Aeronautical Terms beginning with A

A-RNAV

Advanced Area Navigation

A.C.

Alternating Current.

A.C.

Alternating current.

A/FD

Airport/Facility Directory—obsolete. Changed to Chart Supplement.

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

AAWU

Alaskan Aviation Weather Unit

Abbreviated IFR Flight Plans

An authorization by ATC requiring pilots to submit only that information needed for the purpose of ATC. It includes only a small portion of the usual IFR flight plan information. In certain instances, this may be only aircraft identification, location, and pilot request. Other information may be requested if needed by ATC for separation/control purposes. It is frequently used by aircraft which are airborne and desire an instrument approach or by aircraft which are on the ground and desire a climb to VFR-on-top.

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.

Abeam Fix

A fix, NAVAID, point, or object positioned approximately 90 degrees to the right or left of the aircraft track along a route of flight. 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 accuracy

The ability to determine present position in space independently, and is most often used by pilots.

Absolute Altitude

The vertical distance of an airplane above the terrain, or above ground level (AGL).

Absolute altitude

The actual distance between an aircraft and the terrain over which it is flying.

Absolute altitude

The actual distance between an aircraft and the terrain over which it is flying.

Absolute Ceiling

The altitude at which a climb is no longer possible.

Absolute instability

A state of a layer within the atmosphere in which the vertical distribution of temperature is such that an air parcel, if given an upward or downward push, wiII move away from its initial level without further outside force being applied.

Absolute pressure

Pressure measured from the reference of zero pressure, or a vacuum.

Absolute pressure

Pressure measured from the reference of zero pressure, or a vacuum.

Absolute temperature scale

Kelvin Temperature Scale. A temperature scale with zero degrees equal to the temperature at which all molecular motion ceases, i.e., absolute zero (0° K = -273° C); the Kelvin degree is identical to the Celsius degree; hence at standard sea level pressure, the melting point is 273° K and the boiling point 373° K.

Absolute vorticity

The rotation of the Earth imparts vorticity to the atmosphere; absolute vorticity is the combined vorticity due to this rotation and vorticity due to circulation relative to the Earth (relative vorticity).

Abstractions

Words that are general rather than specific. Aircraft is an abstraction; airplane is less abstract; jet is more specific; and jet airliner is still more specific.

AC

Advisory Circular

AC

Advisory Circular

AC, A/C or ACFT

Aircraft

ACAR

Aircraft Communications Addressing and Reporting System

ACARS

Aircraft Communications Addressing and Reporting System

ACAS

Airborne Collision Avoidance System

Accelerate-Go Distance

The distance required to accelerate to V1 with all engines at takeoff power, experience an engine failure at V1, and continue the takeoff on the remaining engine(s). The runway required includes the distance required to climb to 35 feet by which time V2 speed must be attained.

Accelerate-Stop Distance

The distance required to accelerate to V1 with all engines at takeoff power, experience an engine failure at V1, and abort the takeoff and bring the airplane to a stop using braking action only (use of thrust reversing is not considered).

Accelerate-Stop Distance Available

The runway plus stopway length declared available and suitable for the acceleration and deceleration of an airplane aborting a takeoff.

Accelerate-Stop Distance Available (ASDA)

The runway plus stopway length declared available and suitable for the acceleration and deceleration of an airplane aborting a takeoff.

Accelerate-Stop Distance Available [ICAO]

The length of the take-off run available plus the length of the stopway if provided.

Acceleration

Force involved in overcoming inertia, and which may be defined as a change in velocity per unit of time.

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.

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.

Accelerometer

A part of an inertial navigation system (INS) that accurately measures the force of acceleration in one direction.

Accelerometer

A part of an inertial navigation system (INS) that accurately measures the force of acceleration in one direction.

Accessories

Components that are used with an engine, but are not a part of the engine itself. Units such as magnetos, carburetors, generators, and fuel pumps are commonly installed engine accessories.

Acknowledge

Let me know that you have received my message.

ACL

Aircraft List

ACLS

Automatic Carrier Landing System

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.

Actual Calculated Landing Time

ACLT is a flight’s frozen calculated landing time. An actual time determined at freeze calculated landing time (FCLT) or meter list display interval (MLDI) for the adapted vertex for each arrival aircraft based upon runway configuration, airport acceptance rate, airport arrival delay period, and other metered arrival aircraft. This time is either the vertex time of arrival (VTA) of the aircraft or the tentative calculated landing time (TCLT)/ACLT of the previous aircraft plus the arrival aircraft interval (AAI), whichever is later. This time will not be updated in response to the aircraft’s progress.

