Aeronautical Terms beginning with A
A.C.
Alternating current.
A/FD
Airport/Facility Directory—obsolete. Changed to Chart Supplement.
AAI
Arrival Aircraft Interval
AAR
Airport Acceptance Rate or Airport Arrival Rate. The number of arrivals an airport is capable of accepting each hour.
AAS
Airport Advisory Service
Abeam
An aircraft is “abeam” a fix, point, or object when that fix, point, or object is approximately 90 degrees to the right or left of the aircraft track. Abeam indicates a general position rather than a precise point.
Abort
To terminate a preplanned aircraft maneuver; e.g., an aborted takeoff.
Absolute accuracy
The ability to determine present position in space independently, and is most often used by pilots.
Absolute altitude
The actual distance between an aircraft and the terrain over which it is flying.
Absolute pressure
Pressure measured from the reference of zero pressure, or a vacuum.
AC
Advisory Circular
AC, A/C or ACFT
Aircraft
Acceleration
Force involved in overcoming inertia, and which may be defined as a change in velocity per unit of time.
Acceleration error
A magnetic compass error apparent when the aircraft accelerates while flying on an easterly or westerly heading, causing the compass card to rotate toward North.
Acknowledge
Let me know that you have received my message.
ACL
Aircraft List
Acrobatic Flight
An intentional maneuver involving an abrupt change in an aircraft’s attitude, an abnormal attitude, or abnormal acceleration not necessary for normal flight. (Refer to 14 CFR Part 91.
Active Runway
Runway In Use/Active Runway/Duty Runway.
AD
Airworthiness Directive
ADC
Air Data Computer.
ADCUS
Advise Customs
Additional Services
Advisory information provided by ATC which includes but is not limited to the following: a. Traffic advisories. b. Vectors, when requested by the pilot, to assist aircraft receiving traffic advisories to avoid observed traffic. c. Altitude deviation information of 300 feet or more from an assigned altitude as observed on a verified (reading correctly) automatic altitude readout (Mode C). d. Advisories that traffic is no longer a factor. e. Weather and chaff information. f. Weather assistance. g. Bird activity information. h. Holding pattern surveillance. Additional services are provided to the extent possible contingent only upon the controller’s capability to fit them into the performance of higher priority duties and on the basis of limitations of the radar, volume of traffic, frequency congestion, and controller workload. The controller has complete discretion for determining if he/she is able to provide or continue to provide a service in a particular case. The controller’s reason not to provide or continue to provide a service in a particular case is not subject to question by the pilot and need not be made known to him/her.
ADDS
Aviation Digital Data Service
ADF
Automatic Direction Finder.
ADI
Attitude Director Indicator.
ADIZ
Air Defense Identification Zone
Administrator
The Federal Aviation Administrator or any person to whom he has delegated his authority in the matter concerned.
ADS-B
Automatic Dependent Surveillance-Broadcast.
Adverse yaw
A condition of flight in which the nose of an airplane tends to yaw toward the outside of the turn. This is caused by the higher induced drag on the outside wing, which is also producing more lift. Induced drag is a by-product of the lift associated with the outside wing.
Advise Intentions
Tell me what you plan to do.
Advisory
Advice and information provided to assist pilots in the safe conduct of flight and aircraft movement.
Advisory Frequency
The appropriate frequency to be used for Airport Advisory Service.
Advisory Service
Advice and information provided by a facility to assist pilots in the safe conduct of flight and aircraft movement.
ADZY or ADVZY
Advisory
Aerial Refueling
A procedure used by the military to transfer fuel from one aircraft to another during flight.
Aerodrome
A defined area on land or water (including any buildings, installations and equipment) intended to be used either wholly or in part for the arrival, departure, and movement of aircraft.
Aerodrome Beacon [ICAO]
Aeronautical beacon used to indicate the location of an aerodrome from the air.
Aerodrome Control Service [ICAO]
Air traffic control service for aerodrome traffic.
Aerodrome Control Tower [ICAO]
A unit established to provide air traffic control service to aerodrome traffic.
Aerodrome Elevation [ICAO]
The elevation of the highest point of the landing area.
