Aviation English
Aviation English Glossary
1237 professional aviation english terms with definitions, pronunciation and examples. Learn what each term means — free with Termify.
A
- What is A-Level Maintenance Inspection? A scheduled, routine maintenance check performed at regular intervals to ensure the continued airworthiness of the aircr...
- What is Abnormal Control Law? A rare fallback flight control law in fly-by-wire aircraft used under severe system failures where no flight envelope pr...
- What is Abnormal Procedure? A specific set of steps followed by pilots to address system malfunctions or unusual situations not classified as emerge...
- What is Abort takeoff? To stop the takeoff procedure after it has begun but before the aircraft becomes airborne.
- What is above ground level? An altitude or height measured with reference to the underlying ground surface directly beneath the aircraft.
- What is Accelerate-go distance required? Distance needed to accelerate to decision speed, experience an engine failure and continue take-off to 35 ft above runwa...
- What is Acceleration altitude? The specified altitude after take-off at which an aircraft transitions from take-off power and climb profile to accelera...
- What is Acknowledge? An instruction to confirm that a message has been received and understood.
- What is actuator control electronics? Boeing system managing flight control actuator signals for surface movement, including redundancy and fault isolation.
- What is ADF Bearing? The direction to or from a Non-Directional Beacon as indicated by the aircraft's Automatic Direction Finder equipment, r...
- What is ADIRS-1 inoperative? Primary ADIRS channel 1 failed; aircraft relying on remaining or standby navigation sources in accordance with MEL.
- What is Advance Crew Rest? A scheduled rest period before or during a flight, provided to designated crew members to meet fatigue management or reg...
- What is Aerodrome field elevation? The official elevation of an aerodrome above mean sea level, usually measured at the highest point of the landing area.
- What is Aeronautical Radio Incorporated 664 Aircraft Data Network? ARINC 664, also known as AFDX, is a deterministic Ethernet network protocol for reliable, high-speed data communications...
- What is Affirm? A standard radiotelephony term meaning 'Yes'; used to indicate a positive response to a question or instruction.
- What is Aft Centre Tank? A fuel tank located in the rear centre section of the aircraft fuselage, used for fuel storage and distribution during l...
- What is After Waypoint? A routing or procedural instruction indicating action to be taken immediately after passing a specified navigation fix.
- What is aileron trim? A flight-control adjustment that sets ailerons to correct lateral imbalance and maintain wings-level flight.
- What is Air Conditioning Pack Trip? An automatic or commanded shutdown of an air conditioning pack due to overtemperature, overpressure, or system fault, im...
- What is Air rage? An incident involving violent, disruptive or aggressive passenger behaviour during flight, endangering safety or order o...
- What is Air start unit? A device used to start an aircraft's engines by supplying high-pressure air.
- What is Air-Conditioning Pack Inoperative? Indicates a failure of an air-conditioning pack, possibly affecting cabin pressurization and requiring MEL compliance be...
- What is air-data inertial reference unit? An advanced aircraft system combining air data sensors and inertial reference to provide navigation and performance data...
- What is air-data reference? Aircraft module collecting and providing airspeed, altitude, and temperature data from external probes.
- What is Air-Traffic Spacing Tool? A controller support system that calculates optimal spacing between arriving and departing aircraft to maximize runway e...
- What is Aircraft Network Security? Protection of aircraft networks from unauthorized access, cyberattacks, and data breaches, ensuring the integrity of onb...
- What is Airside? The part of an airport accessible to aircraft, including runways, taxiways, and ramps, but restricted to authorized pers...
- What is Airworthiness directive logged? Mandatory compliance record entered in technical log documenting completion of authority-issued safety directive.
- What is ALL CLEAR? Final ramp-crew signal that all personnel, equipment and pin checks are complete; aircraft environs safe for taxi or eng...
- What is Alpha? The letter 'A' as spoken in the ICAO phonetic alphabet to avoid confusion in radio communications.
- What is Alpha-Floor Protection? Autothrust safeguard that commands maximum thrust if angle-of-attack approaches stall, preventing loss of lift.
- What is Alternate Brake System? A backup braking system used when the primary brake system fails or becomes unavailable.
- What is Alternate Control Law? A degraded mode in fly-by-wire aircraft providing limited flight envelope protections, used when normal law is lost due ...
- What is Alternate Diversion Field? An airport selected in the flight plan to which an aircraft may proceed when landing at the destination becomes inadvisa...
