Aeronautical Terms

100-hour inspection

An inspection identical in scope to an annual inspection. Conducted every 100 hours of flight on aircraft of under 12,500 pounds that are used to carry passengers for hire.

14 CFR

Title 14 of the Code of Federal Regulations.

14 CFR part 121

The Federal regulations governing domestic, flag, and supplemental operations.

14 CFR part 135

The Federal regulations governing Commuter and On-Demand Operations.

14 CFR part 43

The Federal regulations governing Maintenance, Preventive Maintenance, Rebuilding, And Alteration

14 CFR Part 61

The Federal regulations governing Pilots, Flight Instructors, And Ground Instructors.

14 CFR Part 91

The Federal regulations governing General Operating And Flight Rules

14 CFR–Title 14 of the Code of Federal Regulations

Includes the federal aviation regulations governing the operation of aircraft, airways, and airmen.

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.

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.

Back-Taxi

A term used by air traffic controllers to taxi an aircraft on the runway opposite to the traffic flow. The aircraft may be instructed to back-taxi to the beginning of the runway or at some point before reaching the runway end for the purpose of departure or to exit the runway.

Balked Landing

A go-around.

Balloon

A lighter-than-air aircraft that is not engine driven, and that sustains flight through the use of either gas buoyancy or an airborne heater.

Barometric scale

A scale on the dial of an altimeter to which the pilot sets the barometric pressure level from which the altitude shown by the pointers is measured.

Base Leg

A flight path at right angles to the landing runway off its approach end. The base leg normally extends from the downwind leg to the intersection of the extended runway centerline.

Basic empty weight (GAMA)

Basic empty weight includes the standard empty weight plus optional and special equipment that has been installed.

Basic Radar Service

These services are provided for VFR aircraft by all commissioned terminal radar facilities. Basic radar service includes safety alerts, traffic advisories, limited radar vectoring when requested by the pilot, and sequencing at locations where procedures have been established for this purpose and/or when covered by a letter of agreement. The purpose of this service is to adjust the flow of arriving IFR and VFR aircraft into the traffic pattern in a safe and orderly manner and to provide traffic advisories to departing VFR aircraft.

Beacon

Aeronautical Beacon.

Bearing

The horizontal direction to or from any point, usually measured clockwise from true north, magnetic north, or some other reference point through 360 degrees.

BECMG

Becoming group

Bernoulli’s Principle

A principle that explains how the pressure of a moving fluid varies with its speed of motion. An increase in the speed of movement causes a decrease in the fluid’s pressure.

Blast Fence

A barrier that is used to divert or dissipate jet or propeller blast.

Blast Pad

A surface adjacent to the ends of a runway provided to reduce the erosive effect of jet blast and propeller wash.

Blind Spot

An area from which radio transmissions and/or radar echoes cannot be received. The term is also used to describe portions of the airport not visible from the control tower.

Blind Transmission

A transmission from one station to other stations in circumstances where two-way communication cannot be established, but where it is believed that the called stations may be able to receive the transmission.

Blind Zone

Blind Spot. An area from which radio transmissions and/or radar echoes cannot be received. The term is also used to describe portions of the airport not visible from the control tower.

Blocked

Phraseology used to indicate that a radio transmission has been distorted or interrupted due to multiple simultaneous radio transmissions.

Boundary Lights

Lights defining the perimeter of an airport or landing area.

Braking Action (Good, Fair, Poor, Or Nil)

A report of conditions on the airport movement area providing a pilot with a degree/quality of braking that he/she might expect. Braking action is reported in terms of good, fair, poor, or nil.

Braking Action Advisories

When tower controllers have received runway braking action reports which include the terms “fair,” “poor,” or “nil,” or whenever weather conditions are conducive to deteriorating or rapidly changing runway braking conditions, the tower will include on the ATIS broadcast the statement, “Braking action advisories are in effect” on the ATIS broadcast. During the time braking action advisories are in effect, ATC will issue the latest braking action report for the runway in use to each arriving and departing aircraft. Pilots should be prepared for deteriorating braking conditions and should request current runway condition information if not volunteered by controllers. Pilots should also be prepared to provide a descriptive runway condition report to controllers after landing.

Broadcast

Transmission of information for which an acknowledgement is not expected.

C/A

Coarse Acquisition

CAA

Civil Aeronautics Administration

Cage

The black markings on the ball instrument indicating its neutral position.

Calculated Landing Time

A term that may be used in place of tentative or actual calculated landing time, whichever applies.

Calendar Month

A time period used by the FAA for certification and currency purposes. A calendar month extends from a given day until midnight of the last day of that month.

Calibrated

The instrument indication compared with a standard value to determine the accuracy of the instrument.

Calibrated airspeed

The speed at which the aircraft is moving through the air, found by correcting IAS for instrument and position errors.

Calibrated orifice

A hole of specific diameter used to delay the pressure change in the case of a vertical speed indicator.

Cardinal Altitudes

“Odd” or “Even” thousand-foot altitudes or flight levels; e.g., 5,000, 6,000, 7,000, FL 250, FL 260, FL 270.

Cardinal Flight Levels

Cardinal Altitudes. “Odd” or “Even” thousand-foot altitudes or flight levels; e.g., 5,000, 6,000, 7,000, FL 250, FL 260, FL 270.

CARTS

Common Automated Radar Terminal System (ARTS) (to include ARTS IIIE and ARTS IIE)

CAS

Calibrated Airspeed.

CAT

Clear Air Turbulence

Category A

An Aircraft Approach Category. Speed less than 91 knots.

Category B

An Aircraft Approach Category. Speed 91 knots or more but less than 121 knots.

Category C

An Aircraft Approach Category. Speed 121 knots or more but less than 141 knots.

Category D

An Aircraft Approach Category. Speed 141 knots or more but less than 166 knots.

Category E

An Aircraft Approach Category. Speed 166 knots or more.

CDI

Course Deviation Indicator

CDM

Collaborative Decision Making. Cooperative effort between the various components of aviation transportation, both government and industry, to exchange information for better decision making.

Ceiling

The height above the earth’s surface of the lowest layer of clouds, which is reported as broken or overcast, or the vertical visibility into an obscuration.

Center

Air Route Traffic Control Center.

Center Weather Advisory

An unscheduled weather advisory issued by Center Weather Service Unit meteorologists for ATC use to alert pilots of existing or anticipated adverse weather conditions within the next 2 hours. A CWA may modify or redefine a SIGMET.

Center’s Area

The specified airspace within which an air route traffic control center (ARTCC) provides air traffic control and advisory service.

Centrifugal force

An outward force, that opposes centripetal force, resulting from the effect of inertia during a turn.

Centripetal force

A center-seeking force directed inward toward the center of rotation created by the horizontal component of lift in turning flight.

CFA

Controlled Firing Area

CFIT

Controlled Flight into Terrain

CFR

Code of Federal Regulations

Chaff

Thin, narrow metallic reflectors of various lengths and frequency responses, used to reflect radar energy. These reflectors when dropped from aircraft and allowed to drift downward result in large targets on the radar display.

Charted VFR Flyways

Charted VFR Flyways are flight paths recommended for use to bypass areas heavily traversed by large turbine-powered aircraft. Pilot compliance with recommended flyways and associated altitudes is strictly voluntary. VFR Flyway Planning charts are published on the back of existing VFR Terminal Area charts.

Chase Aircraft

An aircraft flown in proximity to another aircraft normally to observe its performance during training or testing.

CHDO

An FAA Flight Standards Certificate Holding District Office.

Checklist

A tool that is used as a human factors aid in aviation safety. It is a systematic and sequential list of all operations that must be performed to properly accomplish a task.

Circle To Runway (Runway Number)

Used by ATC to inform the pilot that he/she must circle to land because the runway in use is other than the runway aligned with the instrument approach procedure. When the direction of the circling maneuver in relation to the airport/runway is required, the controller will state the direction (eight cardinal compass points) and specify a left or right downwind or base leg as appropriate; e.g., “Cleared VOR Runway Three Six Approach circle to Runway Two Two,” or “Circle northwest of the airport for a right downwind to Runway Two Two.”

Circle-To-Land Maneuver

A maneuver initiated by the pilot to align the aircraft with a runway for landing when a straight-in landing from an instrument approach is not possible or is not desirable. At tower controlled airports, this maneuver is made only after ATC authorization has been obtained and the pilot has established required visual reference to the airport.

Circling Minima

Landing Minimums [for a circling approach].

Civil Air Regulation (CAR)

Predecessor to the Federal Aviation Regulations.

Civil aircraft

Aircraft other than public aircraft.

Class

(1) As used with respect to the certification, ratings, privileges, and limitations of airmen, a classification of aircraft within a category having similar operating characteristics. Examples include: single engine; multiengine; land; water; gyroplane; helicopter; airship; and free balloon; and
(2) As used with respect to the certification of aircraft, a broad grouping of aircraft having similar characteristics of propulsion, flight, or landing. Examples include: airplane; rotorcraft; glider; balloon; landplane; and seaplane.

Class A airspace

Airspace from 18,000 feet MSL up to and including FL 600, including the airspace overlying the waters within 12 NM of the coast of the 48 contiguous states and Alaska; and designated international airspace beyond 12 NM of the coast of the 48 contiguous states and Alaska within areas of domestic radio navigational signal or ATC radar coverage, and within which domestic procedures are applied.

Class B airspace

Airspace from the surface to 10,000 feet MSL surrounding the nation’s busiest airports in terms of IFR operations or passenger numbers. The configuration of each Class B airspace is individually tailored and consists of a surface area and two or more layers, and is designed to contain all published instrument procedures once an aircraft enters the airspace. For all aircraft, an ATC clearance is required to operate in the area, and aircraft so cleared receive separation services within the airspace.

Class C airspace

Airspace from the surface to 4,000 feet above the airport elevation (charted in MSL) surrounding those airports having an operational control tower, serviced by radar approach control, and having a certain number of IFR operations or passenger numbers. Although the configuration of each Class C airspace area is individually tailored, the airspace usually consists of a 5 NM radius core surface area that extends from the surface up to 4,000 feet above the airport elevation, and a 10 NM radius shelf area that extends from 1,200 feet to 4,000 feet above the airport elevation.

Class C Service

This service provides, in addition to basic radar service, approved separation between IFR and VFR aircraft, and sequencing of VFR aircraft, and sequencing of VFR arrivals to the primary airport.

Class D airspace

Airspace from the surface to 2,500 feet above the airport elevation (charted in MSL) surrounding those airports that have an operational control tower. The configuration of each Class D airspace area is individually tailored, and when instrument procedures are published, the airspace is normally designed to contain the procedures.

Class E

Generally, if the airspace is not Class A, Class B, Class C, or Class D, and it is controlled airspace, it is Class E airspace. Class E airspace extends upward from either the surface or a designated altitude to the overlying or adjacent controlled airspace. When designated as a surface area, the airspace will be configured to contain all instrument procedures. Also in this class are Federal airways, airspace beginning at either 700 or 1,200 feet AGL used to transition to/from the terminal or en route environment, en route domestic, and offshore airspace areas designated below 18,000 feet MSL. Unless designated at a lower altitude, Class E airspace begins at 14,500 MSL over the United States, including that airspace overlying the waters within 12 nautical miles of the coast of the 48 contiguous States and Alaska, up to, but not including 18,000 feet MSL, and the airspace above FL 600.

Class G airspace

Airspace that is uncontrolled, except when associated with a temporary control tower, and has not been designated as Class A, Class B, Class C, Class D, or Class E airspace.

Clean configuration

A configuration in which all flight control surfaces have been placed to create minimum drag. In most aircraft this means flaps and gear retracted.

Clear Air Turbulence (CAT)

Turbulence encountered in air where no clouds are present. This term is commonly applied to high-level turbulence associated with wind shear. CAT is often encountered in the vicinity of the jet stream.

Clear Ice

A glossy, clear, or translucent ice formed by the relatively slow freezing or large supercooled water droplets.

Clear Of The Runway

A. Taxiing aircraft, which is approaching a runway, is clear of the runway when all parts of the aircraft are held short of the applicable runway holding position marking.
B. A pilot or controller may consider an aircraft, which is exiting or crossing a runway, to be clear of the runway when all parts of the aircraft are beyond the runway edge and there are no restrictions to its continued movement beyond the applicable runway holding position marking.
C. Pilots and controllers shall exercise good judgement to ensure that adequate separation exists between all aircraft on runways and taxiways at airports with inadequate runway edge lines or holding position markings.

Clearance

ATC permission for an aircraft to proceed under specified traffic conditions within controlled airspace, for the purpose of providing separation between known aircraft.

Clearance Void If Not Off By (Time)

Used by ATC to advise an aircraft that the departure clearance is automatically canceled if takeoff is not made prior to a specified time. The pilot must obtain a new clearance or cancel his/her IFR flight plan if not off by the specified time.

Cleared (Type Of) Approach

ATC authorization for an aircraft to execute a specific instrument approach procedure to an airport; e.g., “Cleared ILS Runway Three Six Approach.”

Cleared Approach

ATC authorization for an aircraft to execute any standard or special instrument approach procedure for that airport. Normally, an aircraft will be cleared for a specific instrument approach procedure.

Cleared As Filed

Means the aircraft is cleared to proceed in accordance with the route of flight filed in the flight plan. This clearance does not include the altitude, DP, or DP Transition.

Cleared For Takeoff

ATC authorization for an aircraft to depart. It is predicated on known traffic and known physical airport conditions.

Cleared For The Option

ATC authorization for an aircraft to make a touch-and-go, low approach, missed approach, stop and go, or full stop landing at the discretion of the pilot. It is normally used in training so that an instructor can evaluate a student’s performance under changing situations.

Cleared Through

ATC authorization for an aircraft to make intermediate stops at specified airports without refiling a flight plan while en route to the clearance limit.

Cleared To Land

ATC authorization for an aircraft to land. It is predicated on known traffic and known physical airport conditions.

Climb To VFR

ATC authorization for an aircraft to climb to VFR conditions within Class B, C, D, and E surface areas when the only weather limitation is restricted visibility. The aircraft must remain clear of clouds while climbing to VFR.

Climbout

That portion of flight operation between takeoff and the initial cruising altitude.

Close Parallel Runways

Two parallel runways whose extended centerlines are separated by less than 4,300 feet, having a Precision Runway Monitoring (PRM) system that permits simultaneous independent ILS approaches.

Closed Runway

A runway that is unusable for aircraft operations. Only the airport management/military operations office can close a runway.

Closed Traffic

Successive operations involving takeoffs and landings or low approaches where the aircraft does not exit the traffic pattern.

Cloud

A cloud is a visible accumulation of minute water droplets and/or ice particles in the atmosphere above the Earth’s surface. Cloud differs from ground fog, fog, or ice fog only in that the latter are, by definition, in contact with the Earth’s surface.

CLSD

Closed

CLT

Calculated Landing Time

Clutter

In radar operations, clutter refers to the reception and visual display of radar returns caused by precipitation, chaff, terrain, numerous aircraft targets, or other phenomena. Such returns may limit or preclude ATC from providing services based on radar.

COA

Certificate of Waiver or Authorization

Coastal Air Defense Identification Zone

An ADIZ over the coastal waters of the United States.

Collision Hazard

A condition, event, or circumstance that could induce an occurrence of a collision or surface accident or incident.

Commercial operator

A person who, for compensation or hire, engages in the carriage by aircraft in air commerce of persons or property, other than as an air carrier or foreign air carrier or under the authority of Part 375 of this title. Where it is doubtful that an operation is for “compensation or hire”, the test applied is whether the carriage by air is merely incidental to the person’s other business or is, in itself, a major enterprise for profit.

Common ARTS

Includes ARTS IIE, ARTS IIIE; and ARTS IIIE with ACD (see DTAS) which combines functionalities of the previous ARTS systems.

Common Traffic Advisory Frequency (CTAF)

A frequency designed for the purpose of carrying out airport advisory practices while operating to or from an airport without an operating control tower. The CTAF may be a UNICOM, Multicom, FSS, or tower frequency and is identified in appropriate aeronautical publications.

Compass course

A true course corrected for variation and deviation errors.

Compass Locator

A low power, low or medium frequency (L/MF) radio beacon installed at the site of the outer or middle marker of an instrument landing system (ILS). It can be used for navigation at distances of approximately 15 miles or as authorized in the approach procedure.

Compass Rose

A circle, graduated in degrees, printed on some charts or marked on the ground at an airport. It is used as a reference to either true or magnetic direction.

Complex aircraft

An aircraft with retractable landing gear, flaps, and a controllable pitch propeller.

Computer navigation fix

A point used to define a navigation track for an airborne computer system such as GPS or FMS.

Cone of confusion

A cone-shaped volume of airspace directly above a VOR station where no signal is received, causing the CDI to fluctuate.

Confidence Maneuver

A confidence maneuver consists of one or more turns, a climb or descent, or other maneuver to determine if the pilot in command (PIC) is able to receive and comply with ATC instructions.

Conflict Alert

A function of certain air traffic control automated systems designed to alert radar controllers to existing or pending situations between tracked targets (known IFR or VFR aircraft) that require his/her immediate attention/action.

Conflict Resolution

The resolution of potential conflictions between aircraft that are radar identified and in communication with ATC by ensuring that radar targets do not touch. Pertinent traffic advisories shall be issued when this procedure is applied. Note: This procedure shall not be provided utilizing mosaic radar systems.

Consolan

A low frequency, long-distance NAVAID used principally for transoceanic navigations.

Constant-speed propeller

A controllable-pitch propeller whose pitch is automatically varied in flight by a governor to maintain a constant rpm in spite of varying air loads.

Contact

A. Establish communication with (followed by the name of the facility and, if appropriate, the frequency to be used).
B. A flight condition wherein the pilot ascertains the attitude of his/her aircraft and navigates by visual reference to the surface.

Contaminated Runway

A runway is considered contaminated whenever standing water, ice, snow, slush, frost in any form, heavy rubber, or other substances are present. A runway is contaminated with respect to rubber deposits or other friction-degrading substances when the average friction value for any 500-foot segment of the runway within the ALD fails below the recommended minimum friction level and the average friction value in the adjacent 500-foot segments falls below the maintenance planning friction level.

Conterminous U.S.

The 48 adjoining States and the District of Columbia.

Continental United States

The 49 States located on the continent of North America and the District of Columbia.

Continue

When used as a control instruction should be followed by another word or words clarifying what is expected of the pilot. Example: “continue taxi,” “continue descent,” “continue inbound,” etc.

Control Area [ICAO]

A controlled airspace extending upwards from a specified limit above the earth.

Control Sector

An airspace area of defined horizontal and vertical dimensions for which a controller or group of controllers has air traffic control responsibility, normally within an air route traffic control center or an approach control facility. Sectors are established based on predominant traffic flows, altitude strata, and controller workload. Pilot-communications during operations within a sector are normally maintained on discrete frequencies assigned to the sector.

Controlled airspace

An airspace of defined dimensions within which ATC service is provided to IFR and VFR flights in accordance with the airspace classification. It includes Class A, Class B, Class C, Class D, and Class E airspace.

Controlled Firing Area

A controlled firing area is established to contain activities, which if not conducted in a controlled environment, would be hazardous to nonparticipating aircraft.

Controller

Air Traffic Control Specialist.

Convective SIGMET

A weather advisory concerning convective weather significant to the safety of all aircraft. Convective SIGMETs are issued for tornadoes, lines of thunderstorms, embedded thunderstorms of any intensity level, areas of thunderstorms greater than or equal to VIP level 4 with an area coverage of 4/10 (40%) or more, and hail 3/4 inch or greater.

Coordinated flight

Flight with a minimum disturbance of the forces maintaining equilibrium, established via effective control use.

Coordinates

The intersection of lines of reference, usually expressed in degrees/minutes/seconds of latitude and longitude, used to determine position or location.

Copter

Helicopter.

Correction

An error has been made in the transmission and the correct version follows.

Course

The intended direction of flight in the horizontal plane measured in degrees from north.

CPDLC

Controller Pilot Data Link Communications

Crew resource management (CRM)

The application of team management concepts in the flight deck environment. It was initially known as cockpit resource management, but as CRM programs evolved to include cabin crews, maintenance personnel, and others, the phrase “crew resource management” was adopted. This includes single pilots, as in most general aviation aircraft. Pilots of small aircraft, as well as crews of larger aircraft, must make effective use of all available resources; human resources, hardware, and information. A current definition includes all groups routinely working with the flight crew who are involved in decisions required to operate a flight safely. These groups include, but are not limited to pilots, dispatchers, cabin crewmembers, maintenance personnel, and air traffic controllers. CRM is one way of addressing the challenge of optimizing the human/machine interface and accompanying interpersonal activities.

Critical angle of attack

The angle of attack at which a wing stalls regardless of airspeed, flight attitude, or weight.

Critical areas

Areas where disturbances to the ILS localizer and glideslope courses may occur when surface vehicles or aircraft operate near the localizer or glideslope antennas.

CRM

Crew Resource Management.

Cross Controlled

A condition where aileron deflection is in the opposite direction of rudder deflection.

Crosswind

A. When used concerning the traffic pattern, the word means “crosswind leg.” B. When used concerning wind conditions, the word means a wind not parallel to the runway or the path of an aircraft.

Crosswind Component

The wind component, measured in knots, at 90° to the longitudinal axis of the runway.

Crosswind Leg

A flight path at right angles to the landing runway off its upwind end.