Aerodrome Traffic Circuit [ICAO]
The specified path to be flown by aircraft operating in the vicinity of an aerodrome.
Aerodynamics
The science of the action of air on an object, and with the motion of air on other gases. Aerodynamics deals with the production of lift by the aircraft, the relative wind, and the atmosphere.
Aeronautical Beacon
A visual NAVAID displaying flashes of white and/or colored light to indicate the location of an airport, a heliport, a landmark, a certain point of a Federal airway in mountainous terrain, or an obstruction.
Aeronautical Chart
A map used in air navigation containing all or part of the following: topographic features, hazards and obstructions, navigation aids, navigation routes, designated airspace, and airports. Commonly used aeronautical charts are: Sectional Aeronautical Charts, VFR Terminal Area Charts, World Aeronautical Charts (WAC), En Route Low Altitude Charts, En Route High Altitude Charts, Instrument Approach Procedures (IAP) Charts, Instrument Departure Procedure (DP) Charts, Standard Terminal Arrival (STAR) Charts.
Affirmative
Yes.
AFIS
Automatic Flight Information Service
AFM
Airplane Flight Manual.
AFM
Aircraft Flight Manual
AFSS
Automated Flight Service Station
AGL
Above Ground Level
AGL Altitude
Altitude expressed in feet measured above ground level.
Agonic line
An irregular imaginary line across the surface of the Earth along which the magnetic and geographic poles are in alignment, and along which there is no magnetic variation.
AHRS
Attitude Heading Reference System
Ailerons
Primary flight control surfaces mounted on the trailing edge of an airplane wing, near the tip. Ailerons control roll about the longitudinal axis.
AIM
Aeronautical Information Manual
Air carrier
A person who undertakes directly by lease, or other arrangement, to engage in air transportation.
Air commerce
Interstate, overseas, or foreign air commerce or the transportation of mail by aircraft or any operation or navigation of aircraft within the limits of any Federal airway or any operation or navigation of aircraft which directly affects, or which may endanger safety in, interstate, overseas, or foreign air commerce.
Air Defense Emergency
A military emergency condition declared by a designated authority. This condition exists when an attack upon the continental U.S., Alaska, Canada, or U.S. installations in Greenland by hostile aircraft or missiles is considered probable, is imminent, or is taking place.
Air Defense Identification Zone (ADIZ)
The area of airspace over land or water, extending upward from the surface, within which the ready identification, the location, and the control of aircraft are required in the interest of national security.
Air Navigation Facility
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-directional finding, or for radio or other electrical communication, and any other structure or mechanism having a similar purpose for guiding or controlling flight in the air or the landing and takeoff of aircraft.
Air Route Surveillance Radar
Air route traffic control center (ARTCC) radar used primarily to detect and display an aircraft’s position while en route between terminal areas. The ARSR enables controllers to provide radar air traffic control service when aircraft are within the ARSR coverage. In some instances, ARSR may enable an ARTCC to provide terminal radar services similar to but usually more limited than those provided by a radar approach control.
Air Route Traffic Control Center
A facility established to provide air traffic control service to aircraft operating on IFR flight plans within controlled airspace and principally during the en route phase of flight. When equipment capabilities and controller workload permit, certain advisory/assistance services may be provided to VFR aircraft.
Air route traffic control center (ARTCC)
Provides ATC service to aircraft operating on IFR flight plans within controlled airspace and principally during the en route phase of flight.
Air Traffic
Aircraft operating in the air or on an airport surface, exclusive of loading ramps and parking areas.
Air Traffic Clearance
An authorization by air traffic control for the purpose of preventing collision between known aircraft, for an aircraft to proceed under specified traffic conditions within controlled airspace. The pilot-in-command of an aircraft may not deviate from the provisions of a visual flight rules (VFR) or instrument flight rules (IFR) air traffic clearance except in an emergency or unless an amended clearance has been obtained. Additionally, the pilot may request a different clearance from that which has been issued by air traffic control (ATC) if information available to the pilot makes another course of action more practicable or if aircraft equipment limitations or company procedures forbid compliance with the clearance issued. Pilots may also request clarification or amendment, as appropriate, any time a clearance is not fully understood, or considered unacceptable because of safety of flight. Controllers should, in such instances and to the extent of operational practicality and safety, honor the pilot’s request. 14 CFR Part 91.3(a) states: “The pilot in command of an aircraft is directly responsible for, and is the final authority as to, the operation of that aircraft.” the pilot is responsible to request an amended clearance, if ATC issues a clearance that would cause a pilot to deviate from a rule or regulation, or in the pilot’s opinion, would place the aircraft in jeopardy.