- What is Alternate exit? A secondary or backup emergency exit designated for use when a primary exit is unusable during evacuation.
- What is alternate landing-gear extension? A backup method to deploy the landing gear using gravity, hydraulic, or manual means if the normal extension system fail...
- What is Alternate procedure required? Standard operating sequence unavailable; crew must follow officially published alternate or contingency checklist.
- What is Alternate Threshold Fuel? The predetermined minimum fuel required at an alternate airport's landing threshold, ensuring safe diversion in case a l...
- What is Alternate-airport fuel? The required fuel quantity to fly from the destination airport to a designated alternate airport, including approach and...
- What is Altimeter set? Confirms that the aircraft's altimeter has been adjusted to the correct barometric pressure setting, as assigned by ATC ...
- What is Altimeter setting? The value to which the scale of a pressure altimeter is set so as to indicate elevation or height. In ATC phraseology, t...
- What is Altimeter Setting? The current local atmospheric pressure value set in an aircraft’s altimeter to ensure correct indication of altitude abo...
- What is Altimeter setting referenced to mean-sea-level pressure? The altimeter subscale setting so that the instrument indicates altitude above mean sea level. Also known as QNH.
- What is Altimeter Setting to Aerodrome Elevation? The altimeter setting that displays the elevation of the aerodrome as the altitude on the altimeter when on the ground. ...
- What is Altimeter Setting to Mean Sea Level Pressure? The altimeter setting that corresponds to the atmospheric pressure at mean sea level. Referred to as QNH in ICAO phraseo...
- What is Altimeter Setting Using Standard Pressure? An altimeter setting based on the standard pressure of 1013.25 hPa or 29.92 inHg, used above the transition altitude. Kn...
- What is Altitude? The height of an aircraft above sea level, usually expressed in feet.
- What is Altitude check? A request to verify the current altitude of the aircraft.
- What is Altitude Constraint? A published or assigned restriction that requires an aircraft to cross a specific point at, above, or below a certain al...
- What is Altitude restriction? A specified altitude that an aircraft must not exceed or descend below.
- What is altocumulus castellanus cloud? Medium-level turreted cloud with rising towers indicating mid‑level instability, possible precursor to thunderstorms.
- What is Anti-collision lights? High-intensity red or white lights installed on an aircraft and activated before engine start and during all movement to...
- What is Anti-ice valve failure? Malfunction of wing or engine anti-ice valve preventing hot-air flow, compromising ice protection and requiring flight p...
- What is Anti-icing? Preventive treatment applied to aircraft surfaces to inhibit the formation of ice during flight or ground operations, us...
- What is Antiskid System Inoperative? A condition where the antiskid braking system is not operational, requiring alternate braking procedures and possible pe...
- What is anti‑icing? Application of fluid to prevent ice formation during ground operations or flight.
- What is Approach Climb Requirement? The minimum climb gradient that an aircraft must meet during the missed approach phase, considering one engine inoperati...
- What is approach reference speed? Speed selected for use on final approach segment, ensuring safe control margin above stall but stable profile.
- What is Apron? A defined area on an airport intended to accommodate aircraft for purposes of loading or unloading passengers or cargo, ...
- What is APU automatic start sequence? A programmed series of actions by which the auxiliary power unit starts automatically and safely without crew interventi...
- What is APU fuel feed? The dedicated fuel supply system or operation that delivers fuel from the aircraft's tanks to the Auxiliary Power Unit (...
- What is Arc? A segment of a circle at a fixed distance from a navigation aid, usually flown as part of a procedure turn, approach, or...
- What is Area Forecast for Low-Level Flights? A GAMET area forecast describing significant weather below FL100 (or FL150 over mountainous terrain) within a FIR, suppo...
- What is Area Navigation? A method of navigation allowing aircraft operation on any desired flight path within the coverage of navigation aids or ...
- What is Area Navigation Required Navigation Performance? A navigation specification for aircraft that combines Area Navigation (RNAV) with defined Required Navigation Performanc...
- What is Assist handle? A fixed handhold installed near exits or on evacuation slides to aid crew and passengers in maintaining balance or facil...
- What is ASU connected? Confirmation that the Air Start Unit is attached and supplying pneumatic power for engine start procedures on the ground...
- What is ATA chapter reference? Standardized reference number identifying aircraft system/component according to the ATA 100/2200 maintenance coding sys...
- What is Atmospheric Sounding? A vertical profile of the atmosphere obtained by balloon or remote sensing, recording temperature, humidity, wind, and p...
