ADF Bearing
The direction to or from a Non-Directional Beacon as indicated by the aircraft's Automatic Direction Finder equipment, relative to the aircraft's heading.
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Navigation
Browse Navigation terms for pilots, air traffic controllers, cabin crew and aviation learners.
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After Waypoint
A routing or procedural instruction indicating action to be taken immediately after passing a specified navigation fix.
View termAltitude Constraint
A published or assigned restriction that requires an aircraft to cross a specific point at, above, or below a certain altitude, common in RNAV and STAR procedures.
View termArc
A segment of a circle at a fixed distance from a navigation aid, usually flown as part of a procedure turn, approach, or missed approach using DME or RNAV guidance.
View termArea Navigation
A method of navigation allowing aircraft operation on any desired flight path within the coverage of navigation aids or within the limits of self-contained aids, or a combination of these.
View termATS Airway
A defined corridor in controlled airspace designated for the use of aircraft flying under Air Traffic Services, with specified route, width, and flight levels.
View termBearing/Distance Fix
A specified position defined by the intersection of a bearing from a navigation aid and a measured distance, used for fixes, approaches, and reporting points.
View termCourse
The intended direction of flight expressed as an angle from North, along which an aircraft is to be flown.
View termCritical Point
A position along a route where, in the event of an emergency or abnormal situation, a decision must be made to proceed or return, often used in fuel or performance-critical calculations, such as the point beyond which it is safer or faster to continue than to turn back.
View termDirect Entry
A holding entry method where the aircraft flies directly onto the inbound leg of the holding pattern upon crossing the fix.
View termDirect To
A clearance to fly directly from the present position to a specified navigation fix or waypoint, bypassing intervening fixes or published routes.
View termDistance
The measured space between two points, often in nautical miles in aviation contexts.
View termDistance Measuring
The process of determining distance, often by reference to DME (Distance Measuring Equipment) in ATC phraseology.
View termDistance Measuring Equipment
Airborne interrogator and ground transponder pair providing slant-range distance to the station in nautical miles.
View termDistance Rings
Circular overlays on a navigation display or chart, spaced at regular intervals from a reference point or airport, used for situational awareness and range estimation.
View termDistance To Go
The remaining distance to a specified point along the planned route, as displayed on the flight management system or requested by ATC for position reports.
View termDME Arc
A curved flight path at a constant distance from a DME station, commonly used in instrument approach procedures to transition from en route to the final approach course.
View termEqual Time Point
A calculated position along the planned route where the time required to continue to a suitable alternate aerodrome is the same as the time required to return to a different suitable alternate aerodrome, considering wind and performance.
View termExtended-range Twin-engine Operations Entry Point
The geographic position from which an aeroplane on an approved extended-range twin-engine operation (ETOPS) flight enters a phase requiring adherence to ETOPS requirements, such as designated diversion procedures and specific fuel, performance, and alternate airport planning.
View termFinal Approach Fix
A designated point in an instrument approach from which the final approach segment to the runway begins.
View termFlight Management System
An integrated avionics system that automates flight planning, navigation, performance, and guidance calculations throughout all phases of flight.
View termGlide Slope
The vertical guidance component of an Instrument Landing System (ILS) that provides the optimal descent path to the runway threshold.
View termGlobal Positioning System
A satellite-based navigation system providing accurate position, velocity, and time information to aircraft and other users.
View termGPS Approach
An instrument approach procedure that uses signals from the Global Positioning System (GPS) for navigation and guidance to a runway, as published on authorized approach charts.
View termGrid Navigation
A navigation technique using a grid reference system rather than true or magnetic north, primarily in polar regions where magnetic compasses and conventional charts are unreliable. Used for plotting and ATC reporting.
View termHeading
The direction in which an aircraft’s nose is pointed, expressed in degrees from North. May differ from track due to wind drift.
View termHolding Entry
The initial maneuver by which an aircraft enters a holding pattern as prescribed, using one of the approved entry procedures: direct, teardrop, or parallel.
View termHolding Fix
A specified point, identified by navigation aids or coordinates, at which an aircraft may be instructed to hold.
View termHorizontal Situation Indicator
A cockpit instrument that displays aircraft position relative to navigation aids and selected course, combining heading and navigation information for situational awareness.