Actual Navigation Performance (ANP)

A measure of the current estimated navigational performance. Also referred to as Estimated Position Error (EPE).

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.

ADF

Automatic Direction Finder.

ADI

Attitude Director Indicator.

ADI

Attitude Director Indicator.

Adiabatic cooling

A process of cooling the air through expansion. For example, as air moves up slope it expands with the reduction of atmospheric pressure and cools as it expands.

Adiabatic Cooling

A process by which a parcel of air cools. When a parcel of air is lifted, pressure is reduced due to the elevation increase. This reduction in pressure causes the parcel of air to expand in volume and, in turn, the parcel cools to maintain an energy balance because no energy is added to the parcel.

Adiabatic heating

A process of heating dry air through compression. For example, as air moves down a slope it is compressed, which results in an increase in temperature.

Adiabatic process

The process by which fixed relationships are maintained during changes in temperature, volume, and pressure in a body of air without heat being added or removed from the body.

ADIZ

Air Defense Identification Zone

Adjustable Stabilizer

A stabilizer that can be adjusted in flight to trim the airplane, thereby allowing the airplane to fly hands-off at any given airspeed.

Adjustable-pitch propeller

A propeller with blades whose pitch can be adjusted on the ground with the engine not running, but which cannot be adjusted in flight. Also referred to as a ground adjustable propeller. Sometimes also used to refer to constant-speed propellers that are adjustable in flight.

ADM

Aeronautical Decision-Making.

ADM

Aeronautical Decision-Making

Administrator

The Federal Aviation Administrator or any person to whom he has delegated his authority in the matter concerned.

Automatic Dependent Surveillance

ADS-B

Automatic Dependent Surveillance-Broadcast.

ADSB

Automatic Dependent Surveillance Broadcast.

Advection

The horizontal transport of air or atmospheric properties. In meteorology, sometimes referred to as the horizontal component of convection.

Advection fog

Fog resulting from the transport of warm, humid air over a cold surface.

Adverse Loaded CG Check

A weight and balance check to determine that no condition of legal loading of an aircraft can move the CG outside of its allowable limits.

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.

Adverse yaw

A flight condition at the beginning of a turn in which the nose of the aircraft starts to move in the direction opposite the direction the turn is being made, caused by the induced drag produced by the downward-deflected aileron holding back the wing as it begins to rise.

Adverse yaw

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

AER

Approach End of Runway

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.

Aerodynamic Ceiling

The point (altitude) at which, as the indicated airspeed decreases with altitude, it progressively merges with the low speed buffet boundary where pre-stall buffet occurs for the airplane at a load factor of 1.0 G.

Aerodynamic coefficients

Non-dimensional coefficients for aerodynamic forces and moments.

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.

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.

Aeronautical decision-making (ADM)

A systematic approach to the mental process used by pilots to consistently determine the best course of action in response to a given set of circumstances.

Aeronautical decision-making (ADM)

A systematic approach to the mental process used by aircraft pilots to consistently determine the best course of action in response to a given set of circumstances.

Aeronautical decision-making (ADM)

A systematic approach to the mental process used by pilots to consistently determine the best course of action in response to a given set of circumstances.

AFCS

Automatic Flight Control System

Affective domain

A grouping of levels of learning associated with a person’s attitudes, personal beliefs, and values which range from receiving through responding, valuing, and organization to characterization.

Affirmative

Yes.

AFIS

Automatic Flight Information Service

AFM

Airplane Flight Manual or Aircraft Flight Manual

AFM

Airplane Flight Manual.

AFM

Aircraft Flight Manual

AFP

An AFP is a traffic management (TM) process administered by the ATCSCC. Aircraft are assigned specific airspace arrival slots utilizing flight schedule monitor (FSM) to manage capacity and demand for a specific area of the National Airspace System (NAS). AFPs support the TM mission and mitigate the effects of en route constraints. Please see the AFP Advisory circular for more details.

AFSS

Automated Flight Service Station

AFSS

Automated Flight Service Station

AGL

Above Ground Level

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.

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.

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

AIM

Aeronautical Information Manual

AIP

Aeronautical Information Publication

Air carrier

A person who undertakes directly by lease, or other arrangement, to engage in air transportation.

Air Carrier District Office

An FAA field office serving an assigned geographical area, staffed with Flight Standards personnel serving the aviation industry and the general public on matters related to the certification and operation of scheduled air carriers and other large aircraft operations.

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 data computer (ADC)

An aircraft computer that receives and processes pitot pressure, static pressure, and temperature to calculate very precise altitude, indicated airspeed, true airspeed, and air temperature.