Air Traffic Control
A service operated by appropriate authority to promote the safe, orderly and expeditious flow of air traffic.
Air Traffic Control Clearance [ICAO]
Authorization for an aircraft to proceed under conditions specified by an air traffic control unit. Note 1: For convenience, the term air traffic control clearance is frequently abbreviated to clearance when used in appropriate contexts. Note 2: The abbreviated term clearance may be prefixed by the words taxi, takeoff, departure, en route, approach or landing to indicate the particular portion of flight to which the air traffic control clearance relates.
Air traffic control radar beacon system (ATCRBS)
Sometimes called secondary surveillance radar (SSR), which utilizes a transponder in the aircraft. The ground equipment is an interrogating unit, in which the beacon antenna is mounted so it rotates with the surveillance antenna. The interrogating unit transmits a coded pulse sequence that actuates the aircraft transponder. The transponder answers the coded sequence by transmitting a preselected coded sequence back to the ground equipment, providing a strong return signal and positive aircraft identification, as well as other special data.
Air Traffic Control Service [ICAO]
A service provided for the purpose of: a. Preventing collisions: 1. Between aircraft; and 2. On the maneuvering area between aircraft and obstructions. b. Expediting and maintaining an orderly flow of air traffic.
Air Traffic Control Specialist
A person authorized to provide air traffic control service.
Air Traffic Control System Command Center
An Air Traffic Tactical Operations facility responsible for monitoring and managing the flow of air traffic throughout the NAS, producing a safe, orderly, and expeditious flow of traffic while minimizing delays. The following functions are located at the ATCSCC: a. Central Altitude Reservation Function (CARF). Responsible for coordinating, planning, and approving special user requirements under the Altitude Reservation (ALTRV) concept. b. Airport Reservation Office (ARO). Responsible for approving IFR flights at designated high density traffic airports (John F. Kennedy, LaGuardia, and Ronald Reagan Washington National) during specified hours. c. U.S. Notice to Airmen (NOTAM) Office. Responsible for collecting, maintaining, and distributing NOTAMs for the U.S. civilian and military, as well as international aviation communities. d. Weather Unit. Monitor all aspects of weather for the U.S. that might affect aviation including cloud cover, visibility, winds, precipitation, thunderstorms, icing, turbulence, and more. Provide forecasts based on observations and on discussions with meteorologists from various National Weather Service offices, FAA facilities, airlines, and private weather services.
Air Traffic Service
A generic term meaning: a. Flight Information Service. b. Alerting Service. c. Air Traffic Advisory Service. d. Air Traffic Control Service: 1. Area Control Service, 2. Approach Control Service, or 3. Airport Control Service.
Air Traffic Service (ATS) Routes
The term “ATS Route” is a generic term that includes “VOR Federal airways,” “colored Federal airways,” “jet routes,” and “RNAV routes.” The term “ATS route” does not replace these more familiar route names, but serves only as an overall title when listing the types of routes that comprise the United States route structure.
Air Traffic [ICAO]
All aircraft in flight or operating on the maneuvering area of an aerodrome.
Air transportation
Interstate, overseas, or foreign air transportation or the transportation of mail by aircraft.
Airborne
An aircraft is considered airborne when all parts of the aircraft are off the ground.
Airborne Delay
Amount of delay to be encountered in airborne holding.
Aircraft
A device that is used or intended to be used for flight in the air.
Aircraft altitude
The actual height above sea level at which the aircraft is flying.
Aircraft checkouts
An instructional program designed to familiarize and qualify a pilot to act as pilot in command of a particular aircraft type.