View termInbound Leg
The segment of a holding pattern or approach procedure flown toward the fix or navigation aid, typically timed or distance-limited.
View termInertial Navigation System
A self-contained navigation system that determines aircraft position and velocity by processing accelerations and rotations measured by onboard sensors.
View termInertial Reference System
A subsystem of an INS providing attitude, position, and velocity reference information for aircraft systems and crew.
View termInitial Approach Fix
A designated point where an aircraft initiates the instrument approach procedure for a specific approach segment, leading towards final approach.
View termInstrument Landing System
Precision approach aid providing lateral (localizer) and vertical (glide slope) guidance to a runway.
View termIntercept
A maneuver where an aircraft joins a specified course, radial, localizer, track, or route as instructed by ATC, commonly used during approaches and vectoring.
View termIntersection
A point defined by the crossing of two or more airways, radials, or routes, used as a reference for navigation or reporting.
View termJet Route
A designated airway in controlled airspace, typically for aircraft operating at high altitudes (usually above FL180 in the US), used primarily by jet aircraft.
View termLASER Waypoint
A specifically named waypoint (LASER) used in navigation or published procedures, commonly appearing in STARs, SIDs, or enroute charts as part of ATC routing.
View termLateral Navigation
A component of navigation relating to the aircraft's position in the horizontal plane (track), including guidance along a defined route or to a waypoint.
View termLateral Navigation and Vertical Navigation
A navigation mode providing both horizontal (lateral) and vertical guidance to the aircraft, commonly used in RNAV and RNP procedures, enabling precise 3D path tracking.
View termLatitude and Longitude Coordinates
A geographic position expressed in degrees, minutes, and seconds or decimal degrees, specifying a point north or south of the Equator (latitude) and east or west of the Prime Meridian (longitude); used for precise aircraft navigation and reporting.
View termLocalizer
The component of an Instrument Landing System (ILS) that provides lateral guidance to align the aircraft with the runway centerline during approach.
View termLocalizer Performance with Vertical Guidance
An instrument approach procedure (APV) that provides both lateral and vertical guidance using satellite-based augmentation systems, similar to ILS precision but based on GPS/WAAS signals.
View termMagnetic Course
The direction of flight over the ground with respect to magnetic north, obtained by correcting true course for magnetic variation.
View termMagnetic Variation
The angular difference between true north and magnetic north at a specific location. Used to calculate magnetic headings and courses for navigation and ATC procedures.
View termMarker Beacon
A radio transmitter used in the ILS to provide pilots with range information along the approach path, typically located at specified distances from the runway threshold.
View termMissed Approach Point
A specified point in an instrument approach procedure at which a missed approach must be initiated if the required visual reference to continue the approach has not been established.
View termNavigation Fix
A specific geographical position determined by visual reference, radio aid, or satellite, used in defining air routes, procedures, or as a reporting point.
View termNext Waypoint
The upcoming predefined navigation fix along a flight route, as programmed in the flight management system and used for position reporting, routing, or sequencing.
View termNon-Directional Beacon
Low-frequency radio beacon transmitting a non-directional signal that pilots track with an ADF receiver.
View termNorth Atlantic Track
A published daily route system over the North Atlantic, providing organized and coordinated tracks for transatlantic flights to maximize safety and efficiency.
View termOceanic Track
A published route across oceanic airspace, usually coordinated daily, which enables safe and efficient passage of aircraft between continents over oceans.
View termOffset
A lateral deviation from a published route, airway, or track, authorized by ATC to avoid weather, traffic, or other hazards, typically specified in nautical miles right or left.
View termORA Waypoint
A published, named navigation point (ORA) used in RNAV procedures, typically representing a specific fix for routing, entry, or transition, defined by coordinates and used in flight management systems.
View termOutbound Leg
The segment of a holding pattern or procedure flown away from the holding fix or navigation aid, typically timed or distance-limited.
View termParallel Entry
A method of entering a holding pattern where the aircraft initially flies outbound parallel to the holding course, then turns back to intercept the inbound leg.
View termParallel Offset
A specific type of offset in which the aircraft flies a route parallel to the original track, usually by a set number of nautical miles left or right, as instructed by ATC.
View termPerformance-Based Navigation
A navigation specification that requires aircraft to meet specific performance requirements for accuracy, integrity, continuity, and functionality in accordance with ICAO Doc 9613, applied to area navigation (RNAV) and required navigation performance (RNP) operations.