- What is ATS Airway? A defined corridor in controlled airspace designated for the use of aircraft flying under Air Traffic Services, with spe...
- What is auto-brake system? A system that automatically applies braking at a selected rate during landing or rejected take-off to optimize stopping ...
- What is Automated external defibrillator? A portable device that analyzes cardiac rhythm and delivers electrical shocks to restore normal heart rhythm during card...
- What is Automated External Defibrillator? A portable device used to deliver an electric shock to restore normal heart rhythm during sudden cardiac arrest on board...
- What is Automated Weather Observing System? An unattended station that continuously measures and broadcasts real-time surface weather elements to pilots and ATC on ...
- What is Automatic Dependent Surveillance Broadcast In? A surveillance function enabling an aircraft to receive and display ADS-B broadcasts from other aircraft, increasing sit...
- What is Automatic Dependent Surveillance Broadcast Out? A surveillance technology in which an aircraft automatically broadcasts its position, velocity, and identification deriv...
- What is Automatic Dependent Surveillance Contract? A formal agreement, electronically established between an aircraft and ATC ground station, specifying when position, int...
- What is automatic dependent surveillance–broadcast? A surveillance technology in which aircraft broadcast position and flight data, allowing real-time tracking by ATC and o...
- What is Automatic landing? A landing performed by the aircraft's autopilot system, typically using ILS signals, requiring minimal pilot input, espe...
- What is Automatic Landing System? Integrated avionics that guides aircraft from glide-slope capture through flare and rollout without pilot control inputs...
- What is Automatic Position Report? A position report transmitted automatically by onboard avionics via datalink (CPDLC or ADS-C) at predetermined waypoints...
- What is Automatic Step Climb? A flight mode or FMS function that automatically commands step climbs as aircraft weight decreases to optimize fuel effi...
- What is Automatic Terminal Information Service? A continuous broadcast of recorded aerodrome information, including weather, runways and NOTAMs, provided to reduce cont...
- What is autothrottle system? A system that automatically sets and maintains engine thrust based on flight parameters and autopilot commands.
- What is Auxiliary generator inoperative? Aircraft auxiliary power unit (APU) generator not providing electrical power, requiring external source for ground opera...
- What is auxiliary power unit? A self-contained turbine engine providing electrical and pneumatic power to the aircraft while on the ground or as backu...
- What is Auxiliary Power Unit Dispatch? Authorization for a flight to dispatch with the Auxiliary Power Unit (APU) operating or required, usually due to ground ...
- What is Auxiliary Power Unit Fire? A fire involving the auxiliary power unit, typically located in the aircraft's tail, requiring immediate shutdown and fi...
- What is Avionics Bay Smoke? Smoke detected in the avionics bay, indicating potential fire or overheating of electronic components, requiring immedia...
- What is avionics cooling system? A system providing airflow and temperature regulation to prevent overheating of aircraft avionics components.
- What is Avionics Ethernet Network? A high-speed, deterministic digital data network based on Ethernet technology, used to interconnect avionics systems on ...
- What is avionics fan? A fan dedicated to cooling avionics equipment by circulating air through the electronics bay.
- What is Avionics Full-Duplex Switched Ethernet? A deterministic, high-speed, full-duplex switched Ethernet network designed specifically for critical avionics systems, ...
B
- What is Back taxi? Taxiing on a runway in the opposite direction of takeoff or landing.
- What is Backtrack? A procedure whereby an aircraft taxis in the opposite direction of take-off or landing on a runway to reach the threshol...
- What is Baggage cart? A vehicle used to transport checked baggage between the aircraft and the terminal during ground handling operations.
- What is Balanced field length? Runway length at which accelerate-go and accelerate-stop distances are equal under specified conditions.
- What is Barometric Pressure? The atmospheric pressure as measured by a barometer, used to determine altimeter settings and to ensure altitude accurac...
- What is Base leg? The flight path at right angles to the landing runway off its approach end.
- What is basic operating weight? The weight of an aircraft including crew, unusable fuel, and all necessary fluids for operation, excluding payload and u...
- What is Bassinet position? Approved seat row and attachment point where an aircraft baby bassinet may be installed and locked.
- What is Battery-Only Power? A condition where the aircraft’s electrical system is operating solely on battery power, typically due to the failure of...
- What is Beacon on? Indicates that the aircraft's anti-collision beacon lights have been switched on, typically prior to engine start, signa...