Air data computer (ADC)

An aircraft computer that receives and processes pitot pressure, static pressure, and temperature to calculate very precise altitude, indicated airspeed, true airspeed, and air temperature.

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 density

The mass density of the air in terms of weight per unit volume.

Air mass

In meteorology, an extensive body of air within which the conditions of temperature and moisture in a horizontal plane are essentially uniform.

Air mass classification

A system used to identify and to characterize the different air masses according to a basic scheme. The system most commonly used classifies air masses primarily according to the thermal properties of their source regions: “tropical” (T); “polar” (P); and “Arctic” or “Antarctic” (A). They are further classified according to moisture characteristics as “continental” (c) or “maritime” (m).

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 parcel

A. small volume of air, small enough to contain uniform distribution of its meteorological properties, and large enough to remain relatively self-contained and respond to all meteorological processes. No specific dimensions have been defined, however, the order of magnitude of 1 cubic foot has been suggested.

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 surveillance radar (ARSR)

Air route traffic control center (ARTCC) radar used primarily to detect and display an aircrafts position while en route between terminal areas.

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)

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

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 Start

The act or instance of starting an aircraft’s engine while in flight, especially a jet engine after flameout.

Air Taxi

Used to describe a helicopter/VTOL aircraft movement conducted above the surface but normally not above 100 feet AGL. The aircraft may proceed either via hover taxi or flight at speeds more than 20 knots. The pilot is solely responsible for selecting a safe airspeed/altitude for the operation being conducted.

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 (ATC)

A service provided by the FAA 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 radar beacon system (ATCRBS).

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)

Air traffic service is an ICAO generic term meaning variously, flight information service, alerting service, air traffic advisory service, air traffic control service (area control service, approach control service, or aerodrome control service).

Air Traffic Service (ATS) route

A specified route designated for channeling the flow of traffic as necessary for the provision of air traffic services. The term “ATS route” refers to a variety of airways, including jet routes, area navigation (RNAV) routes, and arrival and departure routes. An ATS route is defined by route specifications, which may include:
(1) An ATS route designator;
(2) The path to or from significant points;
(3) Distance between significant points;
(4) Reporting requirements; and
(5) The lowest safe altitude determined by the appropriate authority.

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

A device that is used, or intended to be used, for flight.

Aircraft altitude

The actual height above sea level at which the aircraft is flying.

Aircraft Approach Category

A grouping of aircraft based on a speed of 1.3 times the stall speed in the landing configuration at maximum gross landing weight. An aircraft must fit in only one category. If it is necessary to maneuver at speeds in excess of the upper limit of a speed range for a category, the minimums for the category for that speed must be used. For example, an aircraft which falls in Category A, but is circling to land at a speed in excess of 91 knots, must use the approach Category B minimums when circling to land. The categories are A-E.

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.”

Aircraft engine

An engine that is used or intended to be used for propelling aircraft. It includes turbosuperchargers, appurtenances, and accessories necessary for its functioning, but does not include propellers.

Aircraft Logbooks

Journals containing a record of total operating time, repairs, alterations or inspections performed, and all Airworthiness Directive (AD) notes complied with. A maintenance logbook should be kept for the airframe, each engine, and each propeller.

Aircraft Specifications

Documentation containing the pertinent specifications for aircraft certificated under the CARs.

Airfoil

An airfoil is 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.

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.

Airframe

The fuselage, booms, nacelles, cowlings, fairings, airfoil surfaces (including rotors but excluding propellers and rotating airfoils of engines), and landing gear of an aircraft and their accessories and controls.

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.

Airmanship Skills

The skills of coordination, timing, control touch, and speed sense in addition to the motor skills required to fly an aircraft.

Airmen’s Meteorological Information

AIRMET.

Airmen’s Meteorological Information (AIRMET)

In-flight weather advisories concerning weather phenomena of operational interest to all pilots and especially to pilots of aircraft not approved for flight in icing conditions. An AIRMET concerns weather of lesser severity than that covered by an advisory of significant meteorological information (SIGMET) or a convective SIGMET. AIRMETs may include advisories of moderate icing.

AIRMET

Inflight weather advisory issued as an amendment to the area forecast, concerning weather phenomena of operational interest to all aircraft and that is potentially hazardous to aircraft with limited capability due to lack of equipment, instrumentation, or pilot qualifications.

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

An engine-driven, fixed-wing aircraft heavier than air that is supported in flight by the dynamic reaction of 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 Flight Manual (AFM)

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.