Aircraft Classes
AIRCRAFT CLASSES- For the purposes of Wake Turbulence Separation Minima, ATC classifies aircraft as Super, Heavy, Large, and Small as follows:
a. Super. The Airbus A-380-800 (A388) and the Antonov An-225 (A225) are classified as super.
b. Heavy- Aircraft capable of takeoff weights of 300,000 pounds or more whether or not they are operating at this weight during a particular phase of flight.
c, Large- Aircraft of more than 41,000 pounds, maximum certificated takeoff weight, up to but not including 300,000 pounds.
d. Small- Aircraft of 41,000 pounds or less maximum certificated takeoff weight.
Aircraft Conflict
Predicted conflict, within URET, of two aircraft, or between aircraft and airspace. A Red alert is used for conflicts when the predicted minimum separation is 5 nautical miles or less. A Yellow alert is used when the predicted minimum separation is between 5 and approximately 12 nautical miles. A Blue alert is used for conflicts between an aircraft and predefined airspace.
Aircraft Conflict Alert
A safety alert issued by ATC to aircraft under their control if ATC is aware of an aircraft that is not under their control at an altitude which, in the controller’s judgment, places both aircraft in unsafe proximity to each other. With the alert, ATC will offer the pilot an alternate course of action when feasible; e.g., “Traffic Alert, advise you turn right heading zero niner zero or climb to eight thousand immediately.”
Airfoil
Any surface, such as a wing, propeller, rudder, or even a trim tab, which provides aerodynamic force when it interacts with a moving stream of air.
Airmanship
A sound acquaintance with the principles of flight, the ability to operate an airplane with competence and precision both on the ground and in the air, and the exercise of sound judgment that results in optimal operational safety and efficiency.
Airmen’s Meteorological Information
AIRMET.
AIRMET
Airmen’s Meteorological Information
AIRMET
In-flight weather advisories issued only to amend the area forecast concerning weather phenomena which are of operational interest to all aircraft and potentially hazardous to aircraft having limited capability because of lack of equipment, instrumentation, or pilot qualifications. AIRMETs concern weather of less severity than that covered by SIGMETs or Convective SIGMETs. AIRMETs cover moderate icing, moderate turbulence, sustained winds of 30 knots or more at the surface, widespread areas of ceilings less than 1,000 feet and/or visibility less than 3 miles, and extensive mountain obscurement.
Airplane
An engine-driven fixed-wing aircraft heavier than air, that is supported in flight by the dynamic reaction of the air against its wings.
Airplane Flight Manual (AFM)
A document developed by the airplane manufacturer and approved by the Federal Aviation Administration (FAA). It is specific to a particular make and model airplane by serial number and it contains operating procedures and limitations.
Airplane Owner/Information Manual
A document developed by the airplane manufacturer containing general information about the make and model of an airplane. The airplane owner’s manual is not FAA approved and is not specific to a particular serial numbered airplane. This manual is not kept current, and therefore cannot be substituted for the AFM/POH.
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.
Airport Elevation
The highest point of an airport’s usable runways measured in feet from mean sea level.
Airport Lighting
Various lighting aids that may be installed on an airport.
Airport Marking Aids
Markings used on runway and taxiway surfaces to identify a specific runway, a runway threshold, a centerline, a hold line, etc. A runway should be marked in accordance with its present usage such as: a. Visual. b. Nonprecision instrument. c. Precision instrument.
Airport Reference Point (ARP)
The approximate geometric center of all usable runway surfaces.
Airport Rotating Beacon
A visual NAVAID operated at many airports. At civil airports, alternating white and green flashes indicate the location of the airport. At military airports, the beacons flash alternately white and green, but are differentiated from civil beacons by dualpeaked (two quick) white flashes between the green flashes.
Airport Surface Detection Equipment (ASDE)
Surveillance equipment specifically designed to detect aircraft, vehicular traffic, and other objects, on the surface of an airport, and to present the image on a tower display. Used to augment visual observation by tower personnel of aircraft and/or vehicular movements on runways and taxiways. There are three ASDE systems deployed in the NAS: a. ASDE-3 a Surface Movement Radar. b. ASDE-X a system that uses a X-band Surface Movement Radar and multilateration. Data from these two sources are fused and presented on a digital display. c. ASDE-3X an ASDE-X system that uses the ASDE-3 Surface Movement Radar.
