15A)
transition area: Controlled airspace extending upward from 700 feet or more above the surface of the Earth when designated in conjunction with an airport for which an instrument approach procedure has been prescribed; or from 1,200 feet or higher above the surface of the Earth when designated in conjunction with airway route structures or segments. Unless otherwise limited, transition areas terminate at the base of the overlying controlled airspace. (FAA Order 1000.15A)
turnaround: A taxiway adjacent to the runway ends which aircraft use to change direction, hold, or bypass other aircraft. (FAA Order 1000.15A)
turning radius: The radius of the arc described by an aircraft in making a self-powered turn, usually given as a minimum. (FAA Order 1000.15A)
turnoff taxiway: A taxiway specifically designed to provide aircraft with a means to expedite clearing a runway. (FAA Order 1000.15A)
typical peak-hour passenger volume (design volume): The peak hour of an average day in the peak month which is used as the hourly design volume for terminal space.
undershoot: To touch down short of the point of intended landing. (FAA Order 1000.15A)
UNICOM: Frequencies authorized for aeronautical advisory services to private aircraft. Only one such station is authorized at any landing area. The frequency 123.0 MHz is used at airports served by airport traffic control towers, and 122.8 MHz is used for other landing areas. Services available are advisory in nature, primarily concerning the airport services and airport utilization. (FAA Order 1000.15A)
upwind leg: A flight path parallel to the landing runway in the direction of landing. (FAA Order 1000.15A)
VFR: Visual Flight Rules. (FAR Part 91)
VFR airport: An airport without an authorized or planned instrument approach procedure; also, a former airport design category indicating an airport serving small aircraft only and not designed to satisfy the requirements of instrument landing operations. (FAA Order 1000.15A)
VFR tower: An airport traffic control tower that does not provide approach control service. (FAA Order 1000.15A)
VHF: Very high frequency.
VHF omnidirectional range (VOR): A radio transmitter facility in the navigation system radiating a VHF radio wave modulated by two signals, the relative phases of which are compared, resolved, and displayed by a compatible airborne receiver to give the pilot a direct indication of bearing relative to the facility. (FAA Order 1000.15A)
vicinity map: Shown on the airport layout plan drawing, it depicts the relationship of the airport to the city or cities, nearby airports, roads, railroads, and built-up areas.
visual approach: An approach wherein an aircraft on an IFR flight plan, operating in VFR conditions under the control of a radar facility and having an air traffic control authorization, may deviate from the prescribed instrument approach procedure and proceed to the airport of destination, served by an operational control tower, by visual reference to the surface. (FAR, Part 1)
visual approach aid: Any device, light, or marker used to provide visual alignment and/or descent guidance on final approach to a runway. Also see REIL, VASI.
visual approach slope indicator (VASI): An airport approach lighting facility used primarily under VFR conditions. It provides vertical visual guidance to aircraft during approach and landing by radiating a directional pattern of high intensity red and white focused light beams which indicate to the pilot that he is "on path" if he sees red/white, "above path" if white/white, and "below path" if red/red. (FAA Order 1000.15A)
Visual Flight Rules (VFR): Rules that govern the procedures for conducting flight under visual conditions. (FAR Part 91)
visual runway: A runway intended solely for the operation of aircraft using visual approach procedures, with no straight-in instrument approach procedure and no instrument designation indicated on an FAA-approved airport layout plan, a military service approved military airport layout plan, or by a planning document submitted to the FAA by competent authority. (FAR Part 77)
VMC: Visual meteorological conditions.
VOR: Very high frequency omnidirectional range.
VORTAC: Very High Frequency Omni Range Facility co-located with a Tactical Air Navigation (TACAN) facility.
V/STOL: Vertical/short takeoff and landing.
vortices: As pertaining to aircraft, circular patterns of air created by the movement of an airfoil through the atmosphere. As an airfoil moves through the atmosphere in sustained flight, an area of high pressure is created beneath it and an area of low pressure is created above it. The air flowing from the high pressure area to the low pressure area around and about the tips of the airfoil tends to roll up into two rapidly rotating vortices, cylindrical in shape. These vortices are the most predominant parts of aircraft wake turbulence and their rotational force is dependent upon the wing loading, gross weight, and speed of the generating aircraft. (FAA Order 1000.15A)
wake vortex: A phenomenon resulting from the passage of an aircraft through the atmosphere. It is an aerodynamic disturbance that originates at the wingtips and trails in corkscrew fashion behind the aircraft. When used by ATC it includes vortices, thrust stream turbulence, jet wash, propeller wash, and rotor wash.
wind cone: A free-rotating fabric truncated cone which when subjected to air movement indicates wind direction and wind force. (FAA Order 1000.15A)
wind rose: A diagram for a given location showing relative frequency and velocity of wind from all compass directions. (FAA Order 1000.15A)
wind shear: Variation of wind speed and wind direction with respect to a horizontal or vertical plane. Low-level shear in the terminal area is a factor in the safe and expeditious landing of aircraft.
wind tee: A T-shaped free rotating device to indicate wind direction. Sometimes capable of being secured for use as a landing direction indicator.