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 Arrival Rate (AAR)

A dynamic input parameter specifying the number of arriving aircraft which an airport or airspace can accept from the ARTCC per hour. The AAR is used to calculate the desired interval between successive arrival aircraft.

Airport Departure Rate (ADR)

A dynamic parameter specifying the number of aircraft which can depart an airport and the airspace can accept per hour.

Airport Diagram

A full-page depiction of the airport that includes the same features of the airport sketch plus additional details such as taxiway identifiers, airport latitude and longitude, and building identification. Airport diagrams are located in the U.S. Terminal Procedures booklet following the instrument approach charts for a particular airport.

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 Reservation Office

Office responsible for monitoring the operation of slot controlled airports. It receives and processes requests for unscheduled operations at slot controlled airports.

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 Sketch

Depicts the runways and their length, width, and slope, the touchdown zone elevation, the lighting system installed on the end of the runway, and taxiways. Airport sketches are located on the lower left or right portion of the instrument approach chart.

Airport surface detection equipment (ASDE)

Radar equipment specifically designed to detect all principal features and traffic on the surface of an airport, presenting the entire image on the control tower console; used to augment visual observation by tower personnel of aircraft and/or vehicular movements on runways and taxiways.

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 surveillance radar (ASR)

Approach control radar used to detect and display an aircrafts position in the terminal area.

Airport surveillance radar approach

An instrument approach in which ATC issues instructions for pilot compliance based on aircraft position in relation to the final approach course and the distance from the end of the runway as displayed on the controllers radar scope.

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)

Airport/Facility Directory (A/FD)

Regional booklets published by the National Aeronautical Charting Office. Title changed to Chart Supplement. (NACO) that provide textual information about all airports, both VFR and IFR. The A/FD includes runway length and width, runway surface, load bearing capacity, runway slope, airport services, and hazards such as birds and reduced visibility.

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 crafts airspeed, typically in knots, to the pilot.

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

Airway Beacon

Used to mark airway segments in remote mountain areas. The light flashes Morse Code to identify the beacon site.

Airworthiness

A condition in which the aircraft conforms to its type certificated design including supplemental type certificates, and field approved alterations. The aircraft must also be in a condition for safe flight as determined by annual, 100 hour, preflight and any other required inspections.

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 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) must be complied with within the required time limit, and the fact of compliance, the date of compliance, and the method of compliance must be recorded in the aircraft’s maintenance records.

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.

AIS

Airmen’s Information System

ALAR

Approach and Landing Accident Reduction

Albedo

The ratio of the amount of electromagnetic radiation reflected by a body to the amount incident upon it, commonly expressed in percentage; in meteorology, usually used in reference to insolation (solar radiation); i.e., the albedo of wet sand is 9, meaning that about 9% of the incident insolation is reflected; albedoes of other surfaces range upward to 80-85 for fresh snow cover; average albedo for the earth and its atmosphere has been calculated to range from 35 to 43.

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

An area in which there is a high volume of pilot training or an unusual type of aeronautical activity.

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.

Almanac data

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.

Alpha Mode Of Operation

The operation of a turboprop engine that includes all of the flight operations, from takeoff to landing. Alpha operation is typically between 95 percent to 100 percent of the engine operating speed.

Alphanumeric Display

Letters and numerals used to show identification, altitude, beacon code, and other information concerning a target on a radar display.

ALS

Approach Lighting System.

ALSF-1

Approach Light System With Sequenced Flashing Lights In ILS CAT-I Configuration

ALSF-2

Approach Light System With Sequenced Flashing Lights In ILS Cat-II Configuration. The ALSF-2 May Operate As An SSALR When Weather Conditions Permit

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.

Alternate Air

A device which opens, either automatically or manually, to allow induction airflow to continue should the primary induction air opening become blocked.

Alternate airport

An airport designated in an IFR flight plan, providing a suitable destination if a landing at the intended airport becomes inadvisable.

Alternate Static Source

A manual port that when opened allows the pitot static instruments to sense static pressure from an alternate location should the primary static port become blocked.

Alternate static source valve

A valve in the instrument static air system that supplies reference air pressure to the altimeter, airspeed indicator, and vertical speed indicator if the normal static pickup should become clogged or iced over.

Alternate static source valve

Alternator/Generator

A device that uses engine power to generate electrical power.

Altimeter

A flight instrument that indicates altitude by sensing pressure changes.

Altimeter

An instrument which determines the altitude of an object with respect to a fixed level. A pressure altimeter.

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.

Altimeter setting

The value to which the scale of a pressure altimeter is set so as to read true altitude at field elevation.

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.

Altimeter setting indicator

A precision aneroid barometer calibrated to indicate directly the altimeter setting.