Airport Surveillance Radar
Approach control radar used to detect and display an aircraft’s position in the terminal area. ASR provides range and azimuth information but does not provide elevation data. Coverage of the ASR can extend up to 60 miles.
Airport Taxi Charts
Aeronautical Chart.
Airport Traffic Control Service
A service provided by a control tower for aircraft operating on the movement area and in the vicinity of an airport.
Airport Traffic Control Tower
Tower.
Airport/Facility Directory
A publication designed primarily as a pilot’s operational manual containing all airports, seaplane bases, and heliports open to the public including communications data, navigational facilities, and certain special notices and procedures. This publication is issued in seven volumes according to geographical area. (Renamed to Chart Supplement)
Airship
An engine-driven lighter-than-air aircraft that can be steered.
Airspace Hierarchy
Within the airspace classes, there is a hierarchy and, in the event of an overlap of airspace: Class A preempts Class B, Class B preempts Class C, Class C preempts Class D, Class D preempts Class E, and Class E preempts Class G.
Airspeed
The speed of an aircraft relative to its surrounding air mass. The unqualified term “airspeed” means one of the following: Indicated Airspeed, True Airspeed.
Airspeed indicator
A differential pressure gauge that measures the dynamic pressure of the air through which the aircraft is flying. Displays the craft’s airspeed, typically in knots, to the pilot.
Airstart
The starting of an aircraft engine while the aircraft is airborne, preceded by engine shutdown during training flights or by actual engine failure.
Airway
An airway is based on a centerline that extends from one navigation aid or intersection to another navigation aid (or through several navigation aids or intersections); used to establish a known route for en route procedures between terminal areas.
Airway Beacon
Used to mark airway segments in remote mountain areas. The light flashes Morse Code to identify the beacon site.
Airworthiness Certificate
A certificate issued by the FAA to all aircraft that have been proven to meet the minimum standards set down by the Code of Federal Regulations.
Airworthiness Directive
A regulatory notice sent out by the FAA to the registered owner of an aircraft informing the owner of a condition that prevents the aircraft from continuing to meet its conditions for airworthiness. Airworthiness Directives (AD notes) are to be complied with within the required time limit, and the fact of compliance, the date of compliance, and the method of compliance are recorded in the aircraft’s maintenance records.
ALD
Available Landing Distance
Alert
An actual situation involving two real safety logic tracks (aircraft/aircraft, aircraft/vehicle, or aircraft/other tangible object) that safety logic has predicted will result in an imminent collision, based upon the current set of Safety Logic parameters.
Alert Area
Airspace which may contain a high volume of pilot training activities or an unusual type of aerial activity, neither of which is hazardous to aircraft. Alert Areas are depicted on aeronautical charts for the information of nonparticipating pilots. All activities within an Alert Area are conducted in accordance with Federal Aviation Regulations, and pilots of participating aircraft as well as pilots transiting the area are equally responsible for collision avoidance.
Almanac data
Information the global positioning system (GPS) receiver can obtain from one satellite which describes the approximate orbital positioning of all satellites in the constellation. This information is necessary for the GPS receiver to know what satellites to look for in the sky at a given time.
Along-Track Distance (ATD)
The distance measured from a point-in-space by systems using area navigation reference capabilities that are not subject to slant range errors.
Alphanumeric Display
Letters and numerals used to show identification, altitude, beacon code, and other information concerning a target on a radar display.
Alternate Aerodrome [ICAO]
An aerodrome to which an aircraft may proceed when it becomes either impossible or inadvisable to proceed to or to land at the aerodrome of intended landing. Note: The aerodrome from which a flight departs may also be an en-route or a destination alternate aerodrome for the flight.
Altimeter
A flight instrument that indicates altitude by sensing pressure changes.
Altimeter setting
Station pressure (the barometric pressure at the location the reading is taken) which has been corrected for the height of the station above sea level.
Altitude
The height of a level, point, or object measured in feet Above Ground Level (AGL) or from Mean Sea Level (MSL).
Altitude (AGL)
The actual height above ground level (AGL) at which the aircraft is flying.
Altitude (MSL)
The actual height above mean sea level (MSL) at which the aircraft is flying.