View termPoint of No Return
The specific point on the route after which an aircraft does not have sufficient fuel to return to the departure aerodrome, requiring it to continue to the destination or an alternate.
View termRadio Magnetic Indicator
An instrument displaying the aircraft's bearing to selected radio navigation aids, combining magnetic heading and bearing information, commonly used with ADF or VOR.
View termRequired Navigation Performance
A statement of the navigation performance accuracy necessary for operation within a defined airspace, expressed as a numerical value that aircraft must meet or exceed.
View termRequired Navigation Performance Authorization Required
A navigation specification for RNAV operations that requires special aircrew and aircraft authorization before use, typically for advanced RNP approaches and routes.
View termRNAV Route
A published airway or route defined by area navigation (RNAV) waypoints, allowing aircraft to fly direct between points without reliance on ground-based navigation aids.
View termSequencing
The process of arranging aircraft in a specific order for arrival, approach, or departure, ensuring safe and efficient flow of air traffic.
View termStandard Instrument Departure
A published IFR departure procedure providing specific routing, altitude, and navigational guidance for departing aircraft from an airport under instrument flight rules.
View termStandard Terminal Arrival Route
A published IFR route that provides standardized lateral and vertical guidance for arriving aircraft from the en-route structure to a point where an approach to landing can begin, typically within terminal airspace.
View termStep Climb
A series of planned altitude increases during cruise, typically due to decreasing aircraft weight from fuel burn, allowing for more efficient flight profiles and compliance with ATC or route requirements.
View termTactical Air Navigation
A military navigation system (TACAN) providing bearing and distance information to aircraft, functionally similar to VOR/DME but used mainly for military operations.
View termTeardrop Entry
A method of entering a holding pattern in which the aircraft initially flies outbound on a course 30 degrees offset from the holding inbound leg, then turns inbound to intercept the holding course.
View termThreshold Crossing Height
The height above runway threshold at which the aircraft’s glide path crosses the runway during final approach, typically referenced in ILS and LPV procedures.
View termTime To Station
The calculated or measured time remaining to reach a radio navigation aid, waypoint, or fix, used for position reporting and navigation accuracy.
View termTop of Climb
The calculated point along the flight path where an aircraft completes its climb and levels off at cruising altitude as programmed in the FMS.
View termTop of Descent
The calculated point along a flight path where the aircraft begins its planned descent from cruise altitude toward the destination, as programmed in the FMS.
View termTrack
The aircraft’s actual path over the ground, measured in degrees from North. Distinct from heading, which is the direction the nose points.
View termTransition
A published route or procedure that connects the en-route structure to an instrument approach or departure, often used to link an arrival or departure with a standard terminal procedure.
View termTrue Course
The intended direction of flight over the ground referenced to true north, prior to adjustment for wind, magnetic variation, or compass error.
View termUpper ATS Airway
A designated corridor in controlled airspace, typically above a specified flight level (e.g., FL245), for use by aircraft under Air Traffic Services, forming part of the upper air route network.
View termVector
A heading assigned by ATC to an aircraft for navigation or separation purposes, usually stated as 'fly heading…'. Vectors are used for traffic sequencing, approach, or avoidance.
View termVertical Navigation
A component of navigation relating to an aircraft's position in the vertical plane (altitude), including climb, cruise, and descent profiles.
View termVHF Omnidirectional Range
Ground-based VHF radio beacon providing 360-degree azimuth guidance to aircraft.
View termVOR and TACAN Co-located Station
A ground-based radio navigation aid where a VHF Omnidirectional Range (VOR) and a Tactical Air Navigation (TACAN) facility are located at the same site, providing both civil and military navigation signals (VORTAC).
View termVOR Radial
A specific magnetic bearing from a VOR station, identified by its radial number, used for aircraft navigation and ATC instructions.
View termVOR with Co-located DME
A navigation aid installation where a VHF Omnidirectional Range (VOR) and Distance Measuring Equipment (DME) are located at the same site, providing both azimuth and distance information.
View termWaypoint
A specified geographical location, defined by coordinates, used for navigation and flight planning, including RNAV procedures.
View termZulu Time
The standard time reference used in aviation and military operations, equivalent to Coordinated Universal Time (UTC), denoted by the letter Z (Zulu) after the time.
View term