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 Chamber

A device that simulates high altitude conditions by reducing the interior pressure. The occupants will suffer from the same physiological conditions as flight at high altitude in an unpressurized aircraft.

Altitude Engine

A reciprocating aircraft engine having a rated takeoff power that is producible from sea level to an established higher altitude.

Altitude engine

A reciprocating aircraft engine having a rated takeoff power that is producible from sea level to an established higher altitude.

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.

Altocumulus

White or gray layers or patches of cloud, often with a waved appearance; cloud elements appear as rounded masses or rolls; composed mostly of liquid water droplets which may be supercooled; may contain ice crystals at subfreezing temperatures.

Altocumulus castellanus

A species of middle cloud of which at least a fraction of its upper part presents some vertically developed, cumuliform protuberances (some of which are taller than they are wide, as castles) and which give the cloud a crenelated or turreted appearance; especially evident when seen from the side; elements usually have a common base arranged in lines. This cloud indicates instability and turbulence at the altitudes of occurrence.

AMASS

Airport Movement Area Safety System

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.

AME

Aviation Medical Examiner.

Amendment status

The circulation date and revision number of an instrument approach procedure, printed above the procedure identification.

Ammeter

An instrument installed in series with an electrical load used to measure the amount of current flowing through the load.

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

Anemometer

An instrument for measuring wind speed.

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

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.

Aneroid barometer

A barometer which operates on the principle of having changing atmospheric pressure bend a metallic surface which, in turn, moves a pointer across a scale graduated in units of pressure.

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.

Angel

In radar meteorology, an echo caused by physical phenomena not discernible to the eye; they have been observed when abnormally strong temperature and/or moisture gradients were known to exist; sometimes attributed to insects or birds flying in the radar beam.

Angle Of Attack

The acute angle between the chord line of the airfoil and the direction of the relative wind.

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 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.

Angle of incidence

The angle formed by the chord line of the wing and a line parallel to the longitudinal axis of the airplane.

Anhedral

A downward slant from root to tip of an aircraft’s wing or horizontal tail surface.

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.

Annual inspection

Anomalous propagation (sometimes called A P )

In radar meteorology, the greater than normal bending of the radar beam such that echoes are received from ground targets at distances greater than normal ground clutter.

ANP

Actual Navigation Performance

ANP

Actual Navigation Performance

ANR

Advanced Navigation Route

Anti-ice

Preventing the accumulation of ice on an aircraft structure via a system designed for that purpose.

Anti-ice

Preventing the accumulation of ice on an aircraft structure via a system designed for that purpose.

Anti-Icing

The prevention of the formation of ice on a surface. Ice may be prevented by using heat or by covering the surface with a chemical that prevents water from reaching the surface. Anti-icing should not be confused with deicing, which is the removal of ice after it has formed on the surface.

Anticyclone

An area of high atmospheric pressure which has a closed circulation that is anticyclonic, i.e., as viewed from above, the circulation is clockwise in the Northern Hemisphere, counterclockwise in the Southern Hemisphere, undefined at the Equator.

Antiservo tab

An adjustable tab attached to the trailing edge of a stabilator that moves in the same direction as the primary control. It is used to make the stabilator less sensitive.

Anvil cloud

Popular name given to the top portion of a cumulonimbus cloud having an anvil-like form.

Anxiety

Mental discomfort that arises from the fear of anything, real or imagined. May have a potent effect on actions and the ability to learn from perceptions.

AOA

Airport Operating Area

AOCC

Airline Operations Control Center

AP

Autopilot System

AP

Autopilot System

APC

Auxiliary Performance Computer

APOB

A sounding made by an aircraft.

Appliance

Any instrument, mechanism, equipment, part, apparatus, appurtenance, or accessory, including communications equipment, that is used or intended to be used in operating or controlling an aircraft in flight, is installed in or attached to the aircraft, and is not part of an airframe, engine, or propeller.

Application

A basic level of learning at which the student puts something to use that has been learned and understood.

Application step

The third step of the teaching process, where the student performs the procedure or demonstrates the knowledge required in the lesson. In the telling-and-doing technique of flight instruction, this step consists of the student doing the procedure while explaining it.

Approach Clearance

Authorization by ATC for a pilot to conduct an instrument approach. The type of instrument approach for which a clearance and other pertinent information is provided in the approach clearance when required.

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 End of Runway (AER)

The first portion of the runway available for landing. If the runway threshold is displaced, use the displaced threshold latitude/longitude as the AER.