Altitude Readout
An aircraft’s altitude, transmitted via the Mode C transponder feature, that is visually displayed in 100-foot increments on a radar scope having readout capability.
Altitude Restriction
An altitude or altitudes, stated in the order flown, which are to be maintained until reaching a specific point or time. Altitude restrictions may be issued by ATC due to traffic, terrain, or other airspace considerations.
Altitude Restrictions Are Canceled
Adherence to previously imposed altitude restrictions is no longer required during a climb or descent.
Amateur rocket
An unmanned rocket that:
(1) Is propelled by a motor or motors having a combined total impulse of 889,600 Newton-seconds (200,000 pound-seconds) or less; and
(2) Cannot reach an altitude greater than 150 kilometers (93.2 statute miles) above the earth’s surface.
Ambient pressure
The pressure in the area immediately surrounding the aircraft.
Ambient temperature
The temperature in the area immediately surrounding the aircraft.
AME
Aviation Medical Examiner.
Ammeter
An instrument installed in series with an electrical load used to measure the amount of current flowing through the load.
AMSL
Above Mean Sea Level
Aneroid
The sensitive component in an altimeter or barometer that measures the absolute pressure of the air. It is a sealed, flat capsule made of thin disks of corrugated metal soldered together and evacuated by pumping all of the air out of it.
Aneroid barometer
An instrument that measures the absolute pressure of the atmosphere by balancing the weight of the air above it against the spring action of the aneroid.
Angle of attack
The acute angle formed between the chord line of an airfoil and the direction of the air striking the airfoil.
Angle of incidence
The angle formed by the chord line of the wing and a line parallel to the longitudinal axis of the airplane.
Annual inspection
A complete inspection of an aircraft and engine, required by the Code of Federal Regulations, to be accomplished every 12 calendar months on all certificated aircraft. Only an A&P technician holding an Inspection Authorization can conduct an annual inspection.
ANP
Actual Navigation Performance
AP
Autopilot System
Approach Control Facility
A terminal ATC facility that provides approach control service in a terminal area.
Approach Control Service
Air traffic control service provided by an approach control facility for arriving and departing VFR/IFR aircraft and, on occasion, en route aircraft. At some airports not served by an approach control facility, the ARTCC provides limited approach control service.
Approach Sequence
The order in which aircraft are positioned while on approach or awaiting approach clearance.
Approach Speed
The recommended speed contained in aircraft manuals used by pilots when making an approach to landing. This speed will vary for different segments of an approach as well as for aircraft weight and configuration.
Approved
Unless used with reference to another person, approved by the FAA or any person to whom the FAA has delegated its authority in the matter concerned, or approved under the provisions of a bilateral agreement between the United States and a foreign country or jurisdiction.
Apron
A defined area on an airport or heliport intended to accommodate aircraft for purposes of loading or unloading passengers or cargo, refueling, parking, or maintenance. With regard to seaplanes, a ramp is used for access to the apron from the water.
Area Navigation (RNAV)
A method of navigation which permits aircraft operation on any desired flight path within the coverage of ground or space-based navigation aids or within the limits of the capability of self-contained aids, or a combination of these. Note: Area navigation includes performance-based navigation as well as other operations that do not meet the definition of performance-based navigation.
Area Navigation (RNAV) Approach Configuration
Includes Standard T, Modified T, Standard I, Terminal Arrival Area (TAA).
Area of operation
A phase of the practical test within the PTS.
ARENA
Areas Noted for Attention
ARFF
Aircraft Rescue and Fire Fighting
ARINC
An Acronym For Aeronautical Radio, Inc., A corporation largely owned by a group of airlines. ARINC is licensed by the FCC as an aeronautical station and contracted by the FAA to provide communications support for Air Traffic Control and Meteorological Services in portions of international airspace.
Armed Forces
The Army, Navy, Air Force, Marine Corps, and Coast Guard, including their regular and reserve components and members serving without component status.
ARO
Airport Reservations Office
ARPT
Airport
Arresting System
A safety device consisting of two major components, namely, engaging or catching devices and energy absorption devices for the purpose of arresting both tailhook and/or nontailhook-equipped aircraft. It is used to prevent aircraft from overrunning runways when the aircraft cannot be stopped after landing or during aborted takeoff. Arresting systems have various names; e.g., arresting gear, hook device, wire barrier cable.