Cruise

Used in an ATC clearance to authorize a pilot to conduct flight at any altitude from the minimum IFR altitude up to and including the altitude specified in the clearance. The pilot may level off at any intermediate altitude within this block of airspace. Climb/descent within the block is to be made at the discretion of the pilot. However, once the pilot starts descent and verbally reports leaving an altitude in the block, he/she may not return to that altitude without additional ATC clearance. Further, it is approval for the pilot to proceed to and make an approach at destination airport and can be used in conjunction with: a. An airport clearance limit at locations with a standard/special instrument approach procedure. The CFRs require that if an instrument letdown to an airport is necessary, the pilot shall make the letdown in accordance with a standard/special instrument approach procedure for that airport, or b. An airport clearance limit at locations that are within/below/outside controlled airspace and without a standard/special instrument approach procedure. Such a clearance is NOT AUTHORIZATION for the pilot to descend under IFR conditions below the applicable minimum IFR altitude nor does it imply that ATC is exercising control over aircraft in Class G airspace; however, it provides a means for the aircraft to proceed to destination airport, descend, and land in accordance with applicable CFRs governing VFR flight operations. Also, this provides search and rescue protection until such time as the IFR flight plan is closed.

Cruise Climb

A climb technique employed by aircraft, usually at a constant power setting, resulting in an increase of altitude as the aircraft weight decreases.

Cruising Altitude

An altitude or flight level maintained during en route level flight. This is a constant altitude and should not be confused with a cruise clearance.

Cruising Level

Cruising Altitude. An altitude or flight level maintained during en route level flight. This is a constant altitude and should not be confused with a cruise clearance.

CTAF

Common Traffic Advisory Frequency

CVFP

Charted Visual Flight Procedure

CVRS

Computerized Voice Reservation System

D-ATIS

Digital-Automatic Terminal Information Service

D.C.

Direct Current.

DCA

Ronald Reagan Washington National Airport

DCP

Data Collection Package

Dead reckoning

Navigation of an airplane solely by means of computations based on airspeed, course, heading, wind direction and speed, groundspeed, and elapsed time.

Deceleration error

A magnetic compass error that occurs when the aircraft decelerates while flying on an easterly or westerly heading, causing the compass card to rotate toward South.

Decision Altitude/Decision Height [ICAO]

A specified altitude or height (A/H) in the precision approach at which a missed approach must be initiated if the required visual reference to continue the approach has not been established. Note 1: Decision altitude [DA] is referenced to mean sea level [MSL] and decision height [DH] is referenced to the threshold elevation. Note 2: The required visual reference means that section of the visual aids or of the approach area which should have been in view for sufficient time for the pilot to have made an assessment of the aircraft position and rate of change of position, in relation to the desired flight path.

Defense Visual Flight Rules

Rules applicable to flights within an ADIZ conducted under the visual flight rules in 14 CFR Part 91.

Delta

A Greek letter expressed by the symbol ∆ to indicate a change of values. As an example, ∆CG indicates a change (or movement) of the CG.

Density Altitude

This altitude is pressure altitude corrected for variations from standard temperature. When conditions are standard, pressure altitude and density altitude are the same. If the temperature is above standard, the density altitude is higher than pressure altitude. If the temperature is below standard, the density altitude is lower than pressure altitude. This is an important altitude because it is directly related to the airplane’s performance.

Departure Center

The ARTCC having jurisdiction for the airspace that generates a flight to the impacted airport.

Departure Control

A function of an approach control facility providing air traffic control service for departing IFR and, under certain conditions, VFR aircraft.

Departure Time

The time an aircraft becomes airborne.

DER

Departure End of Runway

Designated Pilot Examiner (DPE)

An individual designated by the FAA to administer practical tests to pilot applicants.

Desired Course

Either True Course or Magnetic Course.

Desired Track

The planned or intended track between two waypoints. It is measured in degrees from either magnetic or true north. The instantaneous angle may change from point to point along the great circle track between waypoints.

Deviation

A magnetic compass error caused by local magnetic fields within the aircraft. Deviation error is different on each heading.

DF

Direction Finder

DF Fix

The geographical location of an aircraft obtained by one or more direction finders.

DF Guidance

Headings provided to aircraft by facilities equipped with direction finding equipment. These headings, if followed, will lead the aircraft to a predetermined point such as the DF station or an airport. DF guidance is given to aircraft in distress or to other aircraft which request the service. Practice DF guidance is provided when workload permits.

DF Steer

DF (Direction Finding) Guidance. Headings provided to aircraft by facilities equipped with direction finding equipment. These headings, if followed, will lead the aircraft to a predetermined point such as the DF station or an airport. DF guidance is given to aircraft in distress or to other aircraft which request the service. Practice DF guidance is provided when workload permits.

DGPS

Differential Global Positioning System.

Differential Global Positioning System (DGPS)

A system that improves the accuracy of Global Navigation Satellite Systems (GNSS) by measuring changes in variables to provide satellite positioning corrections.

Differential pressure

A difference between two pressures. The measurement of airspeed is an example of the use of differential pressure.

Direct

Straight line flight between two navigational aids, fixes, points, or any combination thereof. When used by pilots in describing off-airway routes, points defining direct route segments become compulsory reporting points unless the aircraft is under radar contact.

Direct indication

The true and instantaneous reflection of aircraft pitch-and-bank attitude by the miniature aircraft, relative to the horizon bar of the attitude indicator.

Direct User Access Terminal System (DUATS)

A system that provides current FAA weather and flight plan filing services to certified civil pilots, via personal computer, modem, or telephone access to the system. Pilots can request specific types of weather briefings and other pertinent data for planned flights.

Direction Finder

A radio receiver equipped with a directional sensing antenna used to take bearings on a radio transmitter. Specialized radio direction finders are used in aircraft as air navigation aids. Others are ground-based, primarily to obtain a “fix” on a pilot requesting orientation assistance or to locate downed aircraft. A location “fix” is established by the intersection of two or more bearing lines plotted on a navigational chart using either two separately located Direction Finders to obtain a fix on an aircraft or by a pilot plotting the bearing indications of his/her DF on two separately located ground-based transmitters, both of which can be identified on his/her chart. UDFs receive signals in the ultra high frequency radio broadcast band; VDFs in the very high frequency band; and UVDFs in both bands. ATC provides DF service at those air traffic control towers and flight service stations listed in the Airport/Facility Directory and the DOD FLIP IFR En Route Supplement.

Directly Behind

An aircraft is considered to be operating directly behind when it is following the actual flight path of the lead aircraft over the surface of the earth except when applying wake turbulence separation criteria.

Discrete Beacon Code

Discrete Code. [As used in the Air Traffic Control Radar Beacon System (ATCRBS), any one of the 4096 selectable Mode 3/A aircraft transponder codes except those ending in zero zero; e.g., discrete codes: 0010, 1201, 2317, 7777; nondiscrete codes: 0100, 1200, 7700. Nondiscrete codes are normally reserved for radar facilities that are not equipped with discrete decoding capability and for other purposes such as emergencies (7700), VFR aircraft (1200), etc.]

Discrete Code

As used in the Air Traffic Control Radar Beacon System (ATCRBS), any one of the 4096 selectable Mode 3/A aircraft transponder codes except those ending in zero zero; e.g., discrete codes: 0010, 1201, 2317, 7777; nondiscrete codes: 0100, 1200, 7700. Nondiscrete codes are normally reserved for radar facilities that are not equipped with discrete decoding capability and for other purposes such as emergencies (7700), VFR aircraft (1200), etc.

Discrete Frequency

A separate radio frequency for use in direct pilot-controller communications in air traffic control which reduces frequency congestion by controlling the number of aircraft operating on a particular frequency at one time. Discrete frequencies are normally designated for each control sector in en route/terminal ATC facilities. Discrete frequencies are listed in the Airport/Facility Directory and the DOD FLIP IFR En Route Supplement.

Displaced Threshold

A threshold that is located at a point on the runway other than the designated beginning of the runway.

Distance measuring equipment (DME)

A pulse-type electronic navigation system that shows the pilot, by an instrument-panel indication, the number of nautical miles between the aircraft and a ground station or waypoint.

Distant Early Warning Identification Zone (DEWIZ)

An ADIZ over the coastal waters of the State of Alaska.

Distress

A condition of being threatened by serious and/or imminent danger and of requiring immediate assistance.

Ditching

Emergency landing in water.

Dive Brakes

Speed Brakes.

Diversion (DVRSN)

Flights that are required to land at other than their original destination for reasons beyond the control of the pilot/company, e.g. periods of significant weather.

DME

Distance Measuring Equipment

DME Fix

A geographical position determined by reference to a navigational aid which provides distance and azimuth information. It is defined by a specific distance in nautical miles and a radial, azimuth, or course (i.e., localizer) in degrees magnetic from that aid.

Doghouse

A turn-and-slip indicator dial mark in the shape of a doghouse.

Domestic Air Defense Identification Zone

An ADIZ within the United States along an international boundary of the United States.

Domestic Airspace

Airspace which overlies the continental land mass of the United States plus Hawaii and U.S. possessions. Domestic airspace extends to 12 miles offshore.

DOT

Department of Transportation

Double gimbal

A type of mount used for the gyro in an attitude instrument. The axes of the two gimbals are at right angles to the spin axis of the gyro, allowing free motion in two planes around the gyro.

Downburst

A strong downdraft which induces an outburst of damaging winds on or near the ground. Damaging winds, either straight or curved, are highly divergent. The sizes of downbursts vary from 1/2 mile or less to more than 10 miles. An intense downburst often causes widespread damage. Damaging winds, lasting 5 to 30 minutes, could reach speeds as high as 120 knots.

Downwind Leg

A flight path parallel to the landing runway in the direction opposite to landing. The downwind leg normally extends between the crosswind leg and the base leg.

Drag Chute

A parachute device installed on certain aircraft which is deployed on landing roll to assist in deceleration of the aircraft.

Drag curve

The curve created when plotting induced drag and parasite drag.

Drift angle

Angle between heading and track.

DUATS

Direct User Access Terminal System (shut down May 16, 2018).

Duplex

Transmitting on one frequency and receiving on a separate frequency.

Duty Runway

Runway In Use/Active Runway/Duty Runway.

DVFR Flight Plan

A flight plan filed for a VFR aircraft which intends to operate in airspace within which the ready identification, location, and control of aircraft are required in the interest of national security.

Dynamic

Continuous review, evaluation, and change to meet demands.

Dynamic hydroplaning

A condition that exists when landing on a surface with standing water deeper than the tread depth of the tires. When the brakes are applied, there is a possibility that the brake will lock up and the tire will ride on the surface of the water, much like a water ski. When the tires are hydroplaning, directional control and braking action are virtually impossible. An effective anti-skid system can minimize the effects of hydroplaning.

E-MSAW

En Route Minimum Safe Altitude Warning

EAS

Equivalent Airspeed.

EDCT

Expect Departure Clearance Time. The time issued to a flight to indicate when it can expect to receive departure clearance. EDCTs are issued as part of Traffic Management Programs, such as a Ground Delay Program (GDP).

Eddy current damping

The decreased amplitude of oscillations by the interaction of magnetic fields. In the case of a vertical card magnetic compass, flux from the oscillating permanent magnet produces eddy currents in a damping disk or cup. The magnetic flux produced by the eddy currents opposes the flux from the permanent magnet and decreases the oscillations.

Eddy currents

Current induced in a metal cup or disc when it is crossed by lines of flux from a moving magnet.

EFAS

En Route Flight Advisory Service

EFD

Electronic Flight Display.

Electronic flight display (EFD)

For the purpose of standardization, any flight instrument display that uses LCD or other image-producing system (cathode ray tube (CRT), etc.).

Elevator

The horizontal, movable primary control surface in the tail section, or empennage, of an airplane. The elevator is hinged to the trailing edge of the fixed horizontal stabilizer.

ELT

Emergency Locator Transmitter

EM wave

Electromagnetic wave.

EMAS

Engineered Materials Arresting System

EMERG

Emergency

A distress or urgent condition.

Emergency Locator Transmitter

A radio transmitter attached to the aircraft structure which operates from its own power source on 121.5 MHz and 243.0 MHz. It aids in locating downed aircraft by radiating a downward sweeping audio tone, 2-4 times per second. It is designed to function without human action after an accident. [The 121.5 band is no longer monitored by satellite. The newest version uses 406.0MHz]

Empennage

The section of the airplane that consists of the vertical stabilizer, the horizontal stabilizer, and the associated control surfaces.

EMS

Emergency Medical Service

En Route Flight Advisory Service

A service specifically designed to provide, upon pilot request, timely weather information pertinent to his/her type of flight, intended route of flight, and altitude. The FSSs providing this service are listed in the Airport/Facility Directory.

En route high-altitude charts

Aeronautical charts for en route instrument navigation at or above 18,000 feet MSL.

En Route Low Altitude Charts

Provide aeronautical information for en route instrument navigation (IFR) in the low altitude stratum. Information includes the portrayal of airways, limits of controlled airspace, position identification and frequencies of radio aids, selected airports, minimum en route and minimum obstruction clearance altitudes, airway distances, reporting points, restricted areas, and related data. Area charts, which are a part of this series, furnish terminal data at a larger scale in congested areas.

En route low-altitude charts

Aeronautical charts for en route IFR navigation below 18,000 feet MSL.

Encoding altimeter

A special type of pressure altimeter used to send a signal to the air traffic controller on the ground, showing the pressure altitude the aircraft is flying.

Enhanced flight visibility (EFV)

The average forward horizontal distance, from the cockpit of an aircraft in flight, at which prominent topographical objects may be clearly distinguished and identified by day or night by a pilot using an enhanced flight vision system.

Enhanced flight vision system (EFVS)

An electronic means to provide a display of the forward external scene topography (the natural or manmade features of a place or region especially in a way to show their relative positions and elevation) through the use of imaging sensors, such as a forward looking infrared, millimeter wave radiometry, millimeter wave radar, low light level image intensifying.

EPE

Estimate of Position Error

Equi-Time Point

A point on the route of flight where the flight time, considering wind, to each of two selected airports is equal.

EQUIP

Equipment

Equivalent airspeed

Airspeed equivalent to CAS in standard atmosphere at sea level. As the airspeed and pressure altitude increase, the CAS becomes higher than it should be, and a correction for compression must be subtracted from the CAS.

Established

To be stable or fixed on a route, route segment, altitude, heading, etc.

Estimated Time En Route

The estimated flying time from departure point to destination (lift-off to touchdown).

Estimated Time Of Arrival

The time the flight is estimated to arrive at the gate (scheduled operators) or the actual runway on times for nonscheduled operators.

ESV

Expanded Service Volume

ETA

Estimated Time of Arrival

ETD

Estimated Time of Departure

ETE

Estimated Time En Route

Extended over-water operation

(1) With respect to aircraft other than helicopters, an operation over water at a horizontal distance of more than 50 nautical miles from the nearest shoreline; and
(2) With respect to helicopters, an operation over water at a horizontal distance of more than 50 nautical miles from the nearest shoreline and more than 50 nautical miles from an off-shore heliport structure.

FA

Area Forecast (Discontinued, replaced by Graphical Forecasts for Aviation)

FAA

Federal Aviation Administration.

FAASTeam

Federal Aviation Administration Safety Team.

FAASTeam Program Manager

The person who designs, implements, and evaluates the FAASTeam within the FAA flight standards district office (FSDO) area of responsibility.

FAASTeam Representative

A volunteer within the aviation community who shares technical expertise and professional knowledge as a part of the FAASTeam.

FAROS

Final Approach Runway Occupancy Signal

Fast File

A system whereby a pilot files a flight plan via telephone that is tape recorded and then transcribed for transmission to the appropriate air traffic facility. Locations having a fast file capability are contained in the Airport/Facility Directory. (Alaska only.)

FAWP

Final Approach Waypoint

FB

Fly-by

FCC

Federal Communications Commission

FD

Flight Director

FDC

Flight Data Center

FDC NOTAM

Flight Data Center Notice To Airmen

FDE

Fault Detection and Exclusion

Federal airways

Class E airspace areas that extend upward from 1,200 feet to, but not including, 18,000 feet MSL, unless otherwise specified.

Federal Aviation Administration Safety Team (FAASTeam)

An organization promoting safety standards and the reduction of aircraft related accidents. Each of the eight FAA Flight Standards regions have a dedicated FAASTeam office.

Ferry Flight

A flight for the purpose of: a. Returning an aircraft to base. b. Delivering an aircraft from one location to another. c. Moving an aircraft to and from a maintenance base. Ferry flights, under certain conditions, may be conducted under terms of a special flight permit.

FFS

Full Flight Simulator.

Field Elevation

Airport Elevation. The highest point of an airport’s usable runways measured in feet from mean sea level.

Filed

Normally used in conjunction with flight plans, meaning a flight plan has been submitted to ATC.

Filed Flight Plan

The flight plan as filed with an ATS unit by the pilot or his/her designated representative without any subsequent changes or clearances.

Final Approach

A flight path in the direction of landing along the extended runway centerline. The final approach normally extends from the base leg to the runway. An aircraft making a straight-in approach VFR is also considered to be on final approach.

Final Approach Runway Occupancy Signal (FAROS)

The Final Approach Runway Occupancy Signal (FAROS) is an automated safety system designed to notify pilots on approach to land that the runway is occupied or otherwise unsafe for landing. This pilot notification system is an FAA sponsored research and development effort that addresses the high priority safety hazards of runway incursions.

FIR

Flight Information Region

FIS

Flight Information Service

Fix

A geographical position determined by visual reference to the surface, by reference to one or more radio NAVAIDs, by celestial plotting, or by another navigational device.

Fixating

Staring at a single instrument, thereby interrupting the cross-check process.

Flammable

With respect to a fluid or gas, susceptible to igniting readily or to exploding.

Flaps

Hinged portion of the trailing edge between the ailerons and fuselage. In some aircraft ailerons and flaps are interconnected to produce full-span “flaperons.” In either case, flaps change the lift and drag on the wing.

Flight Check

A call-sign prefix used by FAA aircraft engaged in flight inspection/certification of navigational aids and flight procedures. The word “recorded” may be added as a suffix; e.g., “Flight Check 320 recorded” to indicate that an automated flight inspection is in progress in terminal areas.

Flight configurations

Adjusting the aircraft control surfaces (including flaps and landing gear) in a manner that will achieve a specified attitude.

Flight Following

Traffic Advisories.

Flight Information Service

A service provided for the purpose of giving advice and information useful for the safe and efficient conduct of flights.

Flight Level

A level of constant atmospheric pressure related to a reference datum of 29.92 inches of mercury. Each is stated in three digits that represent hundreds of feet. For example, flight level (FL) 250 represents a barometric altimeter indication of 25,000 feet; FL 255, an indication of 25,500 feet.

Flight path

The line, course, or track along which an aircraft is flying or is intended to be flown.

Flight patterns

Basic maneuvers, flown by reference to the instruments rather than outside visual cues, for the purpose of practicing basic attitude flying. The patterns simulate maneuvers encountered on instrument flights such as holding patterns, procedure turns, and approaches.

Flight Plan

Specified information relating to the intended flight of an aircraft that is filed orally or in writing with an FSS or an ATC facility.

Flight Recorder

A general term applied to any instrument or device that records information about the performance of an aircraft in flight or about conditions encountered in flight. Flight recorders may make records of airspeed, outside air temperature, vertical acceleration, engine RPM, manifold pressure, and other pertinent variables for a given flight.

Flight review

A 14 CFR 61.56 requirement designed to assess and update a pilot’s knowledge and skills.

Flight Service Station (FSS)

An air traffic facility which provides pilot briefings, flight plan processing, en route radio communications, search and rescue services, and assistance to lost aircraft and aircraft in emergency situations. FSSs also relay ATC clearances, process Notices to Airmen, broadcast aviation weather and aeronautical information, and notify Customs and Border Protection of transborder flights. In addition, at selected locations, FSSs provide En Route Flight Advisory Service (Flight Watch) and Airport Advisory Service (AAS). In Alaska, designated FSSs also provide TWEB recordings and take weather observations.

Flight simulation training device (FSTD)

A flight simulator or a flight training device.

Flight Standards District Office

An FAA field office serving an assigned geographical area and staffed with Flight Standards personnel who serve the aviation industry and the general public on matters relating to the certification and operation of air carrier and general aviation aircraft. Activities include general surveillance of operational safety, certification of airmen and aircraft, accident prevention, investigation, enforcement, etc.

Flight Test

A flight for the purpose of: a. Investigating the operation/flight characteristics of an aircraft or aircraft component. b. Evaluating an applicant for a pilot certificate or rating.

Flight time

(1) Pilot time that commences when an aircraft moves under its own power for the purpose of flight and ends when the aircraft comes to rest after landing; or
(2) For a glider without self-launch capability, pilot time that commences when the glider is towed for the purpose of flight and ends when the glider comes to rest after landing.

Flight training device (FTD)

A replica of aircraft instruments, equipment, panels, and controls in an open flight deck area or an enclosed aircraft cockpit replica. It includes the equipment and computer programs necessary to represent aircraft (or set of aircraft) operations in ground and flight conditions having the full range of capabilities of the systems installed in the device as described in part 60 of this chapter and the qualification performance standard (QPS) for a specific FTD qualification level.

Flight Visibility

The average forward horizontal distance, from the cockpit of an aircraft in flight, at which prominent unlighted objects may be seen and identified by day and prominent lighted objects may be seen and identified by night.