Approach Fix

From a database coding standpoint, an approach fix is considered to be an identifiable point in space from the intermediate fix (IF) inbound. A fix located between the initial approach fix (IAF) and the IF is considered to be associated with the approach transition or feeder route.

Approach Gate

An imaginary point used by ATC to vector aircraft to the final approach course. The approach gate is established along the final approach course 1 NM from the final approach fix (FAF) on the side away from the airport and is located no closer than 5 NM from the landing threshold.

Approach Light 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/her final approach for landing. Condenser-Discharge Sequential Flashing Lights/Sequenced Flashing Lights may be installed in conjunction with the ALS at some airports. Types of Approach Light Systems are: ALSF-1, ALSF-2, SSALF, SSALR, MALSF, MALSR, LDIN, RAIL, ODALS.

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.

Appropriate Authority

A. Regarding flight over the high seas: the relevant authority is the State of Registry.
B. Regarding flight over other than the high seas: the relevant authority is the State having sovereignty over the territory being overflown.

Appropriate Obstacle Clearance Minimum Altitude

Any of the following: Minimum En Route IFR Altitude, Minimum IFR Altitude, Minimum Obstruction Clearance Altitude, Minimum Vectoring Altitude.

Appropriate Terrain Clearance Minimum Altitude

Any of the following: Minimum En Route IFR Altitude, Minimum IFR Altitude, Minimum Obstruction Clearance Altitude, Minimum Vectoring Altitude.

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.

Approved Type Certificate

A certificate of approval issued by the FAA for the design of an aircraft, engine, or propeller.

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.

APU

Auxiliary Power Unit.

APV

Approach With Vertical Guidance

Arc

The track over the ground of an aircraft flying at a constant distance from a navigational aid by reference to distance measuring equipment (DME).

Arctic air

An air mass with characteristics developed mostly in winter over Arctic surfaces of ice and snow. Arctic air extends to great heights, and the surface temperatures are basically, but not always, lower than those of polar air.

Arctic front

The surface of discontinuity between very cold (Arctic) air flowing directly from the Arctic region and another less cold and, consequently, less dense air mass.

Area chart

Part of the low-altitude en route chart series, this chart furnishes terminal data at a larger scale for congested areas.

Area chart

Part of the low-altitude en route chart series, this chart furnishes terminal data at a larger scale for congested areas.

Area forecast (FA)

A report that gives a picture of clouds, general weather conditions, and visual meteorological conditions (VMC) expected over a large area encompassing several states. (Discontinued, replaced by Graphical Forecasts for Aviation)

Area navigation (RNAV)

Allows a pilot to fly a selected course to a predetermined point without the need to overfly ground-based navigation facilities, by using waypoints.

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.

Arm

(GAMA) The horizontal distance from the reference datum to the center of gravity (CG) of an item. The algebraic sign is plus (+) if measured aft of the datum or to the right side of the center line when considering a lateral calculation. The algebraic sign is minus (-) if measured forward of the datum or the left side of the center line when considering a lateral calculation.

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 Aircraft Interval

An internally generated program in hundredths of minutes based upon the AAR. AAI is the desired optimum interval between successive arrival aircraft over the vertex.

Arrival Center

The ARTCC having jurisdiction for the impacted airport.

Arrival Delay

A parameter which specifies a period of time in which no aircraft will be metered for arrival at the specified airport.

Arrival Time

The time an aircraft touches down on arrival.

ARSA

Airport Radar Service Area

ARSR

Air Route Surveillance Radar.

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.

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

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.

ASDA

Accelerate-Stop Distance Available

ASDAR

Aircraft To Satellite Data Relay

ASDE

Airport Surface Detection Equipment.

ASDE

Airport Surface Detection Equipment.

ASDE-3

Airport Surface Detection Equipment-3

ASDE-X

Airport Surface Detection Equipment-X

ASDE-X

Airport Surface Detection Equipment - Model X

ASOS

Automated Surface Observing Station.

ASOS

Automated Surface Observing System

ASOS

Automated Surface Observing System.

Aspect ratio

Span of a wing divided by its average chord.

ASR

Airport Surveillance Radar.

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

Astronomical twilight

The period of time before sunrise and after sunset when the sun is not more than 18° below the horizon.

Asymmetric thrust

Also known as P-factor. A tendency for an aircraft to yaw to the left due to the descending propeller blade on the right producing more thrust than the ascending blade on the left. This occurs when the aircraft’s longitudinal axis is in a climbing attitude in relation to the relative wind.The P-factor would be to the right if the aircraft had a counterclockwise rotating propeller.

ATC

Air Traffic Control.