Arrival Time
The time an aircraft touches down on arrival.
ARSA
Airport Radar Service Area
ARSR
Air Route Surveillance Radar. Air Route Traffic Control Center (ARTCC) radar used primarily to detect and display an aircraft´s position while en route between terminal areas. The ARSR enables controllers to provide radar air traffic control service when aircraft are within the ARSR coverage. In some instances, ARSR may enable an ARTCC to provide terminal radar services similar to but usually more limited than those provided by a radar approach control.
ARTCC
Air Route Traffic Control Center. A facility established to provide air traffic control service to aircraft operating on IFR flight plans within controlled airspace and principally during the en route phase of flight. When equipment capabilities and controller workload permit, certain advisory/assistance services may be provided to VFR aircraft. There are 20 ARTCCs in the continental U.S.
ARTS
Automated Radar Terminal System
ARTS IIIA
The Radar Tracking and Beacon Tracking Level (RT&BTL) of the modular, programmable automated radar terminal system. ARTS IIIA detects, tracks, and predicts primary as well as secondary radar-derived aircraft targets. This more sophisticated computer-driven system upgrades the existing ARTS III system by providing improved tracking, continuous data recording, and fail-soft capabilities.
ASDE
Airport Surface Detection Equipment.
ASDE-X
Airport Surface Detection Equipment - Model X
ASOS
Automated Surface Observing System
ASR
Airport Surveillance Radar. Approach control radar used to detect and display an aircraft´s position in the terminal area. ASR provides range and azimuth information but does not provide elevation data. Coverage of the ASR can extend up to 60 miles.
ASR APPROACH
Surveillance Approach
ASRS
Aviation Safety Reporting System
ATC
Air Traffic Control. A service operated by appropriate authority to promote the safe, orderly and expeditious flow of air traffic.
ATC Advises
Used to prefix a message of noncontrol information when it is relayed to an aircraft by other than an air traffic controller.
ATC Assigned Airspace
Airspace of defined vertical/lateral limits, assigned by ATC, for the purpose of providing air traffic segregation between the specified activities being conducted within the assigned airspace and other IFR air traffic.
ATC Clearance
Air Traffic Clearance.
ATC Clears
Used to prefix an ATC clearance when it is relayed to an aircraft by other than an air traffic controller.
ATC Instructions
Directives issued by air traffic control for the purpose of requiring a pilot to take specific actions; e.g., “Turn left heading two five zero,” “Go around,” “Clear the runway.”
ATC Requests
Used to prefix an ATC request when it is relayed to an aircraft by other than an air traffic controller.
ATCRBS
Air Traffic Control Radar Beacon System
ATCSCC
Air Traffic Control System Command Center
ATCT
Airport Traffic Control Tower. A terminal facility that uses air/ground communications, visual signaling, and other devices to provide ATC services to aircraft operating in the vicinity of an airport or on the movement area. Authorizes aircraft to land or takeoff at the airport controlled by the tower or to transit the Class D airspace area regardless of flight plan or weather conditions (IFR or VFR). A tower may also provide approach control services (radar or nonradar).
ATD
Along-Track Distance
ATIS
Automatic Terminal Information Service.
Atmospheric propagation delay
A bending of the electromagnetic (EM) wave from the satellite that creates an error in the GPS system.
ATS
Air Traffic Service.
Attitude indicator
The foundation for all instrument flight, this instrument reflects the airplane’s attitude in relation to the horizon.
Autokinesis
Nighttime visual illusion that a stationary light is moving, which becomes apparent after several seconds of staring at the light.
Automated Radar Terminal Systems (ARTS)
A generic term for several tracking systems included in the Terminal Automation Systems (TAS). ARTS plus a suffix roman numeral denotes a major modification to that system.
Automated Surface Observing System (ASOS)
A weather observing system that provides minute-by-minute weather observations such as temperature, dew point, wind, altimeter setting, visibility, sky condition, and precipitation. Some ASOS stations include a precipitation discriminator which can differentiate between liquid and frozen precipitation.