Flight Visibility [ICAO]

The visibility forward from the cockpit of an aircraft in flight.

Flight Watch

A shortened term for use in air-ground contacts to identify the flight service station providing En Route Flight Advisory Service; e.g., “Oakland Flight Watch.”

Floating

A condition when landing where the airplane does not settle to the runway due to excessive airspeed.

Fly Heading (Degrees)

Informs the pilot of the heading he/she should fly. The pilot may have to turn to, or continue on, a specific compass direction in order to comply with the instructions. The pilot is expected to turn in the shorter direction to the heading unless otherwise instructed by ATC.

FM

Fan Marker.

FMSP

Flight Management System Procedure

FOD

Foreign Object Damage.

Fog

Cloud consisting of numerous minute water droplets and based at the surface; droplets are small enough to be suspended in the earth’s atmosphere indefinitely. (Unlike drizzle, it does not fall to the surface. Fog differs from a cloud only in that a cloud is not based at the surface, and is distinguished from haze by its wetness and gray color.).

Force (F)

The energy applied to an object that attempts to cause the object to change its direction, speed, or motion. In aerodynamics, it is expressed as F, T (thrust), L (lift), W (weight), or D (drag), usually in pounds.

Form drag

The drag created because of the shape of a component or the aircraft.

Formation Flight

More than one aircraft which, by prior arrangement between the pilots, operate as a single aircraft with regard to navigation and position reporting. Separation between aircraft within the formation is the responsibility of the flight leader and the pilots of the other aircraft in the flight. This includes transition periods when aircraft within the formation are maneuvering to attain separation from each other to effect individual control and during join-up and breakaway. a. A standard formation is one in which a proximity of no more than 1 mile laterally or longitudinally and within 100 feet vertically from the flight leader is maintained by each wingman. b. Nonstandard formations are those operating under any of the following conditions: 1. When the flight leader has requested and ATC has approved other than standard formation dimensions. 2. When operating within an authorized altitude reservation (ALTRV) or under the provisions of a letter of agreement. 3. When the operations are conducted in airspace specifically designed for a special activity.

Forward Slip

A slip in which the airplane’s direction of motion continues the same as before the slip was begun. In a forward slip, the airplane’s longitudinal axis is at an angle to its flightpath.

FPA

Flight Path Angle

FPV

Flight Path Vector

FSDO

Flight Standards District Office

FSM

Flight Schedule Monitor. A tool used by Air Traffic Management Specialists to monitor air traffic demand at airports.

FSS

Flight Service Station. Air traffic facilities which provide pilot briefing, en route communications and VFR search and rescue services, assist lost aircraft and aircraft in emergency situations, relay ATC clearances, originate Notices to Airmen, broadcast aviation weather and NAS information, receive and process IFR flight plans, and monitor NAVAIDs. In addition, at selected locations, FSSs provide En Route Flight Advisory Service (Flight Watch), take weather observations, issue airport advisories, and advise Customs and Immigration of transborder flights.

FSTD

Flight Simulation Training Device.

FTD

Flight Training Device.

Fuel load

The expendable part of the load of the airplane. It includes only usable fuel, not fuel required to fill the lines or that which remains trapped in the tank sumps.

Fuel Remaining

A phrase used by either pilots or controllers when relating to the fuel remaining on board until actual fuel exhaustion. When transmitting such information in response to either a controller question or pilot initiated cautionary advisory to air traffic control, pilots will state the APPROXIMATE NUMBER OF MINUTES the flight can continue with the fuel remaining. All reserve fuel SHOULD BE INCLUDED in the time stated, as should an allowance for established fuel gauge system error.

Fuel Siphoning

Unintentional release of fuel caused by overflow, puncture, loose cap, etc.

Fuel Venting

Fuel Siphoning.

Fuselage

The section of the airplane that consists of the cabin and/or cockpit, containing seats for the occupants and the controls for the airplane.

GA

General Aviation

GAMA

General Aviation Manufacturers Association.

GBAS

Ground Based Augmentation System

GDP

Ground Delay Program. Ground Delay Programs are implemented to control air traffic volume to airports where the projected traffic demand is expected to exceed the airport´s acceptance rate for a lengthy period of time. Lengthy periods of demand exceeding acceptance rate are normally a result of the airport´s acceptance rate being reduced for some reason. The most common reason for a reduction in acceptance rate is adverse weather such as low ceilings and visibility.
How it works: Flights that are destined to the affected airport are issued Expect Departure Clearance Times (EDCT) at their point of departure. Flights that have been issued EDCTs are not permitted to depart until their Expect Departure Clearance Time. These ECDTs are calculated in such a way as to meter the rate that traffic arrives at the affected airport; ensuring that demand is equal to acceptance rate. The length of delays that result from the implementation of a Ground Delay Program is a factor of two things; how much greater than the acceptance rate the original demand was, and for what length of time the original demand was expected to exceed the acceptance rate.

General Aviation

That portion of civil aviation which encompasses all facets of aviation except air carriers holding a certificate of public convenience and necessity from the Civil Aeronautics Board and large aircraft commercial operators.

GEO

Geostationary Satellite

Gimbal ring

A type of support that allows an object, such as a gyroscope, to remain in an upright condition when its base is tilted.

Glidepath Intercept Altitude

Glideslope Intercept Altitude.

Glider

A heavier-than-air aircraft, that is supported in flight by the dynamic reaction of the air against its lifting surfaces and whose free flight does not depend principally on an engine.

Glideslope Intercept Altitude

The minimum altitude to intercept the glideslope/path on a precision approach. The intersection of the published intercept altitude with the glideslope/path, designated on Government charts by the lightning bolt symbol, is the precision FAF; however, when the approach chart shows an alternative lower glideslope intercept altitude, and ATC directs a lower altitude, the resultant lower intercept position is then the FAF.

Global navigation satellite system (GNSS)

Satellite navigation system that provides autonomous geospatial positioning with global coverage. It allows small electronic receivers to determine their location (longitude, latitude, and altitude) to within a few meters using time signals transmitted along a line of sight by radio from satellites.

Global Positioning System (GPS)

A space-base radio positioning, navigation, and time-transfer system. The system provides highly accurate position and velocity information, and precise time, on a continuous global basis, to an unlimited number of properly equipped users. The system is unaffected by weather, and provides a worldwide common grid reference system. The GPS concept is predicated upon accurate and continuous knowledge of the spatial position of each satellite in the system with respect to time and distance from a transmitting satellite to the user. The GPS receiver automatically selects appropriate signals from the satellites in view and translates these into three-dimensional position, velocity, and time. System accuracy for civil users is normally 100 meters horizontally.

GLS

GNSS Landing System

GNSS

Global Navigation Satellite System.

GNSSP

Global Navigation Satellite System Panel

Go Ahead

Proceed with your message. Not to be used for any other purpose.

Go Around

Instructions for a pilot to abandon his/her approach to landing. Additional instructions may follow. Unless otherwise advised by ATC, a VFR aircraft or an aircraft conducting visual approach should overfly the runway while climbing to traffic pattern altitude and enter the traffic pattern via the crosswind leg. A pilot on an IFR flight plan making an instrument approach should execute the published missed approach procedure or proceed as instructed by ATC; e.g., “Go around” (additional instructions if required).

GPS

Global Positioning System

GPWS

Ground Proximity Warning System.

Graveyard spiral

The illusion of the cessation of a turn while still in a prolonged, coordinated, constant rate turn, which can lead a disoriented pilot to a loss of control of the aircraft.

Great circle route

The shortest distance across the surface of a sphere (the Earth) between two points on the surface.

GRI

Group Repetition Interval

Ground Clutter

A pattern produced on the radar scope by ground returns which may degrade other radar returns in the affected area. The effect of ground clutter is minimized by the use of moving target indicator (MTI) circuits in the radar equipment resulting in a radar presentation which displays only targets which are in motion.

Ground Communication Outlet (GCO)

An unstaffed, remotely controlled, ground/ground communications facility. Pilots at uncontrolled airports may contact ATC and FSS via VHF to a telephone connection to obtain an instrument clearance or close a VFR or IFR flight plan. They may also get an updated weather briefing prior to takeoff. Pilots will use four “key clicks” on the VHF radio to contact the appropriate ATC facility or six “key clicks” to contact the FSS. The GCO system is intended to be used only on the ground.

Ground Effect

A condition of improved performance encountered when an airplane is operating very close to the ground. When an airplane’s wing is under the influence of ground effect, there is a reduction in upwash, downwash, and wingtip vortices. As a result of the reduced wingtip vortices, induced drag is reduced.

Ground Loop

A sharp, uncontrolled change of direction of an airplane on the ground.

Ground proximity warning system (GPWS)

A system designed to determine an aircraft’s clearance above the Earth and provides limited predictability about aircraft position relative to rising terrain.

Ground Speed

The speed of an aircraft relative to the surface of the earth.

Ground Track

The aircraft’s path over the ground when in flight.

Ground Visibility

Prevailing horizontal visibility near the earth’s surface as reported by the United States National Weather Service or an accredited observer.

Ground Visibility [ICAO]

The visibility at an aerodrome as reported by an accredited observer.

Groundspeed

Speed over the ground, either closing speed to the station or waypoint, or speed over the ground in whatever direction the aircraft is going at the moment, depending upon the navigation system used.

GS

Ground Stop. Ground Stops are implemented for a number of reasons. The most common reasons are:
To control air traffic volume to airports when the projected traffic demand is expected to exceed the airport´s acceptance rate for a short period of time.
To temporarily stop traffic allowing for the implementation of a longer-term solution, such as a Ground Delay Program.
The affected airport´s acceptance rate has been reduced to zero.
How it works: Flights that are destined to the affected airport are held at their departure point for the duration of the Ground Stop.

GWPS

Ground Proximity Warning System.

Gyrodyne

A rotorcraft whose rotors are normally engine-driven for takeoff, hovering, and landing, and for forward flight through part of its speed range, and whose means of propulsion, consisting usually of conventional propellers, is independent of the rotor system.

Gyroplane

A rotorcraft whose rotors are not engine-driven, except for initial starting, but are made to rotate by action of the air when the rotorcraft is moving; and whose means of propulsion, consisting usually of conventional propellers, is independent of the rotor system.

Gyroscopic precession

An inherent quality of rotating bodies, which causes an applied force to be manifested 90° in the direction of rotation from the point where the force is applied.

Handoff

An action taken to transfer the radar identification of an aircraft from one controller to another if the aircraft will enter the receiving controller’s airspace and radio communications with the aircraft will be transferred.

Have Numbers

Used by pilots to inform ATC that they have received runway, wind, and altimeter information only.

Hazardous Inflight Weather Advisory Service

Continuous recorded hazardous inflight weather forecasts broadcasted to airborne pilots over selected VOR outlets defined as an HIWAS Broadcast Area. Discontinued on January 8, 2020.

Hazardous Weather Information

Summary of significant meteorological information (SIGMET/WS), convective significant meteorological information (convective SIGMET/WST), urgent pilot weather reports (urgent PIREP/UUA), center weather advisories (CWA), airmen’s meteorological information (AIRMET/WA) and any other weather such as isolated thunderstorms that are rapidly developing and increasing in intensity, or low ceilings and visibilities that are becoming widespread which is considered significant and are not included in a current hazardous weather advisory.

HDTA

High Density Traffic Airports

Heading

The direction in which the nose of the aircraft is pointing during flight.

Heading Bug

A marker on the heading indicator that can be rotated to a specific heading for reference purposes, or to command an autopilot to fly that heading.

Heading Indicator

An instrument which senses airplane movement and displays heading based on a 360º azimuth, with the final zero omitted. The heading indicator, also called a directional gyro, is fundamentally a mechanical instrument designed to facilitate the use of the magnetic compass. The heading indicator is not affected by the forces that make the magnetic compass difficult to interpret.

Headwind Component

The component of atmospheric winds that acts opposite to the aircraft’s flightpath.

Heavy

An Aircraft Class Wake Turbulence Separation Minima. 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.

Helicopter

A rotorcraft that, for its horizontal motion, depends principally on its engine-driven rotors.

Helipad

A small, designated area, usually with a prepared surface, on a heliport, airport, landing/takeoff area, apron/ramp, or movement area used for takeoff, landing, or parking of helicopters.

Heliport

An area of land, water, or structure used or intended to be used for the landing and takeoff of helicopters and includes its buildings and facilities if any.

HEMS

Helicopter Emergency Medical Services

Hertz

The standard radio equivalent of frequency in cycles per second of an electromagnetic wave. Kilohertz (kHz) is a frequency of one thousand cycles per second. Megahertz (MHz) is a frequency of one million cycles per second.

HF

High Frequency.

HF Communications

High Frequency Communications.

Hg

Abbreviation for mercury, from the Latin hydrargyrum.

High Frequency

The frequency band between 3 and 30 MHz.

High Frequency Communications

High radio frequencies (HF) between 3 and 30 MHz used for air-to-ground voice communication in overseas operations.

High performance aircraft

An aircraft with an engine of more than 200 horsepower.

High Speed Exit

High Speed Taxiway.

High Speed Taxiway

A long radius taxiway designed and provided with lighting or marking to define the path of aircraft, traveling at high speed (up to 60 knots), from the runway center to a point on the center of a taxiway. Also referred to as long radius exit or turn-off taxiway. The high speed taxiway is designed to expedite aircraft turning off the runway after landing, thus reducing runway occupancy time.

High Speed Turnoff

High Speed Taxiway.

HIRL

High-Intensity Runway Light System.

HIWAS

Hazardous Inflight Weather Advisory Service. Discontinued on January 8, 2020.

HIWAS Broadcast Area

A geographical area of responsibility including one or more HIWAS outlet areas assigned to an AFSS/FSS for hazardous weather advisory broadcasting. Discontinued on January 8, 2020.

HIWAS Outlet Area

An area defined as a 150 NM radius of a HIWAS outlet, expanded as necessary to provide coverage. Discontinued on January 8, 2020.

Hold-Short Point

A point on the runway beyond which a landing aircraft with a LAHSO clearance is not authorized to proceed. This point may be located prior to an intersecting runway, taxiway, predetermined point, or approach/departure flight path.

Hold-Short Position Lights

Flashing in-pavement white lights located at specified hold-short points.

Hold-Short Position Marking

The painted runway marking located at the hold-short point on all LAHSO runways.

Hold-Short Position Signs

Red and white holding position signs located alongside the hold-short point.

Horizon

The line of sight boundary between the earth and the sky.

Horizontal situation indicator (HSI)

A flight navigation instrument that combines the heading indicator with a CDI, in order to provide the pilot with better situational awareness of location with respect to the courseline.

How Do You Hear Me?

A question relating to the quality of the transmission or to determine how well the transmission is being received.

HSI

Horizontal Situation Indicator.

HUD

Head-Up Display.

Human factors

A multidisciplinary field encompassing the behavioral and social sciences, engineering, and physiology, to consider the variables that influence individual and crew performance for the purpose of optimizing human performance and reducing errors.

Hydroplaning

Hz

Hertz

I Say Again

The message will be repeated.

IAS

Indicated Airspeed.

ICAO

International Civil Aviation Organization.

Icing

The accumulation of airframe ice. Types of icing are: Rime Ice, Clear Ice, Mixed.

Icing Intensity

Trace, Light, Moderate, Severe.

Ident

Air Traffic Control request for a pilot to push the button on the transponder to identify return on the controller’s scope.

Idle thrust

The jet thrust obtained with the engine power control level set at the stop for the least thrust position at which it can be placed.

IFR

Instrument Flight Rules. A set of rules governing the conduct of flight under instrument meteorological conditions.

IFR Conditions

Weather conditions below the minimum for flight under visual flight rules.

IFR Military Training Routes (IR)

Routes used by the Department of Defense and associated Reserve and Air Guard units for the purpose of conducting low-altitude navigation and tactical training in both IFR and VFR weather conditions below 10,000 feet MSL at airspeeds in excess of 250 knots IAS.

IFSD

In-Flight Shutdown.

ILS

Instrument Landing System. A ground based precision approach system that provides course and vertical guidance to landing aircraft.

ILS PRM Approach

An instrument landing system (ILS) approach conducted to parallel runways whose extended centerlines are separated by less than 4,300 feet and the parallel runways have a Precision Runway Monitoring (PRM) system that permits simultaneous independent ILS approaches.

IMC

Instrument Meteorological Conditions

Immediately

Used by ATC or pilots when such action compliance is required to avoid an imminent situation.

Inclinometer

An instrument consisting of a curved glass tube, housing a glass ball, and damped with a fluid similar to kerosene. It may be used to indicate inclination, as a level, or, as used in the turn indicators, to show the relationship between gravity and centrifugal force in a turn.

Increase Speed To (Speed)

Speed Adjustment.

Indicated Airspeed (IAS)

The direct instrument reading obtained from the airspeed indicator, uncorrected for variations in atmospheric density, installation error, or instrument error. Manufacturers use this airspeed as the basis for determining airplane performance. Takeoff, landing, and stall speeds listed in the AFM or POH are indicated airspeeds and do not normally vary with altitude or temperature.

Indicated Altitude

The altitude read directly from the altimeter (uncorrected) when it is set to the current altimeter setting.

Indirect indication

A reflection of aircraft pitch-and-bank attitude by instruments other than the attitude indicator.

Inflight Refueling

Aerial Refueling.

Inflight Weather Advisory

Weather Advisory.

Initial Climb

This stage of the climb begins when the airplane leaves the ground, and a pitch attitude has been established to climb away from the takeoff area.

Instrument

A device using an internal mechanism to show visually or aurally the attitude, altitude, or operation of an aircraft or aircraft part. It includes electronic devices for automatically controlling an aircraft in flight.

Instrument Approach

Instrument Approach Procedure.

Instrument approach procedures (IAP)

A series of predetermined maneuvers for the orderly transfer of an aircraft under IFR from the beginning of the initial approach to a landing or to a point from which a landing may be made visually.

Instrument Departure Procedure (DP)

A preplanned instrument flight rule (IFR) departure procedure published for pilot use, in graphic or textual format, that provides obstruction clearance from the terminal area to the appropriate en route structure. There are two types of DP, Obstacle Departure Procedure (ODP), printed either textually or graphically, and, Standard Instrument Departure (SID), which is always printed graphically.

Instrument Departure Procedure (DP) Charts

Designed to expedite clearance delivery and to facilitate transition between takeoff and en route operations. Each DP is presented as a separate chart and may serve a single airport or more than one airport in a given geographical location.

Instrument flight rules (IFR)

Rules and regulations established by the Federal Aviation Administration to govern flight under conditions in which flight by outside visual reference is not safe. IFR flight depends upon flying by reference to instruments in the flight deck, and navigation is accomplished by reference to electronic signals.

Instrument landing system (ILS)

An electronic system that provides both horizontal and vertical guidance to a specific runway, used to execute a precision instrument approach procedure.

Instrument meteorological conditions (IMC)

Meteorological conditions expressed in terms of visibility, distance from clouds, and ceiling less than the minimums specified for visual meteorological conditions, requiring operations to be conducted under IFR.

INT

Intersection.

Integrated flight instruction

A technique of flight instruction in which students are taught to perform flight maneuvers by reference to both the flight instruments and to outside visual references from the time the maneuver is first introduced. Handling of the controls is the same regardless of whether flight instruments or outside references are being used.

Integrity

The ability of a system to provide timely warnings to users when the system should not be used for navigation.

International Airport

Relating to international flight, it means: a. An airport of entry which has been designated by the Secretary of Treasury or Commissioner of Customs as an international airport for customs service. b. A landing rights airport at which specific permission to land must be obtained from customs authorities in advance of contemplated use. c. Airports designated under the Convention on International Civil Aviation as an airport for use by international commercial air transport and/or international general aviation.

International Civil Aviation Organization [ICAO]

A specialized agency of the United Nations whose objective is to develop the principles and techniques of international air navigation and to foster planning and development of international civil air transport. Regions include: 1. African-Indian Ocean Region 2. Caribbean Region 3. European Region 4. Middle East/Asia Region 5. North American Region 6. North Atlantic Region 7. Pacific Region 8. South American Region

International Flight Information Manual

A publication designed primarily as a pilot’s preflight planning guide for flights into foreign airspace and for flights returning to the U.S. from foreign locations.

International standard atmosphere (IAS)

A model of standard variation of pressure and temperature.

Interpolate

To determine a value in a series between two known values.

Interpolation

The estimation of an intermediate value of a quantity that falls between marked values in a series. Example: In a measurement of length, with a rule that is marked in eighths of an inch, the value falls between 3/8 inch and 1/2 inch. The estimated (interpolated) value might then be said to be 7/16 inch.

Interrogator

The ground-based surveillance radar beacon transmitter-receiver, which normally scans in synchronism with a primary radar, transmitting discrete radio signals which repetitiously request all transponders on the mode being used to reply. The replies received are mixed with the primary radar returns and displayed on the same plan position indicator (radar scope). Also, applied to the airborne element of the TACAN/DME system.

Intersecting Runways

Two or more runways which cross or meet within their lengths.

Intersection

A. A point defined by any combination of courses, radials, or bearings of two or more navigational aids.
B. Used to describe the point where two runways, a runway and a taxiway, or two taxiways cross or meet.

Intersection Departure

A departure from any runway intersection except the end of the runway.

Intersection Takeoff

Intersection Departure.

Inversion

An increase in temperature with altitude.