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 Preferred Route Notification

URET notification to the appropriate controller of the need to determine if an ATC preferred route needs to be applied, based on destination airport.

ATC Requests

Used to prefix an ATC request when it is relayed to an aircraft by other than an air traffic controller.

ATC-TFM

Air Traffic Control Traffic Flow Management

ATCRBS

Air Traffic Control Radar Beacon System.

ATCRBS

Air Traffic Control Radar Beacon System

ATCSCC

Air Traffic Control System Command Center

ATCSCC

Air Traffic Control System Command Center

ATCT

Airport Traffic Control Tower

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

ATD

Along-Track Distance

ATIS

Automatic Terminal Information Service.

ATIS

Automatic Terminal Information Service

ATIS

Automatic Terminal Information Service.

ATM

Air Traffic Management

Atmosphere

The mass of air surrounding the Earth.

Atmospheric pressure (also called barometric pressure)

The pressure exerted by the atmosphere as a consequence of gravitational attraction exerted upon the “column” of air lying directly above the point in question.

Atmospheric propagation delay

A bending of the electromagnetic (EM) wave from the satellite that creates an error in the GPS system.

Atmospheric propagation delay

A bending of the electromagnetic (EM) wave from the satellite that creates an error in the GPS system.

Atmospherics

Disturbing effects produced in radio receiving apparatus by atmospheric electrical phenomena such as an electrical storm. Static.

ATS

Air Traffic Service

ATS

Air Traffic Service.

ATT

Attitude Retention System

Attenuation

In radar meteorology, any process which reduces power density in radar signals.

Attitude

The position of an aircraft as determined by the relationship of its axes and a reference, usually the earth’s horizon.

Attitude

A personal motivational predisposition to respond to persons, situations, or events in a given manner that can, nevertheless, be changed or modified through training as a sort of mental shortcut to decision-making.

Attitude and heading reference system (AHRS)

A system composed of three-axis sensors that provide heading, attitude, and yaw information for aircraft. AHRS are designed to replace traditional mechanical gyroscopic flight instruments and provide superior reliability and accuracy.

Attitude and heading reference systems (AHRS)

System composed of three-axis sensors that provide heading, attitude, and yaw information for aircraft. AHRS are designed to replace traditional mechanical gyroscopic flight instruments and provide superior reliability and accuracy.

Attitude director indicator (ADI)

An aircraft attitude indicator that incorporates flight command bars to provide pitch and roll commands.

Attitude director indicator (ADI)

An aircraft attitude indicator that incorporates flight command bars to provide pitch and roll commands.

Attitude Indicator

An instrument which uses an artificial horizon and miniature airplane to depict the position of the airplane in relation to the true horizon. The attitude indicator senses roll pitch, which is the up and down as well as movement of the airplane’s nose.

Attitude indicator

The foundation for all instrument flight, this instrument reflects the airplanes attitude in relation to the horizon.

Attitude indicator

The foundation for all instrument flight, this instrument reflects the airplane’s attitude in relation to the horizon.

Attitude instrument flying

Controlling the aircraft by reference to the instruments rather than by outside visual cues.

Attitude management

The ability to recognize one’s own hazardous attitudes and the willingness to modify them as

Aurora

A luminous, radiant emission over middle and high latitudes confined to the thin air of high altitudes and centered over the earth’s magnetic poles. Called “aurora borealis” (northern lights) or “aurora australis” according to its occurrence in the Northern or Southern Hemisphere, respectively.

Authentic assessment

An assessment in which the student is asked to perform real-world tasks, and demonstrate a meaningful application of skills and competencies.

Autokinesis

This is caused by staring at a single point of light against a dark background for more than a few seconds. After a few moments, the light appears to move on its own.

Autokinesis

Nighttime visual illusion that a stationary light is moving, which becomes apparent after several seconds of staring at the light.

Autokinesis

Nighttime visual illusion that a stationary light is moving, which becomes apparent after several seconds of staring at the light.

Autoland Approach

An autoland approach is a precision instrument approach to touchdown and, in some cases, through the landing rollout. An autoland approach is performed by the aircraft autopilot which is receiving position information and/or steering commands from onboard navigation equipment. Note: Autoland and coupled approaches are flown in VFR and IFR. It is common for carriers to require their crews to fly coupled approaches and autoland approaches (if certified) when the weather conditions are less than approximately 4,000 RVR.

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 Station (ASOS)

Weather reporting system which provides surface observations every minute via digitized voice broadcasts and printed reports.

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 Surface Observing System (ASOS)

Weather reporting system which provides surface observations every minute via digitized voice broadcasts and printed reports.