- What is Bearing/Distance Fix? A specified position defined by the intersection of a bearing from a navigation aid and a measured distance, used for fi...
- What is Belt loader? A motorized vehicle equipped with a conveyor belt for loading and unloading baggage or cargo into aircraft holds.
- What is Belt power on? Controller or ramp-agent confirmation that the motorised baggage conveyor belt is energised and ready for loading or off...
- What is Beta-Target Protection? Flight-laws function holding safe sideslip target during engine-out or crosswind approach to maintain directional contro...
- What is Beverage cart? A service cart used by cabin crew to serve drinks and light refreshments to passengers during the flight, stowed in the ...
- What is Beverage drawer? A dedicated sliding compartment in the aircraft galley for storing drinks, ice, and related service items, accessible to...
- What is Big Data Analytics? The use of advanced computing techniques to analyze vast amounts of operational data, supporting safety, efficiency, and...
- What is Biological Clock? The natural internal time-keeping system that regulates physiological activities, directly affecting crew alertness and ...
- What is Bird Strike? A collision between an aircraft and one or more birds, often occurring during takeoff or landing and potentially affecti...
- What is bleed air? High-pressure air extracted from an aircraft engine's compressor stage and used for environmental control, pressurizatio...
- What is Bleed Air Leak? An unintended escape of high-pressure air from the aircraft bleed air system, which may affect pressurization, anti-ice,...
- What is bleed overpressure? A condition where the bleed air pressure exceeds safe limits, causing automatic shutdown or system warnings.
- What is bleed trip? Automatic closure of bleed air supply due to over-temperature or over-pressure, protecting the system from damage.
- What is Bleed-Off Take-off? A take-off performed with engine bleed air turned off to optimize thrust, typically when performance-limited.
- What is Blending ratio? The specified proportion of de-icing or anti-icing fluid mixed with water to achieve optimal performance under prevailin...
- What is Block fuel? The total quantity of fuel loaded on board the aircraft before engine start, including fuel for taxi, flight, alternate,...
- What is Block time? The total elapsed time from when the aircraft first moves under its own power for departure until it finally stops after...
- What is Blocked exit? An emergency exit or cabin door that cannot be used for evacuation due to obstruction, damage, or outside hazards.
- What is Blown Tyre? A condition where an aircraft tyre bursts during taxi, take-off, or landing, possibly affecting braking or steering.
- What is blue hydraulic system? One of three Airbus hydraulic systems, providing redundancy for flight controls, landing gear, and other powered compone...
- What is Bomb Threat? A reported or suspected presence of an explosive device on board an aircraft or within the airport area.
- What is Bonding cable? Flexible conductor that equalises electrical potential between aircraft and refueling equipment to prevent static discha...
- What is Boost pump? An electrically or hydraulically operated pump used to supply fuel under pressure from tanks to engines, especially duri...
- What is Borescope Engine Inspection? A maintenance procedure using a borescope device to visually inspect the internal components of an aircraft engine for d...
- What is Brace Position? A body position adopted by passengers and crew to minimize injury during an imminent impact or emergency landing, as per...
- What is Brake Energy Limit? The maximum energy that aircraft brakes can safely absorb during landing or rejected takeoff, determined by aircraft wei...
- What is Brake Overheat? A situation in which the aircraft's braking system exceeds safe operating temperatures, potentially reducing effectivene...
- What is Brake Wear? The condition in which the aircraft’s brake components have undergone material loss due to repeated use, requiring monit...
- What is brake-temperature monitor? A cockpit display or system that monitors the temperature of the main landing-gear brakes to prevent overheating.
- What is braking action? Pilot- or airport-reported assessment of runway surface stopping quality: good/medium/poor/nil.
- What is Bravo? The letter 'B' as spoken in the ICAO phonetic alphabet to ensure clarity in radio communications.
- What is Bulk hold? Small aft or forward lower-deck compartment used for loose bags, live animals, or outsized items not loaded in container...
- What is Bunk Rest Period? A scheduled period during a flight in which a crew member is off duty and resting in a designated bunk or crew rest faci...
- What is Bypass pin? A safety locking pin inserted into the nose gear steering system to disable nose wheel steering during towing or pushbac...
C
- What is C-Level Maintenance Inspection? A comprehensive periodic maintenance inspection performed at longer intervals than A- or B-Checks, involving in-depth sy...
- What is Cabin baggage? Passenger-carried items stowed in the aircraft cabin, normally in overhead bins or under seats, and subject to weight/si...