IR

IFR Military Training Route

ISA (International Standard Atmosphere)

Standard atmospheric conditions consisting of a temperature of 59°F (15°C), and a barometric pressure of 29.92 in. Hg. (1013.2 mb) at sea level. ISA values can be calculated for various altitudes using a standard lapse rate of approximately 2°C per 1,000 feet.

Isogonic lines

Lines drawn across aeronautical charts to connect points having the same magnetic variation.

IVSI

Instantaneous Vertical Speed Indicator.

Jamming

Electronic or mechanical interference which may disrupt the display of aircraft on radar or the transmission/reception of radio communications/navigation.

Jet Blast

Jet engine exhaust (thrust stream turbulence).

Jet Route

A route designed to serve aircraft operations from 18,000 feet MSL up to and including flight level 450. The routes are referred to as “J” routes with numbering to identify the designated route; e.g., J105.

Jet stream

A high-velocity narrow stream of winds, usually found near the upper limit of the troposphere, which flows generally from west to east.

KHz

Kilohertz

KIAS

Knots Indicated Airspeed.

Kite

A framework, covered with paper, cloth, metal, or other material, intended to be flown at the end of a rope or cable, and having as its only support the force of the wind moving past its surfaces.

Knot

A unit of speed equal to one nautical mile per hour.

Known Traffic

With respect to ATC clearances, means aircraft whose altitude, position, and intentions are known to ATC.

Kollsman window

A barometric scale window of a sensitive altimeter used to adjust the altitude for the altimeter setting.

L/MF

Low or Medium Frequency.

LAA

Local Airport Advisory

LAAS

Local Area Augmentation System

Lag

The delay that occurs before an instrument needle attains a stable indication.

LAHSO

Land and Hold Short Operations. Operations which include simultaneous takeoffs and landings and/or simultaneous landings when a landing aircraft is able and is instructed by the controller to hold short of the intersecting runway/taxiway or designated hold-short point. Pilots are expected to promptly inform the controller if the hold short clearance cannot be accepted.

Land And Hold Short Operations

Operations which include simultaneous takeoffs and landings and/or simultaneous landings when a landing aircraft is able and is instructed by the controller to hold-short of the intersecting runway/taxiway or designated hold-short point. Pilots are expected to promptly inform the controller if the hold short clearance cannot be accepted.

Land as soon as possible

Land without delay at the nearest suitable area, such as an open field, at which a safe approach and landing is assured.

Land as soon as practical

The landing site and duration of flight are at the discretion of the pilot. Extended flight beyond the nearest approved landing area is not recommended.

Land immediately

The urgency of the landing is paramount. The primary consideration is to ensure the survival of the occupants. Landing in trees, water, or other unsafe areas should be considered only as a last resort.

Land-Based Air Defense Identification Zone

An ADIZ over U.S. metropolitan areas, which is activated and deactivated as needed, with dimensions, activation dates and other relevant information disseminated via NOTAM. Note: ADIZ locations and operating and flight plan requirements for civil aircraft operations are specified in 14 CFR Part 99.

Landing Area

Any locality either on land, water, or structures, including airports/heliports and intermediate landing fields, which is used, or intended to be used, for the landing and takeoff of aircraft whether or not facilities are provided for the shelter, servicing, or for receiving or discharging passengers or cargo.

Landing Direction Indicator

A device which visually indicates the direction in which landings and takeoffs should be made.

Landing Distance Available (LDA)

The runway length declared available and suitable for a landing airplane.

Landing Minimums

The minimum visibility prescribed for landing a civil aircraft while using an instrument approach procedure. The minimum applies with other limitations set forth in 14 CFR Part 91 with respect to the Minimum Descent Altitude (MDA) or Decision Height (DH) prescribed in the instrument approach procedures as follows: a. Straight-in landing minimums. A statement of MDA and visibility, or DH and visibility, required for a straight-in landing on a specified runway, or b. Circling minimums. A statement of MDA and visibility required for the circle-to-land maneuver. Note: Descent below the established MDA or DH is not authorized during an approach unless the aircraft is in a position from which a normal approach to the runway of intended landing can be made and adequate visual reference to required visual cues is maintained.

Landing Roll

The distance from the point of touchdown to the point where the aircraft can be brought to a stop or exit the runway.

Landing Sequence

The order in which aircraft are positioned for landing.

Large

An Aircraft Class Wake Turbulence Separation Minima. Aircraft of more than 41,000 pounds, maximum certificated takeoff weight, up to but not including 300,000 pounds.

Large Aircraft

An aircraft of more than 12,500 pounds, maximum certificated takeoff weight. As defined in 14 CFR part 1.

Lateral axis

An imaginary line passing through the center of gravity of an airplane and extending across the airplane from wingtip to wingtip.

Lateral Navigation (LNAV)

A function of area navigation (RNAV) equipment which calculates, displays, and provides lateral guidance to a profile or path.

Lateral Separation

The lateral spacing of aircraft at the same altitude by requiring operation on different routes or in different geographical locations.

Latitude

Measurement north or south of the equator in degrees, minutes, and seconds. Lines of latitude are also referred to as parallels.

Leading edge

The part of an airfoil that meets the airflow first.

LFR

Low-Frequency Radio Range.

Licensed empty weight

The empty weight that consists of the airframe, engine(s), unusable fuel, and undrainable oil plus standard and optional equipment as specified in the equipment list. Some manufacturers used this term prior to GAMA standardization.

Lift

A component of the total aerodynamic force on an airfoil and acts perpendicular to the relative wind.

Lift-Off

The act of becoming airborne as a result of the wings lifting the airplane off the ground, or the pilot rotating the nose up, increasing the angle of attack to start a climb.

Light Gun

A handheld directional light signaling device which emits a brilliant narrow beam of white, green, or red light as selected by the tower controller. The color and type of light transmitted can be used to approve or disapprove anticipated pilot actions where radio communication is not available. The light gun is used for controlling traffic operating in the vicinity of the airport and on the airport movement area.

Light Icing

The rate of accumulation may create a problem if flight is prolonged in this environment (over 1 hour). Occasional use of deicing/anti-icing equipment removes/prevents accumulation. It does not present a problem if the deicing/anti-icing equipment is used.

Light-sport aircraft

An aircraft, other than a helicopter or powered-lift that, since its original certification, has continued to meet the following:
(1) A maximum takeoff weight of not more than—
(i) 1,320 pounds (600 kilograms) for aircraft not intended for operation on water; or
(ii) 1,430 pounds (650 kilograms) for an aircraft intended for operation on water.
(2) A maximum airspeed in level flight with maximum continuous power (Vh) of not more than 120 knots CAS under standard atmospheric conditions at sea level.
(3) A maximum never-exceed speed (Vne) of not more than 120 knots CAS for a glider.
(4) A maximum stalling speed or minimum steady flight speed without the use of lift-enhancing devices (Vs1) of not more than 45 knots CAS at the aircraft’s maximum certificated takeoff weight and most critical center of gravity.
(5) A maximum seating capacity of no more than two persons, including the pilot.
(6) A single, reciprocating engine, if powered.
(7) A fixed or ground-adjustable propeller if a powered aircraft other than a powered glider.
(8) A fixed or feathering propeller system if a powered glider.
(9) A fixed-pitch, semi-rigid, teetering, two-blade rotor system, if a gyroplane.
(10) A non-pressurized cabin, if equipped with a cabin.
(11) Fixed landing gear, except for an aircraft intended for operation on water or a glider.
(12) Fixed or retractable landing gear, or a hull, for an aircraft intended for operation on water.
(13) Fixed or retractable landing gear for a glider.

Lighted Airport

An airport where runway and obstruction lighting is available.

Lighter-than-air aircraft

Aircraft that can rise and remain suspended by using contained gas weighing less than the air that is displaced by the gas.

Line Up And Wait (LUAW)

Used by ATC to inform a pilot to taxi onto the departure runway to line up and wait. It is not authorization for takeoff. It is used when takeoff clearance cannot immediately be issued because of traffic or other reasons.

Lines of flux

Invisible lines of magnetic force passing between the poles of a magnet.

LIRL

Low Intensity Runway Lights

LO CIGS

Low Ceilings. Low clouds.

Load factor

The ratio of a specified load to the total weight of the aircraft. The specified load is expressed in terms of any of the following: aerodynamic forces, inertial forces, or ground or water reactions.

LOC

Localizer. The component of an ILS that provides course guidance to the runway.

Local Traffic

Aircraft operating in the traffic pattern or within sight of the tower, or aircraft known to be departing or arriving from flight in local practice areas, or aircraft executing practice instrument approaches at the airport.

Localizer (LOC)

The portion of an ILS that gives left/right guidance information down the centerline of the instrument runway for final approach.

Localizer Usable Distance

The maximum distance from the localizer transmitter at a specified altitude, as verified by flight inspection, at which reliable course information is continuously received.

Long Range Navigation

LORAN. [Decommissioned in 2010]

Long range navigation (LORAN)

[Decommissioned in 2010] An electronic navigational system by which hyperbolic lines of position are determined by measuring the difference in the time of reception of synchronized pulse signals from two fixed transmitters. LORAN-A operates in the 1750–1950 kHz frequency band. LORAN-C and -D operate in the 100–110 kHz frequency band.

Long-range communication system (LRCS)

A system that uses satellite relay, data link, high frequency, or another approved communication system which extends beyond line of sight.

Long-range navigation system (LRNS)

An electronic navigation unit that is approved for use under instrument flight rules as a primary means of navigation, and has at least one source of navigational input, such as inertial navigation system, global positioning system, Omega/very low frequency, or Loran C.

Longitude

Measurement east or west of the Prime Meridian in degrees, minutes, and seconds. The Prime Meridian is 0° longitude and runs through Greenwich, England. Lines of longitude are also referred to as meridians.

Longitudinal Axis

An imaginary line through an aircraft from nose to tail, passing through its center of gravity. The longitudinal axis is also called the roll axis of the aircraft. Movement of the ailerons rotates an airplane about its longitudinal axis.

Longitudinal Stability (Pitching)

Stability about the lateral axis. A desirable characteristic of an airplane whereby it tends to return to its trimmed angle of attack after displacement.

LOP

Line-of-position

LORAN

Long Range Navigation System [Decommissioned in 2010]

Lost Communications

Loss of the ability to communicate by radio. Aircraft are sometimes referred to as NORDO (No Radio). Standard pilot procedures are specified in 14 CFR Part 91. Radar controllers issue procedures for pilots to follow in the event of lost communications during a radar approach when weather reports indicate that an aircraft will likely encounter IFR weather conditions during the approach.

Low Altitude Airway Structure

The network of airways serving aircraft operations up to but not including 18,000 feet MSL.

Low Approach

An approach over an airport or runway following an instrument approach or a VFR approach including the go-around maneuver where the pilot intentionally does not make contact with the runway.

Low Frequency

The frequency band between 30 and 300 kHz.

Low or medium frequency

A frequency range between 190 and 535 kHz with the medium frequency above 300 kHz. Generally associated with nondirectional beacons transmitting a continuous carrier with either a 400 or 1,020 Hz modulation.

LUAW

Line Up and Wait

Lubberline

The reference line used in a magnetic compass or heading indicator.

LZ

Landing Zone

Mach number

The ratio of true airspeed to the speed of sound.

Mach Technique [ICAO]

Describes a control technique used by air traffic control whereby turbojet aircraft operating successively along suitable routes are cleared to maintain appropriate MACH numbers for a relevant portion of the en route phase of flight. The principle objective is to achieve improved utilization of the airspace and to ensure that separation between successive aircraft does not decrease below the established minima.

Magnetic bearing (MB)

The direction to or from a radio transmitting station measured relative to magnetic north.

Magnetic compass

A device for determining direction measured from magnetic north.

Magnetic Course

A predetermined desired course direction to be followed (measured in degrees from local magnetic north).

Magnetic dip

A vertical attraction between a compass needle and the magnetic poles. The closer the aircraft is to a pole, the more severe the effect.

Magnetic heading (MH)

The direction an aircraft is pointed with respect to magnetic north.

Maintain

A. Concerning altitude/flight level, the term means to remain at the altitude/flight level specified. The phrase “climb and” or “descend and” normally precedes “maintain” and the altitude assignment; e.g., “descend and maintain 5,000.”
B. Concerning other ATC instructions, the term is used in its literal sense; e.g., maintain VFR.

Make Short Approach

Used by ATC to inform a pilot to alter his/her traffic pattern so as to make a short final approach.

MALS

Medium Intensity Approach Light System.

MALSR

Medium Intensity Approach Light System with Runway Alignment Indicator Lights.

Man Portable Air Defense Systems (MANPADS)

MANPADS are lightweight, shoulder-launched, missile systems used to bring down aircraft and create mass casualties. The potential for MANPADS use against airborne aircraft is real and requires familiarity with the subject. Terrorists choose MANPADS because the weapons are low cost, highly mobile, require minimal set-up time, and are easy to use and maintain. Although the weapons have limited range, and their accuracy is affected by poor visibility and adverse weather, they can be fired from anywhere on land or from boats where there is unrestricted visibility to the target.

Maneuvering speed (Va)

The maximum speed at which full, abrupt control movement can be used without overstressing the airframe.

MANPADS

Man Portable Air Defense Systems

Mass

The amount of matter in a body.

Maximum weight

The maximum authorized weight of the aircraft and all of its equipment as specified in the Type Certificate Data Sheets (TCDS) for the aircraft.

Mayday

The international radiotelephony distress signal. When repeated three times, it indicates imminent and grave danger and that immediate assistance is requested.

MB

Magnetic Bearing.

Mean sea level

The average height of the surface of the sea at a particular location for all stages of the tide over a 19-year period.

Medical certificate

Acceptable evidence of physical fitness on a form prescribed by the Administrator.

MEL

Minimum Equipment List.

Meridians

Lines of longitude.

METAR

Aviation Routine Weather Report.

Metering Fix

A fix along an established route from over which aircraft will be metered prior to entering terminal airspace. Normally, this fix should be established at a distance from the airport which will facilitate a profile descent 10,000 feet above airport elevation (AAE) or above.

MFD

Multi-Function Display.

MH

Magnetic Heading.

MHz

Megahertz

Middle Compass Locator (LMM)

A compass locator installed at the site of the middle marker of an instrument landing system.

Middle Marker

A marker beacon that defines a point along the glideslope of an ILS normally located at or near the point of decision height (ILS Category I). It is keyed to transmit alternate dots and dashes, with the alternate dots and dashes keyed at the rate of 95 dot/dash combinations per minute on a 1300 Hz tone, which is received aurally and visually by compatible airborne equipment.

Mileage breakdown

A fix indicating a course change that appears on the chart as an “x” at a break between two segments of a federal airway.

Military Landing Zone

A landing strip used exclusively by the military for training. A military landing zone does not carry a runway designation.

Military operations area

A military operations area (MOA) is airspace established outside Class A airspace to separate or segregate certain nonhazardous military activities from IFR Traffic and to identify for VFR traffic where theses activities are conducted.

Military Operations Area (MOA)

A MOA is airspace established outside of Class A airspace area to separate or segregate certain nonhazardous military activities from IFR traffic and to identify for VFR traffic where these activities are conducted.

Military training route (MTR)

Airspace of defined vertical and lateral dimensions established for the conduct of military training at airspeeds in excess of 250 knots indicated airspeed (KIAS).

Minima

Minimums.

Minimum Fuel

Indicates that an aircraft’s fuel supply has reached a state where, upon reaching the destination, it can accept little or no delay. This is not an emergency situation but merely indicates an emergency situation is possible should any undue delay occur.

Minimum Holding Altitude

The lowest altitude prescribed for a holding pattern which assures navigational signal coverage, communications, and meets obstacle clearance requirements.

Minimum Safe Altitude Warning

A function of the ARTS III computer that aids the controller by alerting him/her when a tracked Mode C equipped aircraft is below or is predicted by the computer to go below a predetermined minimum safe altitude.

Minimum Vectoring Altitude (MVA)

The lowest MSL altitude at which an IFR aircraft will be vectored by a radar controller, except as otherwise authorized for radar approaches, departures, and missed approaches. The altitude meets IFR obstacle clearance criteria. It may be lower than the published MEA along an airway or J-route segment. It may be utilized for radar vectoring only upon the controller’s determination that an adequate radar return is being received from the aircraft being controlled. Charts depicting minimum vectoring altitudes are normally available only to the controllers and not to pilots.

Minimums

Weather condition requirements established for a particular operation or type of operation; e.g., IFR takeoff or landing, alternate airport for IFR flight plans, VFR flight, etc.

MIRL

Medium Intensity Runway Lights

Missed Approach

A. A maneuver conducted by a pilot when an instrument approach cannot be completed to a landing. The route of flight and altitude are shown on instrument approach procedure charts. A pilot executing a missed approach prior to the Missed Approach Point (MAP) must continue along the final approach to the MAP.
B. A term used by the pilot to inform ATC that he/she is executing the missed approach.
C. At locations where ATC radar service is provided, the pilot should conform to radar vectors when provided by ATC in lieu of the published missed approach procedure.

Missed Approach

The segment between the missed approach point or the point of arrival at decision height and the missed approach fix at the prescribed altitude.

MOA

Military Operations Area

Mode

The letter or number assigned to a specific pulse spacing of radio signals transmitted or received by ground interrogator or airborne transponder components of the Air Traffic Control Radar Beacon System (ATCRBS). Mode A (military Mode 3) and Mode C (altitude reporting) are used in air traffic control.

Mode C

Altitude reporting transponder mode.

Moderate Icing

The rate of accumulation is such that even short encounters become potentially hazardous and use of deicing/anti-icing equipment or flight diversion is necessary.

Modified T

An RNAV approach design for single or multiple runways where terrain or operational constraints do not allow for the standard T. The “T” may be modified by increasing or decreasing the angle from the corner IAF(s) to the IF or by eliminating one or both corner IAFs.

Monitor

(When used with communication transfer) listen on a specific frequency and stand by for instructions. Under normal circumstances do not establish communications.

Movement Area

The runways, taxiways, and other areas of an airport/heliport which are utilized for taxiing/hover taxiing, air taxiing, takeoff, and landing of aircraft, exclusive of loading ramps and parking areas. At those airports/heliports with a tower, specific approval for entry onto the movement area must be obtained from ATC.

Moving Target Indicator

A digital moving target indicator (MTI) radar system for rejection of low velocity "clutter" by utilizing techniques to identify those radar echo returns from targets having radial velocities lower than fixed predetermined values.

MRB

Magnetic Reference Bearing

MSL

Mean Sea Level.

MSL Altitude

Altitude expressed in feet measured from mean sea level.

MTI

Moving Target Indicator

MTR

Military Training Route

Multicom

A mobile service not open to public correspondence used to provide communications essential to conduct the activities being performed by or directed from private aircraft.

Multiple Runways

The utilization of a dedicated arrival runway(s) for departures and a dedicated departure runway(s) for arrivals when feasible to reduce delays and enhance capacity.

Mushing

A flight condition caused by slow speed where the control surfaces are marginally effective.

MWO

Meteorological Watch Office

NACG

National Aeronautical Charting Group. (obsolete)

NACO

National Aeronautical Charting Office

NAS

National Airspace System. The common network of U.S. airspace; air navigation facilities, equipment and services, airports or landing areas.

NASA

National Aeronautics and Space Administration

NATCA

National Air Traffic Controllers Association

National Aeronautical Charting Group (NACG)

A Federal agency operating under the FAA, responsible for publishing charts such as the terminal procedures and en route charts. Moved to Aeronautical Information Services AJV-A

National Airspace System

The common network of U.S. airspace; air navigation facilities, equipment and services, airports or landing areas; aeronautical charts, information and services; rules, regulations and procedures, technical information, and manpower and material. Included are system components shared jointly with the military.

National Airspace System (NAS)

The common network of United States airspace—air navigation facilities, equipment and services, airports or landing areas; aeronautical charts, information and services; rules, regulations and procedures, technical information; and manpower and material.

National defense airspace

Airspace established by a regulation prescribed, or an order issued under, 49 U.S.C. 40103(b)(3).

National Flight Data Center

A facility in Washington D.C., established by FAA to operate a central aeronautical information service for the collection, validation, and dissemination of aeronautical data in support of the activities of government, industry, and the aviation community. The information is published in the National Flight Data Digest.

National Flight Data Digest

A daily (except weekends and Federal holidays) publication of flight information appropriate to aeronautical charts, aeronautical publications, Notices to Airmen, or other media serving the purpose of providing operational flight data essential to safe and efficient aircraft operations.

National Route Program (NRP)

A set of rules and procedures designed to increase the flexibility of user flight planning within published guidelines.

National Security Area (NSA)

Areas consisting of airspace of defined vertical and lateral dimensions established at locations where there is a requirement for increased security and safety of ground facilities. Pilots are requested to voluntarily avoid flying through the depicted NSA. When it is necessary to provide a greater level of security and safety, flight in NSAs may be temporarily prohibited. Regulatory prohibitions are disseminated via NOTAMs.

National Transportation Safety Board (NTSB)

A United States Government independent organization responsible for investigations of accidents involving aviation, highways, waterways, pipelines, and railroads in the United States. NTSB is charged by congress to investigate every civil aviation accident in the United States.

NAV/COM

Navigation and communication radio.

NAVAID

Navigational Aid. Any visual or electronic device, airborne or on the surface, which provides point-to-point guidance information or position data to aircraft in flight.