Automated Surface Observing System (ASOS)

A suite of sensors that measure, collect, and disseminate weather data to help meteorologists, pilots, and flight dispatchers prepare and monitor weather forecasts, plan flight routes, and provide necessary information for correct takeoffs and landings. There are many differences between an ASOS and an All Weather Operations Specialist (AWOS) (see subparagraph 1-3d). It is important for pilots to understand the strengths and limitations of the various configurations. The ASOS is comprised of a standardized suite of weather sensors and is a product of a National Weather Service (NWS), Department of Defense (DOD), and FAA joint venture. One of ASOS’s most important features is its ability to detect precipitation, including intensity of rain, snow, and freezing rain. One current ASOS limitation is its inability to simultaneously detect and report freezing drizzle, ice pellets, or any other freezing precipitation without human augmentation when other forms of precipitation are present. A detailed description of ASOS’s capabilities can be found at the NWS ASOS homepage: http://www.nws.noaa.gov/asos/index.html.

Automated Surface Observing System (ASOS)/Automated Weather Sens

The ASOS/AWSS is the primary surface weather observing system of the U.S.

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 Observation System (AWOS)

A suite of weather sensors that are procured by the FAA or purchased by individuals, groups, airports, etc. It is important to note that the absence of reported precipitation does not mean that such conditions do not exist. The AWOS may not be configured to report this information or have precipitation reporting capability. A detailed description of AWOS’s capabilities can be found in the AIM.

Automated Weather Observing System (AWOS)

A suite of sensors which measure, collect, and disseminate weather data. AWOS stations provide a minute-by minute update of weather parameters such as wind speed and direction, temperature and dew point, visibility, cloud heights and types, precipitation, and barometric pressure. A variety of AWOS system types are available (from AWOS 1 to AWOS 3), each of which includes a different sensor array.

Automated Weather Observing System (AWOS)

Automated weather reporting system consisting of various sensors, a processor, a computer-generated voice subsystem, and a transmitter to broadcast weather data.

Automated Weather Sensor System (AWSS)

The AWSS is part of the Aviation Surface Weather Observation Network suite of programs and provides pilots and other users with weather information through the Automated Surface Observing System. The AWSS sensor suite automatically collects, measures, processes, and broadcasts surface weather data.

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).

Automated Weather System

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 that continuously broadcasts GPS position information, aircraft identification, altitude, velocity vector, and direction to all other aircraft and air traffic control facilities within a specific area. Automatic dependent surveillance-broadcast (ADS-B) information will be displayed in the cockpit via a cockpit display of traffic information (CDTI) unit, providing the pilot with greater situational awareness. ADS-B transmissions will also provide controllers with a more complete picture of traffic and will update that information more frequently than other surveillance equipment.

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 direction finder (ADF)

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.”

Automatic Terminal Information Service (ATIS)

A recorded broadcast available at most airports with an operating control tower that includes crucial information about runways and instrument approaches in use, specific outages, and current weather conditions, including visibility.

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.

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.

Autorotation

A rotorcraft flight condition in which the lifting rotor is driven entirely by action of the air when the rotorcraft is in motion.

Autorotative Landing/Touchdown Autorotation

Used by a pilot to indicate that the landing will be made without applying power to the rotor.

Auxiliary rotor

A rotor that serves either to counteract the effect of the main rotor torque on a rotorcraft or to maneuver the rotorcraft about one or more of its three principal axes.

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 medical examiner (AME)

A physician with training in aviation medicine designated by the Civil Aerospace Medical Institute (CAMI).

Aviation Routine Weather Report (METAR)

Observation of current surface weather reported in a standard international format.

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.

Aviation Weather Service Program

Aviation weather service provided by the NWS and the FAA that collects and disseminates pertinent weather information for pilots, aircraft operators, and air traffic control (ATC).

AVN

Office of Aviation System Standards

AWC

Aviation Weather Center

AWOS

Automated Weather Observing System.

AWOS

Automated Weather Observing System

AWOS

Automated Weather Observing System.

AWSS

Automated Weather Sensor 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 turns. 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, the axis that passes from wingtip to wingtip is the lateral axis, and the axis that passes vertically through the center of gravity is the vertical axis.

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).

Axial Flow Compressor

A type of compressor used in a turbine engine in which the airflow through the compressor is essentially linear. An axial-flow compressor is made up of several stages of alternate rotors and stators. The compressor ratio is determined by the decrease in area of the succeeding stages.

Azimuth card

A card that may be set, gyroscopically controlled, or driven by a remote compass.

Azimuth card

A card that may be set, gyroscopically controlled, or driven by a remote compass.

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