Zulu time (Z): Time at the prime meridian in Greenwich, England. (FAA Order 1000.15A)
ABBREVIATIONS / ACRONYMS
AAA: Airport Airspace Analysis
AAS: Airport Advisory Service
AC: Advisory Circular
ADAP: Airport Development Aid Program
ADC: Air Defense Command
ADF: Automatic Direction Finder
ADG: Airplane Design Group
AFSS: automated flight service station
AID: Airport Information Desk
AIM: Airman's Information Manual
AIP: Airport Improvement Program
AIREP: Air Report
AIRMET: Airmen's Meteorological Information
ALNOT: Alert Notice
ALP: Airport Layout Plan
ALS: Approach Lighting System
ALSF: approach lighting system with sequenced flashing lights
AMIS: Aircraft Movement Information Service
ARC: Airport Reference Code
ARP: Airport Reference Point
ARSR: Air Route Surveillance Radar
ARTCC: Air Route Traffic Control Center
ARTS: Automated Radar Terminal System
ASDA: Accelerate-Stop Distance Available
ASDE: Airport Surface Detection Equipment
ASOS: automated surface observing system
ASR: Airport Surveillance Radar
ATC: Air Traffic Control (FAR Part I)
ATCRBS: Air Traffic Control Radar Beacon System
ATCSCC: ATC Systems Command Center
ATCT: Airport Traffic Control Tower
ATIS: Automatic Terminal Information Service
AWOS: automated weather observing system
BRL: Building Restriction Line
CAA: Civil Aeronautics Administration
CAB: Civil Aeronautics Board
CAT: clear-air turbulence
CFCF: Central Flow Control Function
CIP: Capital Investment Plan
CONUS: continental, contiguous, or conterminous United States
CWY: clearway
DABS: Discrete Address Beacon System
dB: Decibel
DF: direction finder
DH: decision height
DME: distance measuring equipment
DOT: Department of Transportation
DVOR: Doppler very high frequency omni-directional range
EFAS: En-Route Flight Advisory Service
EPA: Environmental Protection Agency
EPNL: effective perceived noise level
FAA: Federal Aviation Administration
FAR: Federal Aviation Regulations
FAWS: Flight Advisory Weather Service
FBO: Fixed Base Operator
FSS: Flight Service Station
GCA: ground-controlled approach
GDL: guidance light facility
GPS: global positioning system
GS: ILS glide slope
HAT: height above touchdown
ICAO: International Civil Aviation Organization
IFR: Instrument Flight Rules
(FAR Part 91)
ILS: instrument landing system
IM: inner marker
IMC: Instrument Meteorological Conditions
JAWOS: Joint Automated Weather Observation System
LDA: Landing distance available
LDIN: lead-in light facility
LF: low frequency
LOC: ILS localizer
MALSR: medium-intensity approach lighting system with runway alignment indicator lights
MDA: Minimum descent Altitude
(FAR Part I)
MEA: Minimum En Route IFR Altitude
MLS: microwave landing system
MM: middle marker
MOCA: minimum obstruction clearance altitude
MLS: mean sea level
NAFEC: National Aviation Facilities Experimental Center
NAR: National Airspace Review
NAS: National Airspace System
NASCOM: National Airspace Command Center
NASP: National Airport System Plan
NAVAID: Navigation Aid facility
NDB: Nondirectional beacon
NOTAM: Notice to Airmen
NPIAS: National Plan of Integrated Airport Systems
NTSB: National Transportation Safety Board
NWS: National Weather Service
ODALS: omnidirectional approach lighting system
OFA: Object free area
OFZ: Obstacle free zone
OM: outer marker
OMNI: (See VOR)
PAPI: precision approach path indicator
PAR: precision approach radar
PGP: Planning Grant Program
PIREP: Pilot Report
PMS: performance measurement system
PNL: perceived noise level
RAIL: runway alignment indicator light
RAPCON or
RAPCO: radar approach control
RATCF: Radar Air Traffic Control Facility
REIL: runway end identification lights
RNAV: area navigation
ROT: runway occupancy time
RPZ: runway protection zone
RSA: runway safety area
RVR: runway visual range
RW: runway
SALS: short approach light system
SASP: State Aviation System Plan
SECRA: secondary radar
SFL: sequenced flashing lights
SIGMET: Significant Meteorological Information
SSALF: simplified short approach lighting system with sequenced flashing lights
SSALR: simplified short approach lighting system with runway alignment indicator lights
SSR: secondary surveillance radar
STOL: short takeoff and landing
SWY: stopway
TACAN: Tactical Air Navigation
TCH: threshold crossing height
TERPS: Terminal Instrument procedures
TRACON or
TRACO: Terminal Radar Approach Control
TVOR: Terminal VOR (on airport)
TW: taxiway
UHF: ultra high frequency
USGS: United States Geological Service
VAS: Vortex Advisory System
VASI: Visual Approach Slope Indicator
VFR: Visual Flight Rules (FAR Part 91)
VHF: very high frequency
VMC: Visual Meteorological Conditions
VOR: very high frequency omni-directional range
VORTAC: VOR collocated with TACAN
VTOL: vertical takeoff and land
Z: Zulu Time