Navaid Classes

VOR, VORTAC, and TACAN aids are classed according to their operational use. The three classes of NAVAIDs are: a. T-Terminal. b. L-Low altitude. c. H-High altitude. Note: The normal service range for T, L, and H class aids is found in the AIM. Certain operational requirements make it necessary to use some of these aids at greater service ranges than specified. Extended range is made possible through flight inspection determinations. Some aids also have lesser service range due to location, terrain, frequency protection, etc. Restrictions to service range are listed in Airport/Facility Directory.

Navigable Airspace

Airspace at and above the minimum flight altitudes prescribed in the CFRs including airspace needed for safe takeoff and landing.

Navigational Aid

Any visual or electronic device airborne or on the surface which provides point-to-point guidance information or position data to aircraft in flight.

NDB

Nondirectional Radio Beacon

NDB (ADF)

Nondirectional Beacon (Automatic Direction Finder).

Negative

“No,” or “permission not granted,” or “that is not correct.”

Negative Contact

Used by pilots to inform ATC that: a. Previously issued traffic is not in sight. It may be followed by the pilot’s request for the controller to provide assistance in avoiding the traffic. b. They were unable to contact ATC on a particular frequency.

NFDC

National Flight Data Center

NGA

National Geospatial-Intelligence Agency

Night

The time between the end of evening civil twilight and the beginning of morning civil twilight, as published in the American Air Almanac, converted to local time.

NM

Nautical Mile. International unit equal to 6076.115 feet (1852 meters).

No Gyro Approach

A radar approach/vector provided in case of a malfunctioning gyro-compass or directional gyro. Instead of providing the pilot with headings to be flown, the controller observes the radar track and issues control instructions “turn right/left” or “stop turn” as appropriate.

No Gyro Vector

No Gyro Approach. A radar approach/vector provided in case of a malfunctioning gyro-compass or directional gyro. Instead of providing the pilot with headings to be flown, the controller observes the radar track and issues control instructions “turn right/left” or “stop turn” as appropriate.

No Transgression Zone (NTZ)

The NTZ is a 2,000 foot wide zone, located equidistant between parallel runway final approach courses in which flight is not allowed.

NOAA

National Oceanic and Atmospheric Administration

Nonapproach Control Tower

Authorizes aircraft to land or takeoff at the airport controlled by the tower or to transit the Class D airspace. The primary function of a nonapproach control tower is the sequencing of aircraft in the traffic pattern and on the landing area. Nonapproach control towers also separate aircraft operating under instrument flight rules clearances from approach controls and centers. They provide ground control services to aircraft, vehicles, personnel, and equipment on the airport movement area.

Nonmovement Areas

Taxiways and apron (ramp) areas not under the control of air traffic.

NORDO

(No Radio) Aircraft That Cannot Or Do Not Communicate By Radio When Radio Communication Is Required Are Referred To As “Nordo.

Normal Category

A category of aircraft certificated under 14 CFR part 23 and CAR part 3 that allows the maximum weight and CG range while restricting the maneuvers that are permitted.

NOTAM

Notice to Airmen. A notice containing information (not known sufficiently in advance to publicize by other means) concerning the establishment, condition, or change in any component (facility, service, or procedure of, or hazard in the National Airspace System) the timely knowledge of which is essential to personnel concerned with flight operations.

NOTAM D

Distant Notam

NOTAM L

Local Notam

Notice To Airmen

A notice containing information (not known sufficiently in advance to publicize by other means) concerning the establishment, condition, or change in any component (facility, service, or procedure of, or hazard in the National Airspace System) the timely knowledge of which is essential to personnel concerned with flight operations. There are two types: NOTAM(D) and FDC NOTAM.

Notices To Airmen Publication

A publication issued every 28 days, designed primarily for the pilot, which contains current NOTAM information considered essential to the safety of flight as well as supplemental data to other aeronautical publications. The contraction NTAP is used in NOTAM text.

NPRM

Notice of Proposed Rulemaking

NRP

North American Route Program. The NRP is a set of rules and procedures which are designed to increase the flexibility of user flight planning within published guidelines.

NSA

National Security Area

NTAP

Notices to Airmen Publication

NTSB

National Transportation Safety Board

NTZ

No Transgression Zone

Numerous Targets Vicinity (Location)

A traffic advisory issued by ATC to advise pilots that targets on the radar scope are too numerous to issue individually.

NWS

National Weather Service.

OAT

Outside Air Temperature

OBS

Omni-bearing Selector

Obstacle

An existing object, object of natural growth, or terrain at a fixed geographical location or which may be expected at a fixed location within a prescribed area with reference to which vertical clearance is or must be provided during flight operation.

Obstacle Free Zone

The OFZ is a three dimensional volume of airspace which protects for the transition of aircraft to and from the runway. The OFZ clearing standard precludes taxiing and parked airplanes and object penetrations, except for frangible NAVAID locations that are fixed by function. Additionally, vehicles, equipment, and personnel may be authorized by air traffic control to enter the area using the provisions of FAAO JO 7110.65, Para 3-1-5, VEHICLES/EQUIPMENT/PERSONNEL ON RUNWAYS. The runway OFZ and when applicable, the inner-approach OFZ, and the inner-transitional OFZ, comprise the OFZ.

Obstruction

Any object/obstacle exceeding the obstruction standards specified by 14 CFR Part 77, Subpart C.

Obstruction lights

Lights that can be found both on and off an airport to identify obstructions.

Offset Parallel Runways

Staggered runways having centerlines which are parallel.

On Course

A. Used to indicate that an aircraft is established on the route centerline.
B. Used by ATC to advise a pilot making a radar approach that his/her aircraft is lined up on the final approach course.

On-Course Indication

An indication on an instrument, which provides the pilot a visual means of determining that the aircraft is located on the centerline of a given navigational track, or an indication on a radar scope that an aircraft is on a given track.

One-Minute Weather

The most recent one minute updated weather broadcast received by a pilot from an uncontrolled airport ASOS/AWSS/AWOS.

Operate

With respect to aircraft, use, cause to use or authorize to use aircraft, for the purpose (except as provided in §91.13 of this chapter) of air navigation including the piloting of aircraft, with or without the right of legal control (as owner, lessee, or otherwise).

Operational control

With respect to a flight, the exercise of authority over initiating, conducting or terminating a flight.

Opposite Direction Aircraft

Aircraft are operating in opposite directions when: a. They are following the same track in reciprocal directions; or b. Their tracks are parallel and the aircraft are flying in reciprocal directions; or c. Their tracks intersect at an angle of more than 135°.

Option Approach

An approach requested and conducted by a pilot which will result in either a touch-and-go, missed approach, low approach, stop-and-go, or full stop landing.

OTS

Out of service

Out

The conversation is ended and no response is expected.

Outer Area (Associated With Class C Airspace)

Nonregulatory airspace surrounding designated Class C airspace airports wherein ATC provides radar vectoring and sequencing on a full-time basis for all IFR and participating VFR aircraft. The service provided in the outer area is called Class C service which includes: IFR/IFR-standard IFR separation; IFR/VFR-traffic advisories and conflict resolution; and VFR/VFR-traffic advisories and, as appropriate, safety alerts. The normal radius will be 20 nautical miles with some variations based on site-specific requirements. The outer area extends outward from the primary Class C airspace airport and extends from the lower limits of radar/radio coverage up to the ceiling of the approach control’s delegated airspace excluding the Class C charted area and other airspace as appropriate.

Outer Marker

A marker beacon at or near the glideslope intercept altitude of an ILS approach. It is keyed to transmit two dashes per second on a 400 Hz tone, which is received aurally and visually by compatible airborne equipment. The OM is normally located four to seven miles from the runway threshold on the extended centerline of the runway.

Over

My transmission is ended; I expect a response.

Over-the-top

Above the layer of clouds or other obscuring phenomena forming the ceiling.

Overcontrolling

Using more movement in the control column than is necessary to achieve the desired pitch-and-bank condition.

Overpower

To use more power than required for the purpose of achieving a faster rate of airspeed change.

P Time

Proposed Departure Time.

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.

P-static

Precipitation Static.

P/CG

Pilot/Controller Glossary

Pan-Pan

The international radio-telephony urgency signal. When repeated three times, indicates uncertainty or alert followed by the nature of the urgency.

PAPI

Precision Approach Path Indicator

Parachute

A device used or intended to be used to retard the fall of a body or object through the air.

Parallel Offset Route

A parallel track to the left or right of the designated or established airway/route. Normally associated with Area Navigation (RNAV) operations.

Parallel Runways

Two or more runways at the same airport whose centerlines are parallel. In addition to runway number, parallel runways are designated as L (left) and R (right) or, if three parallel runways exist, L (left), C (center), and R (right).

Parallels

Lines of latitude.

Parasite drag

Drag caused by the friction of air moving over the aircraft structure; its amount varies directly with the airspeed.

PAX

Passengers.

Payload (GAMA)

The weight of occupants, cargo, and baggage.

Permanent Echo

Radar signals reflected from fixed objects on the earth’s surface; e.g., buildings, towers, terrain. Permanent echoes are distinguished from “ground clutter” by being definable locations rather than large areas. Under certain conditions they may be used to check radar alignment.

Person

An individual, firm, partnership, corporation, company, association, joint-stock association, or governmental entity. It includes a trustee, receiver, assignee, or similar representative of any of them.

Personal computer-based aviation training device (PCATD)

A device which uses software which can be displayed on a personal computer to replicate the instrument panel of an airplane. A PCATD must replicate a type of airplane or family of airplanes and meet the virtual control requirements specified in AC 61-126.

PFD

Primary Flight Display

PFD

Personal Flotation Device

PIC

Pilot In Command.

Pilot Briefing

A service provided by the FSS to assist pilots in flight planning. Briefing items may include weather information, NOTAMs, military activities, flow control information, and other items as requested.

Pilot in command

The person who:
(1) Has final authority and responsibility for the operation and safety of the flight;
(2) Has been designated as pilot in command before or during the flight; and
(3) Holds the appropriate category, class, and type rating, if appropriate, for the conduct of the flight.

Pilot In Command

The pilot responsible for the operation and safety of an aircraft during flight time.

Pilotage

Navigation by visual reference to landmarks.

Pilot’s Discretion

When used in conjunction with altitude assignments, means that ATC has offered the pilot the option of starting climb or descent whenever he/she wishes and conducting the climb or descent at any rate he/she wishes. He/she may temporarily level off at any intermediate altitude. However, once he/she has vacated an altitude, he/she may not return to that altitude.

Pilot’s Operating Handbook/Airplane Flight Manual (POH/AFM)

FAA-approved documents published by the airframe manufacturer that list the operating conditions for a particular model of aircraft.

PinS

Point-in-Space

PIREP

Pilot Report.

Pirep

Pilot Weather Report.

Pitch

The rotation of an airplane about its lateral axis, or on a propeller, the blade angle as measured from plane of rotation.

Pitch setting

The propeller blade setting as determined by the blade angle measured in a manner, and at a radius, specified by the instruction manual for the propeller.

Pitot pressure

Ram air pressure used to measure airspeed.

Pitot-static head

A combination pickup used to sample pitot pressure and static air pressure.

PMA

Parts Manufacturer Approval.

POB

Persons on Board

POFZ

Precision Obstacle Free Zone

POH

Pilots Operating Handbook

POH/AFM

Pilot’s Operating Handbook/Airplane Flight Manual.

Position error

Error in the indication of the altimeter, ASI, and VSI caused by the air at the static system entrance not being absolutely still.

Position report

A report over a known location as transmitted by an aircraft to ATC.

Positive Control

The separation of all air traffic within designated airspace by air traffic control.

Positive static stability

The initial tendency to return to a state of equilibrium when disturbed from that state.

Powered parachute

A powered aircraft comprised of a flexible or semi-rigid wing connected to a fuselage so that the wing is not in position for flight until the aircraft is in motion. The fuselage of a powered parachute contains the aircraft engine, a seat for each occupant and is attached to the aircraft’s landing gear.

Powered-lift

A heavier-than-air aircraft capable of vertical takeoff, vertical landing, and low speed flight that depends principally on engine-driven lift devices or engine thrust for lift during these flight regimes and on nonrotating airfoil(s) for lift during horizontal flight.

PPS

Precise Positioning Service

Practical Test Standards (PTS)

An FAA published list of standards which must be met for the issuance of a particular pilot certificate or rating. FAA inspectors and designated pilot examiners use these standards when conducting pilot practical tests and flight instructors should use the PTS while preparing applicants for practical tests. (Obsolete term, replaced by Airman Certification Standards)

Practice Instrument Approach

An instrument approach procedure conducted by a VFR or an IFR aircraft for the purpose of pilot training or proficiency demonstrations.

Pre-Departure Clearance

An application with the Terminal Data Link System (TDLS) that provides clearance information to subscribers, through a service provider, in text to the cockpit or gate printer.

Pre-Flight Pilot Briefing

Pilot Briefing.

Precession

The characteristic of a gyroscope that causes an applied force to be felt, not at the point of application, but 90° from that point in the direction of rotation.

Precipitation Radar Weather Descriptions

Existing radar systems cannot detect turbulence. However, there is a direct correlation between the degree of turbulence and other weather features associated with thunderstorms and the weather radar precipitation intensity. Controllers will issue (where capable) precipitation intensity as observed by radar when using weather and radar processor (WARP) or NAS ground based digital radars with weather capabilities. When precipitation intensity information is not available, the intensity will be described as UNKNOWN. When intensity levels can be determined, they shall be described as: a. LIGHT (< 30 dBZ b. MODERATE (30 to 40 dBZ c. HEAVY (> 40 to 50 dBZ d. EXTREME (> 50 dBZ

Precision Approach

Precision Approach Procedure.

Precision Approach Path Indicator (PAPI)

An airport lighting facility, similar to VASI, providing vertical approach slope guidance to aircraft during approach to landing. PAPIs consist of a single row of either two or four lights, normally installed on the left side of the runway, and have an effective visual range of about 5 miles during the day and up to 20 miles at night. PAPIs radiate a directional pattern of high intensity red and white focused light beams which indicate that the pilot is “on path” if the pilot sees an equal number of white lights and red lights, with white to the left of the red; “above path” if the pilot sees more white than red lights; and “below path” if the pilot sees more red than white lights.

Precision Approach Runway, Category I

An instrument runway served by ILS and visual aids intended for operations down to 60 m (200 feet) decision height and down to an RVR of the order of 800 m.

Precision Approach Runway, Category II

An instrument runway served by ILS and visual aids intended for operations down to 30 m (100 feet) decision height and down to an RVR of the order of 400 m.

Precision Approach Runway, Category III

An instrument runway served by ILS to and along the surface of the runway and: 1. Intended for operations down to an RVR of the order of 200 m (no decision height being applicable) using visual aids during the final phase of landing; 2. Intended for operations down to an RVR of the order of 50 m (no decision height being applicable) using visual aids for taxiing; 3. Intended for operations without reliance on visual reference for landing or taxiing. Note: Visual aids need not necessarily be matched to the scale of nonvisual aids provided. The criterion for the selection of visual aids is the conditions in which operations are intended to be conducted.

Precision Obstacle Free Zone (POFZ)

An 800 foot wide by 200 foot long area centered on the runway centerline adjacent to the threshold designed to protect aircraft flying precision approaches from ground vehicles and other aircraft when ceiling is less than 250 feet or visibility is less than 3/4 statute mile (or runway visual range below 4,000 feet.

Predictive Wind Shear Alert System (PWS)

A self-contained system used onboard some aircraft to alert the flight crew to the presence of a potential wind shear. PWS systems typically monitor 3 miles ahead and 25 degrees left and right of the aircraft’s heading at or below 1200’ AGL. Departing flights may receive a wind shear alert after they start the takeoff roll and may elect to abort the takeoff. Aircraft on approach receiving an alert may elect to go around or perform a wind shear escape maneuver.

Preferential Arrival Route PAR

A specific arrival route from an appropriate en route point to an airport or terminal area. It may be included in a Standard Terminal Arrival (STAR) or a Preferred IFR Route. The abbreviation “PAR” is used primarily within the ARTCC and should not be confused with the abbreviation for Precision Approach Radar.

Preferential Departure And Arrival Route (PDAR)

A route between two terminals which are within or immediately adjacent to one ARTCC’s area. PDARs are not synonymous with Preferred IFR Routes but may be listed as such as they do accomplish essentially the same purpose.

Preferential Departure Route (PDR)

A specific departure route from an airport or terminal area to an en route point where there is no further need for flow control. It may be included in an Instrument Departure Procedure (DP) or a Preferred IFR Route.

Preferential Routes

Preferential routes (PDRs, PARs, and PDARs) are adapted in ARTCC computers to accomplish inter/intrafacility controller coordination and to assure that flight data is posted at the proper control positions. Locations having a need for these specific inbound and outbound routes normally publish such routes in local facility bulletins, and their use by pilots minimizes flight plan route amendments. When the workload or traffic situation permits, controllers normally provide radar vectors or assign requested routes to minimize circuitous routing. Preferential routes are usually confined to one ARTCC’s area and are referred to by the following names or acronyms: Preferential Departure Route (PDR), Preferential Arrival Route (PAR), and Preferential Departure and Arrival Route (PDAR).

Preferred IFR Routes

Routes established between busier airports to increase system efficiency and capacity. They normally extend through one or more ARTCC areas and are designed to achieve balanced traffic flows among high density terminals. IFR clearances are issued on the basis of these routes except when severe weather avoidance procedures or other factors dictate otherwise. Preferred IFR Routes are listed in the Airport/Facility Directory. If a flight is planned to or from an area having such routes but the departure or arrival point is not listed in the Airport/Facility Directory, pilots may use that part of a Preferred IFR Route which is appropriate for the departure or arrival point that is listed. Preferred IFR Routes are correlated with DPs and STARs and may be defined by airways, jet routes, direct routes between NAVAIDs, Waypoints, NAVAID radials/DME, or any combinations thereof.

Pressure Altitude

The altitude indicated when the altimeter setting window (barometric scale) is adjusted to 29.92. This is the altitude above the standard datum plane, which is a theoretical plane where air pressure (corrected to 15ºC) equals 29.92 in. Hg. Pressure altitude is used to compute density altitude, true altitude, true airspeed, and other performance data.

Prevailing Visibility

The greatest horizontal visibility equaled or exceeded throughout at least half the horizon circle which need not necessarily be continuous.

Primary Radar

A radar system in which a minute portion of a radio pulse transmitted from a site is reflected by an object and then received back at that site for processing and display at an air traffic control facility.

Progressive Taxi

Precise taxi instructions given to a pilot unfamiliar with the airport or issued in stages as the aircraft proceeds along the taxi route.

Prominent Obstacle

An obstacle that meets one or more of the following conditions: a. An obstacle which stands out beyond the adjacent surface of surrounding terrain and immediately projects a noticeable hazard to aircraft in flight. b. An obstacle, not characterized as low and close in, whose height is no less than 300 feet above the departure end of takeoff runway (DER) elevation, is within 10NM from the DER, and that penetrates that airport/heliport’s diverse departure obstacle clearance surface (OCS). c. An obstacle beyond 10NM from an airport/heliport that requires an obstacle departure procedure (ODP) to ensure obstacle avoidance.

Propeller

A device for propelling an aircraft that has blades on an engine-driven shaft and that, when rotated, produces by its action on the air, a thrust approximately perpendicular to its plane of rotation. It includes control components normally supplied by its manufacturer, but does not include main and auxiliary rotors or rotating airfoils of engines.

Proposed Departure Time

The time that the aircraft expects to become airborne.

PT

Procedure Turn

PTRS

Performance Tracking and Reporting System.

PTS

Practical Test Standards. (Obsolete term, replaced by Airman Certification Standards–ACS)

Public aircraft

Any of the following aircraft when not being used for a commercial purpose or to carry an individual other than a crewmember or qualified non-crewmember:
(1) An aircraft used only for the United States Government; an aircraft owned by the Government and operated by any person for purposes related to crew training, equipment development, or demonstration; an aircraft owned and operated by the government of a State, the District of Columbia, or a territory or possession of the United States or a political subdivision of one of these governments; or an aircraft exclusively leased for at least 90 continuous days by the government of a State, the District of Columbia, or a territory or possession of the United States or a political subdivision of one of these governments.
(i) For the sole purpose of determining public aircraft status, commercial purposes means the transportation of persons or property for compensation or hire, but does not include the operation of an aircraft by the armed forces for reimbursement when that reimbursement is required by any Federal statute, regulation, or directive, in effect on November 1, 1999, or by one government on behalf of another government under a cost reimbursement agreement if the government on whose behalf the operation is conducted certifies to the Administrator of the Federal Aviation Administration that the operation is necessary to respond to a significant and imminent threat to life or property (including natural resources) and that no service by a private operator is reasonably available to meet the threat.
(ii) For the sole purpose of determining public aircraft status, governmental function means an activity undertaken by a government, such as national defense, intelligence missions, firefighting, search and rescue, law enforcement (including transport of prisoners, detainees, and illegal aliens), aeronautical research, or biological or geological resource management.
(iii) For the sole purpose of determining public aircraft status, qualified non-crewmember means an individual, other than a member of the crew, aboard an aircraft operated by the armed forces or an intelligence agency of the United States Government, or whose presence is required to perform, or is associated with the performance of, a governmental function.
(2) An aircraft owned or operated by the armed forces or chartered to provide transportation to the armed forces if—
(i) The aircraft is operated in accordance with title 10 of the United States Code;
(ii) The aircraft is operated in the performance of a governmental function under title 14, 31, 32, or 50 of the United States Code and the aircraft is not used for commercial purposes; or
(iii) The aircraft is chartered to provide transportation to the armed forces and the Secretary of Defense (or the Secretary of the department in which the Coast Guard is operating) designates the operation of the aircraft as being required in the national interest.
(3) An aircraft owned or operated by the National Guard of a State, the District of Columbia, or any territory or possession of the United States, and that meets the criteria of paragraph (2) of this definition, qualifies as a public aircraft only to the extent that it is operated under the direct control of the Department of Defense.