Automated Unicom
Provides completely automated weather, radio check capability and airport advisory information on an Automated UNICOM system. These systems offer a variety of features, typically selectable by microphone clicks, on the UNICOM frequency. Availability will be published in the Airport/Facility Directory and approach charts.
Automated Weather System
Any of the automated weather sensor platforms that collect weather data at airports and disseminate the weather information via radio and/or landline. The systems currently consist of the Automated Surface Observing System (ASOS), Automated Weather Sensor System (AWSS) and Automated Weather Observation System (AWOS).
Automatic Altitude Reporting
That function of a transponder which responds to Mode C interrogations by transmitting the aircraft’s altitude in 100-foot increments.
Automatic Dependent Surveillance-Broadcast (ADS-B)
A surveillance system in which an aircraft or vehicle to be detected is fitted with cooperative equipment in the form of a data link transmitter. The aircraft or vehicle periodically broadcasts its GPS-derived position and other information such as velocity over the data link, which is received by a ground-based transmitter/receiver (transceiver) for processing and display at an air traffic control facility.
Automatic Direction Finder
An aircraft radio navigation system which senses and indicates the direction to a L/MF nondirectional radio beacon (NDB) ground transmitter. Direction is indicated to the pilot as a magnetic bearing or as a relative bearing to the longitudinal axis of the aircraft depending on the type of indicator installed in the aircraft. In certain applications, such as military, ADF operations may be based on airborne and ground transmitters in the VHF/UHF frequency spectrum.
Automatic direction finder (ADF)
Electronic navigation equipment that operates in the low- and medium-frequency bands. Used in conjunction with the ground-based nondirectional beacon (NDB), the instrument displays the number of degrees clockwise from the nose of the aircraft to the station being received.
Automatic Flight Information Service (AFIS)
Alaska FSSs Only The continuous broadcast of recorded non-control information at airports in Alaska where a FSS provides local airport advisory service. The AFIS broadcast automates the repetitive transmission of essential but routine information such as weather, wind, altimeter, favored runway, breaking action, airport NOTAMs, and other applicable information. The information is continuously broadcast over a discrete VHF radio frequency (usually the ASOS/AWSS/AWOS frequency.
Automatic Terminal Information Service
The continuous broadcast of recorded noncontrol information in selected terminal areas. Its purpose is to improve controller effectiveness and to relieve frequency congestion by automating the repetitive transmission of essential but routine information; e.g., “Los Angeles information Alfa. One three zero zero Coordinated Universal Time. Weather, measured ceiling two thousand overcast, visibility three, haze, smoke, temperature seven one, dew point five seven, wind two five zero at five, altimeter two niner niner six. I-L-S Runway Two Five Left approach in use, Runway Two Five Right closed, advise you have Alfa.”
Autopilot
An automatic flight control system which keeps an aircraft in level flight or on a set course. Automatic pilots can be directed by the pilot, or they may be coupled to a radio navigation signal.
Available Landing Distance (ALD)
The portion of a runway available for landing and roll-out for aircraft cleared for LAHSO. This distance is measured from the landing threshold to the hold-short point.
Aviation medical examiner (AME)
A physician with training in aviation medicine designated by the Civil Aerospace Medical Institute (CAMI).
Aviation Weather Service
A service provided by the National Weather Service (NWS) and FAA which collects and disseminates pertinent weather information for pilots, aircraft operators, and ATC. Available aviation weather reports and forecasts are displayed at each NWS office and FAA FSS.
AWC
Aviation Weather Center
AWOS
Automated Weather Observing System.
AWSS
Automated Weather Sensor System
AWTT
Aviation Weather Technology Transfer
AWW
Severe Weather Forecast Alert
Axes of an aircraft
Three imaginary lines that pass through an aircraft’s center of gravity. The axes can be considered as imaginary axles around which the aircraft rotates. The three axes pass through the center of gravity at 90° angles to each other. The axis from nose to tail is the longitudinal axis (pitch), the axis that passes from wingtip to wingtip is the lateral axis (roll), and the axis that passes vertically through the center of gravity is the vertical axis (yaw).
Azimuth card
A card that may be set, gyroscopically controlled, or driven by a remote compass.
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