QICP

Qualified Internet Communications Provider

Radar

A system that uses electromagnetic waves to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, weather formations, and terrain. The term RADAR was coined in 1941 as an acronym for Radio Detection and Ranging. The term has since entered the English language as a standard word, radar, losing the capitalization in the process.

Radar Approach Control Facility

A terminal ATC facility that uses radar and nonradar capabilities to provide approach control services to aircraft arriving, departing, or transiting airspace controlled by the facility. a. Provides radar ATC services to aircraft operating in the vicinity of one or more civil and/or military airports in a terminal area. The facility may provide services of a ground controlled approach (GCA); i.e., ASR and PAR approaches. A radar approach control facility may be operated by FAA, USAF, US Army, USN, USMC, or jointly by FAA and a military service. Specific facility nomenclatures are used for administrative purposes only and are related to the physical location of the facility and the operating service generally as follows: 1. Army Radar Approach Control (ARAC) (Army). 2. Radar Air Traffic Control Facility (RATCF) (Navy/FAA). 3. Radar Approach Control (RAPCON) (Air Force/FAA). 4. Terminal Radar Approach Control (TRACON) (FAA). 5. Air Traffic Control Tower (ATCT) (FAA). (Only those towers delegated approach control authority.

Radar Contact

A. Used by ATC to inform an aircraft that it is identified on the radar display and radar flight following will be provided until radar identification is terminated. Radar service may also be provided within the limits of necessity and capability. When a pilot is informed of “radar contact,” he/she automatically discontinues reporting over compulsory reporting points.
B. The term used to inform the controller that the aircraft is identified and approval is granted for the aircraft to enter the receiving controllers airspace.

Radar Contact Lost

Used by ATC to inform a pilot that radar data used to determine the aircraft’s position is no longer being received, or is no longer reliable and radar service is no longer being provided. The loss may be attributed to several factors including the aircraft merging with weather or ground clutter, the aircraft operating below radar line of sight coverage, the aircraft entering an area of poor radar return, failure of the aircraft transponder, or failure of the ground radar equipment.

Radar Environment

An area in which radar service may be provided.

Radar Flight Following

The observation of the progress of radar identified aircraft, whose primary navigation is being provided by the pilot, wherein the controller retains and correlates the aircraft identity with the appropriate target or target symbol displayed on the radar scope.

Radar Identification

The process of ascertaining that an observed radar target is the radar return from a particular aircraft.

Radar Identified Aircraft

An aircraft, the position of which has been correlated with an observed target or symbol on the radar display.

Radar Monitoring

The radar flight-following of aircraft, whose primary navigation is being performed by the pilot, to observe and note deviations from its authorized flight path, airway, or route. When being applied specifically to radar monitoring of instrument approaches; i.e., with precision approach radar (PAR) or radar monitoring of simultaneous ILS/MLS approaches, it includes advice and instructions whenever an aircraft nears or exceeds the prescribed PAR safety limit or simultaneous ILS/MLS no transgression zone.

Radar Service

A term which encompasses one or more of the following services based on the use of radar which can be provided by a controller to a pilot of a radar identified aircraft: Radar Monitoring, Radar Navigational Guidance, and Radar Separation.

Radar Service Terminated

Used by ATC to inform a pilot that he/she will no longer be provided any of the services that could be received while in radar contact. Radar service is automatically terminated, and the pilot is not advised in the following cases: a. An aircraft cancels its IFR flight plan, except within Class B airspace, Class C airspace, a TRSA, or where Basic Radar service is provided. b. An aircraft conducting an instrument, visual, or contact approach has landed or has been instructed to change to advisory frequency. c. An arriving VFR aircraft, receiving radar service to a tower-controlled airport within Class B airspace, Class C airspace, a TRSA, or where sequencing service is provided, has landed; or to all other airports, is instructed to change to tower or advisory frequency. d. An aircraft completes a radar approach.

Radar Surveillance

The radar observation of a given geographical area for the purpose of performing some radar function.

Radar Traffic Advisories

Advisories issued to alert pilots to known or observed radar traffic which may affect the intended route of flight of their aircraft.

Radial

A magnetic bearing extending from a VOR/VORTAC/TACAN navigation facility.

Radio

A device used for communication.

Radio

Used to refer to a flight service station; e.g., “Seattle Radio” is used to call Seattle FSS.

Radio frequency (RF)

A term that refers to alternating current (AC) having characteristics such that, if the current is input to antenna, an electromagnetic (EM) field is generated suitable for wireless broadcasting and/or communications.

Radio magnetic indicator (RMI)

An electronic navigation instrument that combines a magnetic compass with an ADF or VOR. The card of the RMI acts as a gyro-stabilized magnetic compass, and shows the magnetic heading the aircraft is flying.

Radio or radar altimeter

An electronic altimeter that determines the height of an aircraft above the terrain by measuring the time needed for a pulse of radio-frequency energy to travel from the aircraft to the ground and return.

Radio wave

An electromagnetic (EM ) wave with frequency characteristics useful for radio transmission.

RAIM

Receiver Autonomous Integrity Monitoring

RAIS

Remote Airport Information Service

Ramp

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.

Random RNAV routes

Direct routes, based on area navigation capability, between waypoints defined in terms of latitude/longitude coordinates, degree-distance fixes, or offsets from established routes/airways at a specified distance and direction.

Random Route

Any route not established or charted/published or not otherwise available to all users.

Ranging signals

Transmitted from the GPS satellite, signals allowing the aircraft’s receiver to determine range (distance) from each satellite.

Rate Of Turn

The rate in degrees/second of a turn.

Rated maximum continuous power

With respect to reciprocating, turbopropeller, and turboshaft engines, the approved brake horsepower that is developed statically or in flight, in standard atmosphere at a specified altitude, within the engine operating limitations established under Part 33, and approved for unrestricted periods of use.

Rated takeoff power

With respect to reciprocating, turbopropeller, and turboshaft engine type certification, the approved brake horsepower that is developed statically under standard sea level conditions, within the engine operating limitations established under Part 33, and limited in use to periods of not over 5 minutes for takeoff operation.

Rating

A statement that, as a part of a certificate, sets forth special conditions, privileges, or limitations.

RB

Relative Bearing.

RBI

Relative Bearing Indicator.

RBN

Radio Beacon.

RCAG

Remote Center Air/Ground

RCC

Rescue Coordination Center

RCLM

Runway Centerline Marking.

RCLS

Runway Centerline Lighting System

RCO

Remote Communications Outlet

Read Back

Repeat my message back to me.

Receiver autonomous integrity monitoring (RAIM)

A system used to verify the usability of the received GPS signals and warns the pilot of any malfunction in the navigation system. This system is required for IFR-certified GPS units.

Receiver-transmitter (RT)

A system that receives and transmits a signal and an indicator.

Reduce Speed To (Speed)

Speed Adjustment.

Reference landing speed

The speed of the airplane, in a specified landing configuration, at the point where it descends through the 50 foot height in the determination of the landing distance.

Region of reverse command

Flight regime in which flight at a higher airspeed requires a lower power setting and a lower airspeed requires a higher power setting in order to maintain altitude.

Regions of command

The “regions of normal and reversed command” refers to the relationship between speed and the power required to maintain or change that speed in flight.

REIL

Runway End Identifier Lights

Remote Communications Outlet

An unmanned communications facility remotely controlled by air traffic personnel. RCOs serve FSSs. RTRs serve terminal ATC facilities. An RCO or RTR may be UHF or VHF and will extend the communication range of the air traffic facility. There are several classes of RCOs and RTRs. The class is determined by the number of transmitters or receivers. Classes A through G are used primarily for air/ground purposes. RCO and RTR class O facilities are nonprotected outlets subject to undetected and prolonged outages. RCO (O’s) and RTR (O’s) were established for the express purpose of providing ground-to-ground communications between air traffic control specialists and pilots located at a satellite airport for delivering en route clearances, issuing departure authorizations, and acknowledging instrument flight rules cancellations or departure/landing times. As a secondary function, they may be used for advisory purposes whenever the aircraft is below the coverage of the primary air/ground frequency.

Report

Used to instruct pilots to advise ATC of specified information; e.g., “Report passing Hamilton VOR.”

Reporting point

A geographical location in relation to which the position of an aircraft is reported.

Request Full Route Clearance

Used by pilots to request that the entire route of flight be read verbatim in an ATC clearance. Such request should be made to preclude receiving an ATC clearance based on the original filed flight plan when a filed IFR flight plan has been revised by the pilot, company, or operations prior to departure.

Restricted area

Airspace designated under 14 CFR part 73 within which the flight of aircraft, while not wholly prohibited, is subject to restriction.

Resume Normal Speed

Used by ATC to advise a pilot that previously issued speed control restrictions are deleted. An instruction to “resume normal speed” does not delete speed restrictions that are applicable to published procedures of upcoming segments of flight, unless specifically stated by ATC. This does not relieve the pilot of those speed restrictions which are applicable to 14 CFR Section 91.117.

Resume Own Navigation

Used by ATC to advise a pilot to resume his/her own navigational responsibility. It is issued after completion of a radar vector or when radar contact is lost while the aircraft is being radar vectored.

Reverse sensing

The VOR needle appearing to indicate the reverse of normal operation.

RF

Radio Frequency.

RFFS

Rescue and Firefighting Services.

Rigidity

The characteristic of a gyroscope that prevents its axis of rotation tilting as the Earth rotates.

Rigidity in space

The principle that a wheel with a heavily weighted rim spinning rapidly will remain in a fixed position in the plane in which it is spinning.

RIL

Runway Intersection Lights

Risk

The future impact of a hazard that is not eliminated or controlled.

Risk management

The part of the decision-making process which relies on situational awareness, problem recognition, and good judgment to reduce risks associated with each flight.

RJ

Regional Jet

RLIM

Runway Light Intensity Monitor

RMI

Radio Magnetic Indicator

RNAV

Area Navigation

Rocket

An aircraft propelled by ejected expanding gases generated in the engine from self-contained propellants and not dependent on the intake of outside substances. It includes any part which becomes separated during the operation.

Roger

I have received all of your last transmission. It should not be used to answer a question requiring a yes or a no answer.

Rotorcraft

A heavier-than-air aircraft that depends principally for its support in flight on the lift generated by one or more rotors.

Roundout (Flare)

A pitch-up during landing approach to reduce rate of descent and forward speed prior to touchdown.

Route

A defined path, consisting of one or more courses in a horizontal plane, which aircraft traverse over the surface of the earth.

Route Segment

As used in Air Traffic Control, a part of a route that can be defined by two navigational fixes, two NAVAIDs, or a fix and a NAVAID.

RR

Low or Medium Frequency Radio Range Station.

RRTES

Reroutes

RSA

Runway Safety Area

RSP

Runway Safety Program

RT

Receiver-Transmitter.

Rudder

The movable primary control surface mounted on the trailing edge of the vertical fin of an airplane. Movement of the rudder rotates the airplane about its vertical axis.

Ruddervator

A pair of control surfaces on the tail of an aircraft arranged in the form of a V. These surfaces, when moved together by the control wheel, serve as elevators, and when moved differentially by the rudder pedals, serve as a rudder.

Runway

A defined rectangular area on a land airport prepared for the landing and takeoff run of aircraft along its length. Runways are normally numbered in relation to their magnetic direction rounded off to the nearest 10 degrees; e.g., Runway 1, Runway 25.

Runway Centerline Lighting

Flush centerline lights spaced at 50-foot intervals beginning 75 feet from the landing threshold and extending to within 75 feet of the opposite end of the runway.

Runway Centerline Lights

Runway centerline lights are installed on some precision approach runways to facilitate landing under adverse visibility conditions. They are located along the runway centerline and are spaced at 50-foot intervals. When viewed from the landing threshold, the runway centerline lights are white until the last 3,000 feet of the runway. The white lights begin to alternate with red for the next 2,000 feet, and for the last 1,000 feet of the runway, all centerline lights are red.

Runway Centerline Markings

The runway centerline identifies the center of the runway and provides alignment guidance during takeoff and landings. The centerline consists of a line of uniformly spaced stripes and gaps.

Runway Edge Lights

Runway edge lights are used to outline the edges of runways during periods of darkness or restricted visibility conditions. These light systems are classified according to the intensity or brightness they are capable of producing: they are the High Intensity Runway Lights (HIRL), Medium Intensity Runway Lights (MIRL), and the Low Intensity Runway Lights (LIRL). The HIRL and MIRL systems have variable intensity controls, whereas the LIRLs normally have one intensity setting.

Runway end identifier lights (REIL)

A pair of synchronized flashing lights, located laterally on each side of the runway threshold, providing rapid and positive identification of the approach end of a runway.

Runway Gradient

The average slope, measured in percent, between two ends or points on a runway. Runway gradient is depicted on Government aerodrome sketches when total runway gradient exceeds 0.3%.

Runway Heading

The magnetic direction that corresponds with the runway centerline extended, not the painted runway numbers on the runway. Pilots cleared to “fly or maintain runway heading” are expected to fly or maintain the published heading that corresponds with the extended centerline of the departure runway (until otherwise instructed by ATC), and are not to apply drift correction; e.g., RWY 4, actual magnetic heading of the runway centerline 044.22°, fly 044°.

Runway Hotspots

Locations on a particular airport that historically have hazardous intersections. Hot spots alert pilots to the fact that there may be a lack of visibility at certain points or the tower may be unable to see that particular intersection. Whatever the reason, pilots need to be aware that these hazardous intersections exist and they should be increasingly vigilant when approaching and taxiing through these intersections. Pilots are typically notified of these areas by a Letter to Airmen or by accessing the FAA Office of Runway Safety.

Runway In Use/Active Runway/Duty Runway

Any runway or runways currently being used for takeoff or landing. When multiple runways are used, they are all considered active runways. In the metering sense, a selectable adapted item which specifies the landing runway configuration or direction of traffic flow. The adapted optimum flight plan from each transition fix to the vertex is determined by the runway configuration for arrival metering processing purposes.

Runway Incursion

Any occurrence at an airport involving an aircraft, vehicle, person, or object on the ground that creates a collision hazard or results in loss of separation with an aircraft taking off, intending to takeoff, landing, or intending to land.

Runway Lights/Runway Edge Lights

Lights having a prescribed angle of emission used to define the lateral limits of a runway. Runway lights are uniformly spaced at intervals of approximately 200 feet, and the intensity may be controlled or preset.

Runway Markings

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.

Runway OFZ

The runway OFZ (Obstacle Free Zone) is a defined volume of airspace centered above the runway. The runway OFZ is the airspace above a surface whose elevation at any point is the same as the elevation of the nearest point on the runway centerline. The runway OFZ extends 200 feet beyond each end of the runway. The width is as follows: 1. For runways serving large airplanes, the greater of: (a) 400 feet, or (b) 180 feet, plus the wingspan of the most demanding airplane, plus 20 feet per 1,000 feet of airport elevation. 2. For runways serving only small airplanes: (a) 300 feet for precision instrument runways. (b) 250 feet for other runways serving small airplanes with approach speeds of 50 knots, or more. (c) 120 feet for other runways serving small airplanes with approach speeds of less than 50 knots.

Runway Overrun

In military aviation exclusively, a stabilized or paved area beyond the end of a runway, of the same width as the runway plus shoulders, centered on the extended runway centerline.

Runway Safety Area

A defined surface surrounding the runway prepared, or suitable, for reducing the risk of damage to airplanes in the event of an undershoot, overshoot, or excursion from the runway. The dimensions of the RSA vary and can be determined by using the criteria contained within AC 150/5300-13, Airport Design, Chapter 3. Figure 3-1 in AC 150/5300-13 depicts the RSA. The design standards dictate that the RSA shall be: a. Cleared, graded, and have no potentially hazardous ruts, humps, depressions, or other surface variations; b. Drained by grading or storm sewers to prevent water accumulation; c. Capable, under dry conditions, of supporting snow removal equipment, aircraft rescue and firefighting equipment, and the occasional passage of aircraft without causing structural damage to the aircraft; and, d. Free of objects, except for objects that need to be located in the runway safety area because of their function. These objects shall be constructed on low impact resistant supports (frangible mounted structures) to the lowest practical height with the frangible point no higher than 3 inches above grade.

Runway Safety Program (RSP)

Designed to create and execute a plan of action that reduces the number of runway incursions at the nations airports.

Runway Threshold Markings

Runway threshold markings come in two configurations. They either consist of eight longitudinal stripes of uniform dimensions disposed symmetrically about the runway centerline, or the number of stripes is related to the runway width. A threshold marking helps identify the beginning of the runway that is available for landing. In some instances, the landing threshold may be displaced.

Runway visibility value (RVV)

The visibility determined for a particular runway by a transmissometer.

Runway Visual Range (RVR)

An instrumentally derived value, based on standard calibrations, that represents the horizontal distance a pilot will see down the runway from the approach end. It is based on the sighting of either high intensity runway lights or on the visual contrast of other targets whichever yields the greater visual range. RVR, in contrast to prevailing or runway visibility, is based on what a pilot in a moving aircraft should see looking down the runway. RVR is horizontal visual range, not slant visual range. It is based on the measurement of a transmissometer made near the touchdown point of the instrument runway and is reported in hundreds of feet. RVR is used in lieu of RVV and/or prevailing visibility in determining minimums for a particular runway.

Runway [ICAO]

A defined rectangular area on a land aerodrome prepared for the landing and take-off of aircraft.

RVR

Runway Visual Range as measured in the Touchdown Zone Area.

RVV

Runway Visibility Value.

RWSL

Runway Status Light

RWY

Runway

RWY CONFIG

Runway Configuration

RY

Runway

SA

Selective Availability.

SAA

Special Activity Airspace

Safety Alert

A safety alert issued by ATC to aircraft under their control if ATC is aware the aircraft is at an altitude which, in the controller’s judgment, places the aircraft in unsafe proximity to terrain, obstructions, or other aircraft. The controller may discontinue the issuance of further alerts if the pilot advises he/she is taking action to correct the situation or has the other aircraft in sight. Note: The issuance of a safety alert is contingent upon the capability of the controller to have an awareness of an unsafe condition. The course of action provided will be predicated on other traffic under ATC control. Once the alert is issued, it is solely the pilot’s prerogative to determine what course of action, if any, he/she will take.

SAM

System Area Monitor

Same Direction Aircraft

Aircraft are operating in the same direction when: a. They are following the same track in the same direction; or b. Their tracks are parallel and the aircraft are flying in the same direction; or c. Their tracks intersect at an angle of less than 45 degrees.

SAMS

Special Use Airspace Management System

SAR

Search and Rescue

SATCOM

Satellite Communications.

Satellite ephemeris data

Data broadcast by the GPS satellite containing very accurate orbital data for that satellite, atmospheric propagation data, and satellite clock error data.

SATNAV

Satellite Navigation

Say Again

Used to request a repeat of the last transmission. Usually specifies transmission or portion thereof not understood or received; e.g., “Say again all after ABRAM VOR.”

Say Altitude

Used by ATC to ascertain an aircraft’s specific altitude/flight level. When the aircraft is climbing or descending, the pilot should state the indicated altitude rounded to the nearest 100 feet.

Say Heading

Used by ATC to request an aircraft heading. The pilot should state the actual heading of the aircraft.

SBAS

Satellite-based Augmentation System

Sea Lane

A designated portion of water outlined by visual surface markers for and intended to be used by aircraft designed to operate on water.

Sea Level

A reference height used to determine standard atmospheric conditions and altitude measurements.

Search And Rescue

A service which seeks missing aircraft and assists those found to be in need of assistance. It is a cooperative effort using the facilities and services of available Federal, state and local agencies. The U.S. Coast Guard is responsible for coordination of search and rescue for the Maritime Region, and the U.S. Air Force is responsible for search and rescue for the Inland Region. Information pertinent to search and rescue should be passed through any air traffic facility or be transmitted directly to the Rescue Coordination Center by telephone.

Search And Rescue Facility

A facility responsible for maintaining and operating a search and rescue (SAR) service to render aid to persons and property in distress. It is any SAR unit, station, NET, or other operational activity which can be usefully employed during an SAR Mission; e.g., a Civil Air Patrol Wing, or a Coast Guard Station.

SECNOT

Security Notice

Sectional aeronautical charts

Designed for visual navigation of slow- or medium-speed aircraft. Topographic information on these charts features the portrayal of relief, and a judicious selection of visual check points for VFR flight. Aeronautical information includes visual and radio aids to navigation, airports, controlled airspace, restricted areas, obstructions and related data.

See And Avoid

When weather conditions permit, pilots operating IFR or VFR are required to observe and maneuver to avoid other aircraft. Right-of-way rules are contained in 14 CFR Part 91.

Segmented Circle

A visual ground based structure to provide traffic pattern information.

Segments Of An Instrument Approach Procedure

An instrument approach procedure may have as many as four separate segments depending on how the approach procedure is structured. Initial Approach, Intermediate Approach, Final Approach, and Missed Approach.

Selective availability (SA)

A satellite technology permitting the Department of Defense (DOD) to create, in the interest of national security, a significant clock and ephemeris error in the satellites, resulting in a navigation error.

Sensitive altimeter

A form of multipointer pneumatic altimeter with an adjustable barometric scale that allows the reference pressure to be set to any desired level.

Service

A generic term that designates functions or assistance available from or rendered by air traffic control. For example, Class C service would denote the ATC services provided within a Class C airspace area.

Service ceiling

The maximum density altitude where the best rate-of-climb airspeed will produce a 100-feet-per-minute climb at maximum weight while in a clean configuration with maximum continuous power.

Severe Icing

The rate of accumulation is such that deicing/anti-icing equipment fails to reduce or control the hazard. Immediate flight diversion is necessary.

SFL

Sequenced Flashing Lights

SFR

Special Flight Rules

Short Takeoff And Landing Aircraft

An aircraft which, at some weight within its approved operating weight, is capable of operating from a runway in compliance with the applicable STOL characteristics, airworthiness, operations, noise, and pollution standards.

Show

Unless the context otherwise requires, to show to the satisfaction of the Administrator.

Sideslip

A slip in which the airplane’s longitudinal axis remains parallel to the original flightpath, but the airplane no longer flies straight ahead. Instead, the horizontal component of wing lift forces the airplane to move sideways toward the low wing.

SIGMET

A weather advisory issued concerning weather significant to the safety of all aircraft. SIGMET advisories cover severe and extreme turbulence, severe icing, and widespread dust or sandstorms that reduce visibility to less than 3 miles.

Simplex

Transmission and reception on the same frequency.

Single-Pilot Resource Management (SRM)

The art/science of managing all the resources (both onboard the aircraft and from outside sources) available to a single pilot (prior and during flight) to ensure that the successful outcome of the flight is never in doubt.

Situational awareness

Pilot knowledge of where the aircraft is in regard to location, air traffic control, weather, regulations, aircraft status, and other factors that may affect flight.

Skid

A condition where the tail of the airplane follows a path outside the path of the nose during a turn.

Skidding turn

An uncoordinated turn in which the rate of turn is too great for the angle of bank, pulling the aircraft to the outside of the turn.

Slant range

The horizontal distance from the aircraft antenna to the ground station, due to line-of-sight transmission of the DME signal.

Slaved compass

A system whereby the heading gyro is “slaved to,” or continuously corrected to bring its direction readings into agreement with a remotely located magnetic direction sensing device (usually a flux valve or flux gate compass).

Slip

An intentional maneuver to decrease airspeed or increase rate of descent, and to compensate for a crosswind on landing. A slip can also be unintentional when the pilot fails to maintain the aircraft in coordinated flight.

Slipping turn

An uncoordinated turn in which the aircraft is banked too much for the rate of turn, so the horizontal lift component is greater than the centrifugal force, pulling the aircraft toward the inside of the turn.

Slow Taxi

To taxi a float plane at low power or low RPM.

SM

Statute Mile

Small

An Aircraft Class Wake Turbulence Separation Minima. Aircraft of 41,000 pounds or less maximum certificated takeoff weight.

Small Aircraft

An aircraft weighing 12,500 pounds or less, maximum certificated takeoff weight. As defined in 14 CFR part 1.

SNR

Signal-to-noise Ratio

SOP

Standard Operating Procedure

Speak Slower

Used in verbal communications as a request to reduce speech rate.

Special Activity Airspace (SAA)

Any airspace with defined dimensions within the National Airspace System wherein limitations may be imposed upon aircraft operations. This airspace may be restricted areas, prohibited areas, military operations areas, air ATC assigned airspace, and any other designated airspace areas. The dimensions of this airspace are programmed into URET and can be designated as either active or inactive by screen entry. Aircraft trajectories are constantly tested against the dimensions of active areas and alerts issued to the applicable sectors when violations are predicted.

Special Emergency

A condition of air piracy or other hostile act by a person(s) aboard an aircraft which threatens the safety of the aircraft or its passengers.

Special flight permit

A flight permit issued to an aircraft that does not meet airworthiness requirements but is capable of safe flight. A special flight permit can be issued to move an aircraft for the purposes of maintenance or repair, buyer delivery, manufacturer flight tests, evacuation from danger, or customer demonstration. Also referred to as a ferry permit.

Special Use Airspace

Airspace of defined dimensions identified by an area on the surface of the earth wherein activities must be confined because of their nature and/or wherein limitations may be imposed upon aircraft operations that are not a part of those activities. Types of special use airspace are: Alert Area, Controlled Firing Area, Military Operations Area (MOA), Prohibited Area, Restricted Area, and Warning Area.

Special VFR Conditions

Meteorological conditions that are less than those required for basic VFR flight in Class B, C, D, or E surface areas and in which some aircraft are permitted flight under visual flight rules.

Special VFR Operations

Aircraft operating in accordance with clearances within Class B, C, D, and E surface areas in weather conditions less than the basic VFR weather minima. Such operations must be requested by the pilot and approved by ATC.

Speed

The distance traveled in a given time.

Spin

An aggravated stall that results in what is termed an “autorotation” wherein the airplane follows a downward corkscrew path. As the airplane rotates around the vertical axis, the rising wing is less stalled than the descending wing creating a rolling, yawing, and pitching motion.

Spiral instability

A condition that exists when the static directional stability of the airplane is very strong as compared to the effect of its dihedral in maintaining lateral equilibrium.

Spiraling slipstream

The slipstream of a propeller-driven airplane rotates around the airplane. This slipstream strikes the left side of the vertical fin, causing the aircraft to yaw slightly. Rudder offset is sometimes used by aircraft designers to counteract this tendency.

SPS

Standard Positioning Service

SPT

Strategic Planning Team. The Strategic Planning Team acts as a focal point for the development of collaborative Strategic Plans of Operation. Their goal is to provide advanced planning information for system users and air traffic facilities in order to maximize the utilization of the NAS in an organized and equitable manner.

Squawk (Mode, Code, Function)

Activate specific modes/codes/functions on the aircraft transponder; e.g., “Squawk three/alpha, two one zero five, low.”

SRM

Single-pilot Resource Management.

SSR

Secondary Surveillance Radar.

SSV

Standard Service Volume.

Stabilator

A single-piece horizontal tail surface on an airplane that pivots around a central hinge point. A stabilator serves the purposes of both the horizontal stabilizer and the elevators.

Stability

The inherent quality of an airplane to correct for conditions that may disturb its equilibrium, and to return or to continue on the original flightpath. It is primarily an airplane design characteristic.

Stabilized Approach

A landing approach in which the pilot establishes and maintains a constant angle glidepath towards a predetermined point on the landing runway. It is based on the pilot’s judgment of certain visual cues, and depends on the maintenance of a constant final descent airspeed and configuration.

Stall

A rapid decrease in lift caused by the separation of airflow from the wing’s surface brought on by exceeding the critical angle of attack. A stall can occur at any pitch attitude or airspeed.

Stand By

Means the controller or pilot must pause for a few seconds, usually to attend to other duties of a higher priority. Also means to wait as in “stand by for clearance.” The caller should reestablish contact if a delay is lengthy. “Stand by” is not an approval or denial.

Standard Atmosphere

At sea level, the standard atmosphere consists of a barometric pressure of 29.92 inches of mercury (in. Hg.) or 1013.2 millibars, and a temperature of 15°C (59°F). Pressure and temperature normally decrease as altitude increases. The standard lapse rate in the lower atmosphere for each 1,000 feet of altitude is approximately 1 in. Hg. and 2°C (3.5°F). For example, the standard pressure and temperature at 3,000 feet mean sea level (MSL) is 26.92 in. Hg. 29.92" Hg – 3" Hg) and 9°C (15°C - 6°C).

Standard Day

See Standard Atmosphere.

Standard Instrument Approach Procedure (SIAP)

Instrument Approach Procedure.

Standard rate turn

A turn in which an aircraft changes its direction at a rate of 3° per second (360° in 2 minutes) for low- or medium-speed aircraft. For high-speed aircraft, the standard rate turn is 1 1⁄2° per second (360° in 4 minutes).

Standard T

An RNAV approach whose design allows direct flight to any one of three initial approach fixes (IAF) and eliminates the need for procedure turns. The standard design is to align the procedure on the extended centerline with the missed approach point (MAP) at the runway threshold, the final approach fix (FAF), and the initial approach/intermediate fix (IAF/IF). The other two IAFs will be established perpendicular to the IF.

Standard Terminal Arrival (STAR) Charts

Designed to expedite air traffic control arrival procedures and to facilitate transition between en route and instrument approach operations. Each STAR procedure is presented as a separate chart and may serve a single airport or more than one airport in a given geographical location. i. Airport Taxi Charts Designed to expedite the efficient and safe flow of ground traffic at an airport. These charts are identified by the official airport name; e.g., Ronald Reagan Washington National Airport.

Standard-Rate Turn

A turn at the rate of 3º per second which enables the airplane to complete a 360º turn in 2 minutes.

Static longitudinal stability

The aerodynamic pitching moments required to return the aircraft to the equilibrium angle of attack.

Static pressure

Pressure of air that is still or not moving, measured perpendicular to the surface of the aircraft.

Static stability

The initial tendency an aircraft displays when disturbed from a state of equilibrium.

Station

A location in the airplane that is identified by a number designating its distance in inches from the datum. The datum is, therefore, identified as station zero. An item located at station +50 would have an arm of 50 inches.

STC

Supplemental Type Certificate

Steep turns

In instrument flight, any turn greater than standard rate; in visual flight, anything greater than a 45° bank.

STMP

Special Traffic Management Program. Reservation program implemented to regulate arrivals and/or departures at airports that are in areas hosting special events such as the Masters Golf Tournament and Indianapolis 500.

STOL Aircraft

Short Takeoff And Landing Aircraft.

Stop Altitude Squawk

Used by ATC to inform an aircraft to turn-off the automatic altitude reporting feature of its transponder. It is issued when the verbally reported altitude varies 300 feet or more from the automatic altitude report.

Stop And Go

A procedure wherein an aircraft will land, make a complete stop on the runway, and then commence a takeoff from that point.

Stop Squawk (Mode Or Code)

Used by ATC to tell the pilot to turn specified functions of the aircraft transponder off.

Stopway

An area beyond the takeoff runway no less wide than the runway and centered upon the extended centerline of the runway, able to support the airplane during an aborted takeoff, without causing structural damage to the airplane, and designated by the airport authorities for use in decelerating the airplane during an aborted takeoff.

Straight-In Approach VFR

Entry into the traffic pattern by interception of the extended runway centerline (final approach course) without executing any other portion of the traffic pattern.

SUA

Special Use Airspace

Sunset And Sunrise

The mean solar times of sunset and sunrise as published in the Nautical Almanac, converted to local standard time for the locality concerned. Within Alaska, the end of evening civil twilight and the beginning of morning civil twilight, as defined for each locality.

Surface Area

The airspace contained by the lateral boundary of the Class B, C, D, or E airspace designated for an airport that begins at the surface and extends upward.

SVFR

Special Visual Flight Rules

SWAP

Severe Weather Avoidance Plan. An approved plan to minimize the effect of severe weather on traffic flows in impacted terminal and/or ARTCC areas. SWAP is normally implemented to provide the least disruption to the ATC system when flight through portions of airspace is difficult or impossible due to severe weather.

Synthetic vision

A computer-generated image of the external scene topography from the perspective of the flight deck that is derived from aircraft attitude, high-precision navigation solution, and database of terrain, obstacles and relevant cultural features.

Synthetic vision system

An electronic means to display a synthetic vision image of the external scene topography to the flight crew.

TA

Traffic Advisory

TAC

Terminal Area Chart

TACAN

Tactical Air Navigation Aid. An ultra-high frequency electronic rho-theta air navigation aid which provides suitably equipped aircraft with a continuous indication of bearing and distance to the TACAN station.

TAF

Terminal Aerodrome Forecast

Tailwind

Any wind more than 90 degrees to the longitudinal axis of the runway. The magnetic direction of the runway shall be used as the basis for determining the longitudinal axis.

Takeoff Area

Landing Area.

Takeoff distance

The distance required to complete an all-engines operative takeoff to the 35-foot height. It must be at least 15 percent less than the distance required for a one-engine inoperative engine takeoff. This distance is not normally a limiting factor as it is usually less than the one-engine inoperative takeoff distance.

Takeoff power

(1) With respect to reciprocating engines, the brake horsepower that is developed under standard sea level conditions, and under the maximum conditions of crankshaft rotational speed and engine manifold pressure approved for the normal takeoff, and limited in continuous use to the period of time shown in the approved engine specification; and
(2) With respect to turbine engines, the brake horsepower that is developed under static conditions at a specified altitude and atmospheric temperature, and under the maximum conditions of rotor shaft rotational speed and gas temperature approved for the normal takeoff, and limited in continuous use to the period of time shown in the approved engine specification.

Takeoff Roll (Ground Roll)

The total distance required for an aircraft to become airborne.

Target

The indication shown on an analog display resulting from a primary radar return or a radar beacon reply.

Tarmac Delay

The holding of an aircraft on the ground either before departure or after landing with no opportunity for its passengers to deplane.

TAS

True Airspeed.

TAWS

Terrain Awareness and Warning System.

Taxi

The movement of an airplane under its own power on the surface of an airport (14 CFR Section 135.100 [Note]). Also, it describes the surface movement of helicopters equipped with wheels.

Taxi Patterns

Patterns established to illustrate the desired flow of ground traffic for the different runways or airport areas available for use.

Taxiway Lights

Omnidirectional lights that outline the edges of the taxiway and are blue in color.

Taxiway Turnoff Lights

Flush lights which emit a steady green color.

TCAS

A Traffic Alert and Collision Avoidance System.

TD

Time Difference

TDLS

Tower Data Link System

TDWR

Terminal Doppler Weather Radar

TDZL

Touchdown Zone Lights

Temporary flight restriction (TFR)

Restriction to flight imposed in order to:
1. Protect persons and property in the air or on the surface from an existing or imminent flight associated hazard;
2. Provide a safe environment for the operation of disaster relief aircraft;
3. Prevent an unsafe congestion of sightseeing aircraft above an incident;
4. Protect the President, Vice President, or other public figures; and,
5. Provide a safe environment for space agency operations.
Pilots are expected to check appropriate NOTAMs during flight planning when conducting flight in an area where a temporary flight restriction is in effect.

Terminal Area

A general term used to describe airspace in which approach control service or airport traffic control service is provided.

Terminal Radar Service Area

Airspace surrounding designated airports wherein ATC provides radar vectoring, sequencing, and separation on a full-time basis for all IFR and participating VFR aircraft. The AIM contains an explanation of TRSA. TRSAs are depicted on VFR aeronautical charts. Pilot participation is urged but is not mandatory.

Terminal VFR Radar Service

A national program instituted to extend the terminal radar services provided instrument flight rules (IFR) aircraft to visual flight rules (VFR) aircraft. The program is divided into four types service referred to as basic radar service, terminal radar service area (TRSA) service, Class B service and Class C service. The type of service provided at a particular location is contained in the Airport/Facility Directory.

Terrain awareness and warning system (TAWS)

A timed-based system that provides information concerning potential hazards with fixed objects by using GPS positioning and a database of terrain and obstructions to provide true predictability of the upcoming terrain and obstacles.

Terrain/Obstruction Alert

Tetrahedron

A large, triangular-shaped, kite-like object installed near the runway. Tetrahedrons are mounted on a pivot and are free to swing with the wind to show the pilot the direction of the wind as an aid in takeoffs and landings.

TFC

Traffic

TFR

Temporary Flight Restriction.

That Is Correct

The understanding you have is right.

THL

Takeoff Hold Lights

Three-Hour Tarmac Rule

Rule that relates to Department of Transportation (DOT) requirements placed on airlines when tarmac delays are anticipated to reach 3 hours.

Threshold

The beginning of that portion of the runway usable for landing.

Threshold Lights

Fixed green lights arranged symmetrically left and right of the runway centerline, identifying the runway threshold.

Thrust (aerodynamic force)

The forward aerodynamic force produced by a propeller, fan, or turbojet engine as it forces a mass of air to the rear, behind the aircraft.

Thrust line

An imaginary line passing through the center of the propeller hub, perpendicular to the plane of the propeller rotation.

TIBS

Telephone Information Briefing Service - Discontinued in the CONUS in September 2018 and in Alaska on Jan 1, 2020.

Timed turn

A turn in which the clock and the turn coordinator are used to change heading a definite number of degrees in a given time.

TIS

Traffic Information Service

Torque

1. A resistance to turning or twisting.
2. Forces that produce a twisting or rotating motion.
3. In an airplane, the tendency of the aircraft to turn (roll) in the opposite direction of rotation of the engine and propeller.

Total Drag

The sum of the parasite and induced drag.

Touch-And-Go

An operation by an aircraft that lands and departs on a runway without stopping or exiting the runway.

Touch-And-Go Landing

Touch-And-Go.

Touchdown

A. The point at which an aircraft first makes contact with the landing surface.
B. Concerning a precision radar approach (PAR), it is the point where the glide path intercepts the landing surface.

Touchdown Zone Lighting

Two rows of transverse light bars located symmetrically about the runway centerline normally at 100 foot intervals. The basic system extends 3,000 feet along the runway.

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).

Trace Icing

Ice becomes perceptible. Rate of accumulation is slightly greater than the rate of sublimation. Deicing/anti-icing equipment is not utilized unless encountered for an extended period of time (over 1 hour).

Track

The actual path made over the ground in flight.

Tracking

Flying a heading that will maintain the desired track to or from the station regardless of crosswind conditions.

TRACON

Terminal Radar Control Facility. A terminal ATC facility that uses radar and nonradar capabilities to provide approach control services to aircraft arriving, departing, or transiting airspace controlled by the facility.

Traffic

A. A term used by a controller to transfer radar identification of an aircraft to another controller for the purpose of coordinating separation action. Traffic is normally issued:
1. In response to a handoff or point out,
2. In anticipation of a handoff or point out, or
3. In conjunction with a request for control of an aircraft.
B. A term used by ATC to refer to one or more aircraft.

Traffic Advisories

Advisories issued to alert pilots to other known or observed air traffic which may be in such proximity to the position or intended route of flight of their aircraft to warrant their attention. Such advisories may be based on: a. Visual observation. b. Observation of radar identified and nonidentified aircraft targets on an ATC radar display, or c. Verbal reports from pilots or other facilities. Note 1: The word “traffic” followed by additional information, if known, is used to provide such advisories; e.g., “Traffic, 2 o’clock, one zero miles, southbound, eight thousand.” Note 2: Traffic advisory service will be provided to the extent possible depending on higher priority duties of the controller or other limitations; e.g., radar limitations, volume of traffic, frequency congestion, or controller workload. Radar/ nonradar traffic advisories do not relieve the pilot of his/her responsibility to see and avoid other aircraft. Pilots are cautioned that there are many times when the controller is not able to give traffic advisories concerning all traffic in the aircraft’s proximity; in other words, when a pilot requests or is receiving traffic advisories, he/she should not assume that all traffic will be issued.

Traffic Alert

(aircraft call sign), TURN (left/right) IMMEDIATELY, (climb/descend) AND MAINTAIN (altitude).

Traffic In Sight

Used by pilots to inform a controller that previously issued traffic is in sight.

Traffic Information

Traffic Advisories.

Traffic information service (TIS)

A ground-based service providing information to the flight deck via data link using the S-mode transponder and altitude encoder to improve the safety and efficiency of “see and avoid” flight through an automatic display that informs the pilot of nearby traffic.

Traffic No Factor

Indicates that the traffic described in a previously issued traffic advisory is no factor.

Traffic No Longer Observed

Indicates that the traffic described in a previously issued traffic advisory is no longer depicted on radar, but may still be a factor.

Traffic Pattern

The traffic flow that is prescribed for aircraft landing at, taxiing on, or taking off from an airport. The components of a typical traffic pattern are upwind leg, crosswind leg, downwind leg, base leg, and final approach.

Trailing edge

The portion of the airfoil where the airflow over the upper surface rejoins the lower surface airflow.

Transfer Of Control

That action whereby the responsibility for the separation of an aircraft is transferred from one controller to another.

Transition

The general term that describes the change from one phase of flight or flight condition to another; e.g., transition from en route flight to the approach or transition from instrument flight to visual flight.

Transition training

An instructional program designed to familiarize and qualify a pilot to fly types of aircraft not previously flown, such as tail wheel aircraft, high performance aircraft, and aircraft capable of flying at high altitudes.

Transmitting In The Blind

Transponder

The airborne radar beacon receiver/transmitter portion of the Air Traffic Control Radar Beacon System (ATCRBS) which automatically receives radio signals from interrogators on the ground, and selectively replies with a specific reply pulse or pulse group only to those interrogations being received on the mode to which it is set to respond.

Transponder code

One of 4,096 four-digit discrete codes ATC assigns to distinguish between aircraft.

Transponder Observed

Phraseology used to inform a VFR pilot the aircraft’s assigned beacon code and position have been observed. Specifically, this term conveys to a VFR pilot the transponder reply has been observed and its position correlated for transit through the designated area.

Trend

Immediate indication of the direction of aircraft movement, as shown on instruments.

Tricycle gear

Landing gear employing a third wheel located on the nose of the aircraft.

Trim

To adjust the aerodynamic forces on the control surfaces so that the aircraft maintains the set attitude without any control input.

Trim tab

A small auxiliary hinged portion of a movable control surface that can be adjusted during flight to a position resulting in a balance of control forces.

TRSA

Terminal Radar Service Area

TRSA Service

This service provides, in addition to basic radar service, sequencing of all IFR and participating VFR aircraft to the primary airport and separation between all participating VFR aircraft. The purpose of this service is to provide separation between all participating VFR aircraft and all IFR aircraft operating within the area defined as a TRSA.

True airspeed

Actual airspeed, determined by applying a correction for pressure altitude and temperature to the CAS.

True Altitude

The vertical distance of the airplane above sea level—the actual altitude. It is often expressed as feet above mean sea level (MSL). Airport, terrain, and obstacle elevations on aeronautical charts are true altitudes.

True Course

A predetermined desired course direction to be followed (measured in degrees from true north).

TSA

Transportation Security Administration (TSA) protects the nation’s transportation systems to ensure freedom of movement for people and commerce.

TSD

Traffic Situation Display. A tool used by Traffic Management Specialists to monitor the position of air traffic and to determine the traffic demand on airports and sectors.

TSO

Technical Standard Order.

TSTMS

Thunderstorms

Turbojet Aircraft

An aircraft having a jet engine in which the energy of the jet operates a turbine which in turn operates the air compressor.

Turboprop Aircraft

An aircraft having a jet engine in which the energy of the jet operates a turbine which drives the propeller.

Turn Anticipation

(maneuver anticipation).

Turn coordinator

A rate gyro that senses both roll and yaw due to the gimbal being canted. Has largely replaced the turn-and-slip indicator in modern aircraft.

Turn-and-slip indicator

A flight instrument consisting of a rate gyro to indicate the rate of yaw and a curved glass inclinometer to indicate the relationship between gravity and centrifugal force. The turn-and-slip indicator indicates the relationship between angle of bank and rate of yaw. Also called a turn-and-bank indicator.

Turning Error

One of the errors inherent in a magnetic compass caused by the dip compensating weight. It shows up only on turns to or from northerly headings in the Northern Hemisphere and southerly headings in the Southern Hemisphere. Turning error causes the compass to lead turns to the north or south and lag turns away from the north or south.

TVOR

Very High Frequency Terminal Omnirange Station.

TWEB

Transcribed Weather Broadcast - Discontinued in the CONUS in September 2018 and in Alaska on Jan 1, 2020.

TWIB

Terminal Weather Information for Pilots System

Two-Way Radio Communications Failure

Lost Communications.

Type

(1) As used with respect to the certification, ratings, privileges, and limitations of airmen, a specific make and basic model of aircraft, including modifications thereto that do not change its handling or flight characteristics. Examples include: DC–7, 1049, and F–27; and
(2) As used with respect to the certification of aircraft, those aircraft which are similar in design. Examples include: DC–7 and DC–7C; 1049G and 1049H; and F–27 and F–27F.
(3) As used with respect to the certification of aircraft engines, those engines which are similar in design. For example, JT8D and JT8D–7 are engines of the same type, and JT9D–3A and JT9D–7 are engines of the same type.

U.S.

United States

UA

Unmanned Aircraft

UAS

Unmanned Aircraft System

UAV

Unmanned Aerial Vehicle

UFO

Unidentified Flying Object

UHF

Ultrahigh Frequency

The frequency band between 300 and 3,000 MHz. The bank of radio frequencies used for military air/ground voice communications. In some instances this may go as low as 225 MHz and still be referred to as UHF.

Ultralight Vehicle

An aeronautical vehicle operated for sport or recreational purposes which does not require FAA registration, an airworthiness certificate, nor pilot certification. They are primarily single occupant vehicles, although some two-place vehicles are authorized for training purposes. Operation of an ultralight vehicle in certain airspace requires authorization from ATC.

Unable

Indicates inability to comply with a specific instruction, request, or clearance.

Uncaging

Unlocking the gimbals of a gyroscopic instrument, making it susceptible to damage by abrupt flight maneuvers or rough handling.

Uncontrolled airspace

Class G airspace that has not been designated as Class A, B, C, D, or E. It is airspace in which air traffic control has no authority or responsibility to control air traffic; however, pilots should remember there are VFR minimums which apply to this airspace.

Under The Hood

Indicates that the pilot is using a hood to restrict visibility outside the cockpit while simulating instrument flight. An appropriately rated pilot is required in the other control seat while this operation is being conducted.

Underpower

Using less power than required for the purpose of achieving a faster rate of airspeed change.

Unicom

A nongovernment communication facility which may provide airport information at certain airports. Locations and frequencies of UNICOMs are shown on aeronautical charts and publications.

United States

In a geographical sense means (1) the States, the District of Columbia, Puerto Rico, and the possessions, including the territorial waters, and (2) the airspace of those areas.

Unpublished Route

A route for which no minimum altitude is published or charted for pilot use. It may include a direct route between NAVAIDs, a radial, a radar vector, or a final approach course beyond the segments of an instrument approach procedure.

Unreliable (GPS/WAAS)

An advisory to pilots indicating the expected level of service of the GPS and/or WAAS may not be available. Pilots must then determine the adequacy of the signal for desired use.

Unusual attitude

An unintentional, unanticipated, or extreme aircraft attitude.

Upwind Leg

A flight path parallel to the landing runway in the direction of landing.

Urgency

A condition of being concerned about safety and of requiring timely but not immediate assistance; a potential distress condition.

Useful load

The weight of the pilot, copilot, passengers, baggage, usable fuel, and drainable oil. It is the basic empty weight subtracted from the maximum allowable gross weight. This term applies to general aviation aircraft only.

User-defined waypoints

Waypoint location and other data which may be input by the user, this is the only GPS database information that may be altered (edited) by the user.

UTC

Coordinated Universal Time (abbreviated as UTC, and therefore often spelled out as Universal Time Coordinated and sometimes as Universal Coordinated Time) is the standard time common to every place in the world. Formerly and still widely called Greenwich Mean Time (GMT) and also World Time, UTC nominally reflects the mean solar time along the Earth´s prime meridian.

Utility Category

A category of aircraft certificated under 14 CFR part 23 and CAR part 3 that permits limited acrobatic maneuvers but restricts the weight and the CG range.

UWS

Urgent Weather SIGMET

Va

Design maneuvering speed.

VAPS

Visual Approaches. An approach conducted under Instrument Flight Rules that authorizes the pilot to proceed visually and clear of clouds to the airport. Usually this will be used in conjunction with Visual Separation. When using Visual Separation, a pilot sees the other aircraft involved, and upon instructions from the controller, provides his own separation by maneuvering his aircraft as necessary to avoid it. Visual Separation requires less spacing between aircraft than radar separation allowing more aircraft to land in a given period of time.

Variation

Compass error caused by the difference in the physical locations of the magnetic north pole and the geographic north pole.

VASI

Visual Approach Slope Indicator

Vb

Design speed for maximum gust intensity.

Vc

Design cruising speed.

VCOA

Visual Climb Over the Airport

Vd

Design diving speed.

VDA

Vertical Descent Angle

Vdf / Mdf

Demonstrated flight diving speed.

Vector

A force vector is a graphic representation of a force and shows both the magnitude and direction of the force.

Vectoring

Navigational guidance by assigning headings.

Velocity

The speed or rate of movement in a certain direction.

Venturi tube

A specially shaped tube attached to the outside of an aircraft to produce suction to allow proper operation of gyro instruments.

Verify

Request confirmation of information; e.g., “verify assigned altitude.”

Verify Specific Direction Of Takeoff (Or Turns After Takeoff)

Used by ATC to ascertain an aircraft’s direction of takeoff and/or direction of turn after takeoff. It is normally used for IFR departures from an airport not having a control tower. When direct communication with the pilot is not possible, the request and information may be relayed through an FSS, dispatcher, or by other means.

Vertical axis

An imaginary line passing vertically through the center of gravity of an aircraft. The vertical axis is called the z-axis or the yaw axis.

Vertical card compass

A magnetic compass that consists of an azimuth on a vertical card, resembling a heading indicator with a fixed miniature airplane to accurately present the heading of the aircraft. The design uses eddy current damping to minimize lead and lag during turns.

Vertical speed indicator (VSI)

A rate-of-pressure change instrument that gives an indication of any deviation from a constant pressure level.

Vertical stability

Stability about an aircraft’s vertical axis. Also called yawing or directional stability.

Vertical Takeoff And Landing Aircraft

Aircraft capable of vertical climbs and/or descents and of using very short runways or small areas for takeoff and landings. These aircraft include, but are not limited to, helicopters.

Very High Frequency

The frequency band between 30 and 300 MHz. Portions of this band, 108 to 118 MHz, are used for certain NAVAIDs; 118 to 136 MHz are used for civil air/ground voice communications. Other frequencies in this band are used for purposes not related to air traffic control.

Very Low Frequency

The frequency band between 3 and 30 kHz.

Very-high frequency (VHF)

A band of radio frequencies falling between 30 and 300 MHz.

Very-high frequency omnidirectional range (VOR)

Electronic navigation equipment in which the flight deck instrument identifies the radial or line from the VOR station, measured in degrees clockwise from magnetic north, along which the aircraft is located.

Vf

Design flap speed.

Vfc / Mfc

Maximum Speed For Stability Characteristics.

VFR

Visual Flight Rules. Rules that govern the procedures for conducting flight under visual conditions. The term "VFR" is also used in the United States to indicate weather conditions that are equal to or greater than minimum VFR requirements. In addition, it is used by pilots and controllers to indicate type of flight plan.

VFR Aircraft

An aircraft conducting flight in accordance with visual flight rules.

VFR Conditions

Weather conditions equal to or better than the minimum for flight under visual flight rules. The term may be used as an ATC clearance/instruction only when: a. An IFR aircraft requests a climb/descent in VFR conditions. b. The clearance will result in noise abatement benefits where part of the IFR departure route does not conform to an FAA approved noise abatement route or altitude. c. A pilot has requested a practice instrument approach and is not on an IFR flight plan. Note: All pilots receiving this authorization must comply with the VFR visibility and distance from cloud criteria in 14 CFR Part 91. Use of the term does not relieve controllers of their responsibility to separate aircraft in Class B and Class C airspace or TRSAs as required by FAAO JO 7110.65. When used as an ATC clearance/instruction, the term may be abbreviated “VFR;” e.g., “MAINTAIN VFR,” “CLIMB/DESCEND VFR,” etc.

VFR Flight

VFR Aircraft.

VFR Military Training Routes

Routes used by the Department of Defense and associated Reserve and Air Guard units for the purpose of conducting low-altitude navigation and tactical training under VFR below 10,000 feet MSL at airspeeds in excess of 250 knots IAS.

VFR Not Recommended

An advisory provided by a flight service station to a pilot during a preflight or inflight weather briefing that flight under visual flight rules is not recommended. To be given when the current and/or forecast weather conditions are at or below VFR minimums. It does not abrogate the pilot’s authority to make his/her own decision.

VFR over the top

A VFR operation in which an aircraft operates in VFR conditions on top of an undercast.

VFR terminal area chart

At a scale of 1:250,000, a chart that depicts Class B airspace, which provides for the control or segregation of all the aircraft within the Class B airspace. The chart depicts topographic information and aeronautical information including visual and radio aids to navigation, airports, controlled airspace, restricted areas, obstructions, and related data.

VGSI

Visual Glide Slope Indicator

Vh

Maximum speed in level flight with maximum continuous power.

VHF

Very High Frequency.

VHF Omnidirectional Range/Tactical Air Navigation

VORTAC.

Victor airways

Airways based on a centerline that extends from one VOR or VORTAC 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.

VIP

Video Integrator Processor

Visibility

The ability, as determined by atmospheric conditions and expressed in units of distance, to see and identify prominent unlighted objects by day and prominent lighted objects by night. Visibility is reported as statute miles, hundreds of feet or meters.

Visual Approach

An approach conducted on an instrument flight rules (IFR) flight plan which authorizes the pilot to proceed visually and clear of clouds to the airport. The pilot must, at all times, have either the airport or the preceding aircraft in sight. This approach must be authorized and under the control of the appropriate air traffic control facility. Reported weather at the airport must be ceiling at or above 1,000 feet and visibility of 3 miles or greater.

Visual Approach Slope Indicator (VASI)

The most common visual glidepath system in use. The VASI provides obstruction clearance within 10° of the extended runway centerline, and to 4 nautical miles (NM) from the runway threshold.

Visual flight rules (VFR)

Flight rules adopted by the FAA governing aircraft flight using visual references. VFR operations specify the amount of ceiling and the visibility the pilot must have in order to operate according to these rules. When the weather conditions are such that the pilot can not operate according to VFR, he or she must use instrument flight rules (IFR).

Visual Holding

The holding of aircraft at selected, prominent geographical fixes which can be easily recognized from the air.

Visual meteorological conditions (VMC)

Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling meeting or exceeding the minimums specified for VFR.

Visual Segment

Published Instrument Approach Procedure Visual Segment.

Visual Separation

A means employed by ATC to separate aircraft in terminal areas and en route airspace in the NAS. There are two ways to effect this separation: a. The tower controller sees the aircraft involved and issues instructions, as necessary, to ensure that the aircraft avoid each other. b. A pilot sees the other aircraft involved and upon instructions from the controller provides his/her own separation by maneuvering his/her aircraft as necessary to avoid it. This may involve following another aircraft or keeping it in sight until it is no longer a factor.

Vle

Maximum landing gear extended speed.

VLF

Very Low Frequency

VLJ

Very Light Jet

Vlo

Maximum landing gear operating speed.

Vlof

Lift-off speed.

Vmc

Minimum control speed with the critical engine inoperative.

VMC

Visual Meteorological Conditions

Vmini

Instrument flight minimum speed, utilized in complying with minimum limit speed requirements for instrument flight

Vmo/ Mmo

Maximum operating limit speed.

Vne

The never-exceed speed. Operating above this speed is prohibited since it may result in damage or structural failure. The red line on the airspeed indicator.

Vno

Maximum structural cruising speed.

VOL

Volume. Usually used to indicate that the volume of aircraft exceeds the airport´s capacity.

VOR

Very High Frequency Omni Directional Range. A ground-based electronic navigation aid transmitting very high frequency navigation signals, 360 degrees in azimuth, oriented from magnetic north. Used as the basis for navigation in the National Airspace System. The VOR periodically identifies itself by Morse Code and may have an additional voice identification feature. Voice features may be used by ATC or FSS for transmitting instructions/information to pilots.

VOR test facility (VOT)

A ground facility which emits a test signal to check VOR receiver accuracy. Some VOTs are available to the user while airborne, while others are limited to ground use only.

VORTAC

A navigation aid providing VOR azimuth, TACAN azimuth, and TACAN distance measuring equipment (DME) at one site.

Vortices

Circular patterns of air created by the movement of an airfoil through the air when generating lift. As an airfoil moves through the atmosphere in sustained flight, an area of area of low pressure is created above it. The air flowing from the high pressure area to the low pressure area around and about the tips of the airfoil tends to roll up into two rapidly rotating vortices, cylindrical in shape. These vortices are the most predominant parts of aircraft wake turbulence and their rotational force is dependent upon the wing loading, gross weight, and speed of the generating aircraft. The vortices from medium to heavy aircraft can be of extremely high velocity and hazardous to smaller aircraft.

VOT

VOR Test Facility

Vr

Rotation speed.

VR

VFR Military Training Route

Vref

The reference landing approach speed, usually about 1.3 times Vso plus 50 percent of the wind gust speed in excess of the mean wind speed.

Vs

The stalling speed or the minimum steady flight speed at which the airplane is controllable.

Vs1

The Stalling Speed or The minimum steady flight speed obtained in a specific configuration.

VSBY

Visibility. The ability, as determined by atmospheric conditions and expressed in units of distance, to see and identify prominent unlighted objects by day and prominent lighted objects by night.

VSI

Vertical Speed Indicator.

Vso

The Stalling Speed or The minimum steady flight speed in the landing configuration.

Vso

The stalling speed or the minimum steady flight speed in the landing configuration. In small airplanes, this is the power-off stall speed at the maximum landing weight in the landing configuration (gear and flaps down). The lower limit of the white arc.

Vsr

Reference Stall Speed.

Vsr0

Reference Stall Speed In The Landing Configuration.

Vsr1

Reference Stall Speed In A Specific Configuration.

VTOL Aircraft

Vertical Takeoff And Landing Aircraft.

VV

Vertical Visibility

VVI

Vertical Velocity Indicator

Vx

Speed For Best Angle Of Climb.

Vx

Best angle-of-climb speed. The airspeed at which an airplane gains the greatest amount of altitude in a given distance. It is used during a short-field takeoff to clear an obstacle.

Vy

Speed For Best Rate Of Climb.

Vy

Best rate-of-climb speed. This airspeed provides the most altitude gain in a given period of time.

WAAS

Wide Area Augmentation System

WAC

World Aeronautical Chart Discontinued on June 25, 2015

Wake Turbulence

Wingtip vortices that are created when an airplane generates lift. When an airplane generates lift, air spills over the wingtips from the high pressure areas below the wings to the low pressure areas above them. This flow causes rapidly rotating whirlpools of air called wingtip vortices or wake turbulence.

Warning area

A warning area is airspace of defined dimensions, extending from 3 nautical miles outward from the coast of the United States, that contains activity that may be hazardous to nonparticipating aircraft. The purpose of such warning areas is to warn nonparticipating pilots of the potential danger. A warning area may be located over domestic or international waters or both.

Waypoint

A predetermined geographical position used for route/instrument approach definition, progress reports, published VFR routes, visual reporting points or points for transitioning and/or circumnavigating controlled and/or special use airspace, that is defined relative to a VORTAC station or in terms of latitude/longitude coordinates.

WCA

Wind Correction Angle.

Weather Advisory

In aviation weather forecast practice, an expression of hazardous weather conditions not predicted in the area forecast, as they affect the operation of air traffic and as prepared by the NWS.

Weathervane

The tendency of the aircraft to turn into the relative wind.

Weight

The force exerted by an aircraft from the pull of gravity.

Weight-shift-control aircraft

A powered aircraft with a framed pivoting wing and a fuselage controllable only in pitch and roll by the pilot’s ability to change the aircraft’s center of gravity with respect to the wing. Flight control of the aircraft depends on the wing’s ability to flexibly deform rather than the use of control surfaces.

WGS-84

World Geodetic System of 1984

Wheelbarrowing

A condition caused when forward yoke or stick pressure during takeoff or landing causes the aircraft to ride on the nosewheel alone.

When Able

When used in conjunction with ATC instructions, gives the pilot the latitude to delay compliance until a condition or event has been reconciled. Unlike “pilot discretion,” when instructions are prefaced “when able,” the pilot is expected to seek the first opportunity to comply. Once a maneuver has been initiated, the pilot is expected to continue until the specifications of the instructions have been met. “When able,” should not be used when expeditious compliance is required.

Wide area augmentation system (WAAS)

A differential global positioning system (DGPS) that improves the accuracy of the system by determining position error from the GPS satellites, then transmitting the error, or corrective factors, to the airborne GPS receiver.

Wilco

I have received your message, understand it, and will comply with it.

Wind correction angle (WCA)

The angle between the desired track and the heading of the aircraft necessary to keep the aircraft tracking over the desired track.

Wind Direction Indicators

Indicators that include a wind sock, wind tee, or tetrahedron. Visual reference will determine wind direction and runway in use.

Wind Shear

A change in wind speed and/or wind direction in a short distance resulting in a tearing or shearing effect. It can exist in a horizontal or vertical direction and occasionally in both.

Windsock

A truncated cloth cone open at both ends and mounted on a freewheeling pivot that indicates the direction from which the wind is blowing.

Wings

Airfoils attached to each side of the fuselage and are the main lifting surfaces that support the airplane in flight.

Wingtip vortices

The rapidly rotating air that spills over an airplane’s wings during flight. The intensity of the turbulence depends on the airplane’s weight, speed, and configuration. Also referred to as wake turbulence. Vortices from heavy aircraft may be extremely hazardous to small aircraft.

WMS

Wide-Area Master Station

Words Twice

A. As a request: “Communication is difficult. Please say every phrase twice.”
B. As information: “Since communications are difficult, every phrase in this message will be spoken twice.”

Work

A measurement of force used to produce movement.

World Aeronautical Charts (WAC) (1:1,000,000)

Provide a standard series of aeronautical charts covering land areas of the world at a size and scale convenient for navigation by moderate speed aircraft. Topographic information includes cities and towns, principal roads, railroads, distinctive landmarks, drainage, and relief. Aeronautical information includes visual and radio aids to navigation, airports, airways, restricted areas, obstructions, and other pertinent data. Discontinued.

WP

Waypoint

WRS

Wide-Area Ground Reference Station

Z

Zulu Time. Another term used to designate Coordinated Universal Time (UTC), the standard time common to every place in the world. Formerly and still widely called Greenwich Mean Time (GMT) and also World Time, UTC nominally reflects the mean solar time along the Earth´s prime meridian.

Zone of confusion

Volume of space above the station where a lack of adequate navigation signal directly above the VOR station causes the needle to deviate.

Zulu time

A term used in aviation for coordinated universal time (UTC) which places the entire world on one time standard.

Restrict the list to specific categories by clicking on the menubar at the top of the screen.