- What is Cabin crew briefing card? Card summarising aircraft type-specific emergency duties used during crew pre-flight briefing.
- What is Cabin Depressurization? A sudden or gradual loss of cabin pressure, requiring immediate response such as emergency descent and oxygen use.
- What is Cabin Evacuation? An emergency procedure where passengers and crew exit the aircraft rapidly using all available exits, typically initiate...
- What is cabin intercommunication system? An integrated system enabling voice communication between cabin crew and cockpit, and among crew stations.
- What is Cabin interphone? An internal aircraft communication system that enables direct, secure voice communication between cabin crew, cockpit cr...
- What is Cabin lighting panel? Flight attendant control panel for selecting cabin lighting modes, intensity and colour settings.
- What is Cabin Log Defect? A discrepancy, malfunction, or abnormality reported by crew and recorded in the aircraft cabin log for maintenance atten...
- What is Cabin logbook? The official record kept on board for documenting all technical, operational, or passenger-related events and discrepanc...
- What is Cabin pressure? The controlled air pressure within an aircraft cabin, maintained to ensure passenger safety and comfort at altitude.
- What is cabin pressure controller? Automatic device that regulates cabin altitude and rate of pressure change by controlling the outflow valve.
- What is Cabin pressure controller 1 inoperative? Primary automatic pressurization channel failed; crew managing cabin differential in manual mode per QRH procedures.
- What is Cabin ready? A standardized phrase indicating that the cabin has been fully prepared for takeoff, landing, or other specified phase o...
- What is Cabin secure? A procedural phrase indicating that all passengers are seated, seatbelts fastened, and the cabin is safe for taxi, takeo...
- What is Cabin secure? Formal statement by cabin crew that all safety checks are completed, all items stowed, doors armed, and the cabin is rea...
- What is Cabin Secure Check? A safety verification by cabin crew to ensure passengers are seated, seat belts fastened, cabin items stowed, and emerge...
- What is Cabin Smoke? Presence of smoke in the passenger or flight deck cabin, indicating potential fire requiring immediate attention.
- What is Cabin temperature control? Panel or system regulating passenger-cabin temperature by mixing conditioned bleed air and recirculated flow.
- What is calibrated airspeed? Indicated airspeed corrected for instrument and position errors, used for accurate performance calculations.
- What is Call light? An indicator light in the aircraft cabin that signals a passenger is requesting crew assistance.
- What is Cancel IFR? An instruction to terminate the Instrument Flight Rules flight plan.
- What is Cancel SID? An instruction to terminate the Standard Instrument Departure procedure.
- What is Cancel STAR? An instruction to terminate the Standard Terminal Arrival Route procedure.
- What is Cancel takeoff? An instruction to abort the takeoff procedure before the aircraft becomes airborne.
- What is Cargo Compartment Fire? A detected or suspected fire in the aircraft's cargo hold, requiring immediate fire suppression and emergency procedures...
- What is Cargo dolly? A small wheeled platform or trailer used on the ramp to transport ULDs, baggage containers, or cargo pallets between air...
- What is Cargo door? Large exterior hinged or plug-type door on the aircraft fuselage used for loading and unloading freight or baggage conta...
- What is Cargo pallet? A flat transport structure used as a base for Unit Load Devices (ULDs) or loose cargo, designed to be moved by forklifts...
- What is Carry-on luggage? Passenger items approved to remain with the traveler in the cabin and stowed under-seat or in overhead bins.
- What is category A? A Minimum Equipment List category requiring rectification of an inoperative item within a time period specified in the M...
- What is category B? A Minimum Equipment List category requiring rectification of an inoperative item within three consecutive calendar days,...
- What is category C? A Minimum Equipment List category requiring rectification of an inoperative item within ten consecutive calendar days, e...
- What is category D? A Minimum Equipment List category requiring rectification of an inoperative item within 120 consecutive calendar days, e...
- What is Catering uplift? The process of loading all required food, beverages, and associated service items onto an aircraft prior to departure, c...
- What is Catering vehicle? A ground service vehicle used to deliver food and beverages to an aircraft, typically accessing the rear or forward serv...
- What is ceiling? Height above ground at which an unbroken or overcast cloud layer exists.
- What is Center Gravity Management? The active process of monitoring and controlling the aircraft’s center of gravity throughout all flight phases to ensure...
- What is Center tank? The main fuel tank located in the central section of an aircraft’s fuselage, typically used before the wing tanks.
- What is Certified release to service? Formal written declaration by licensed engineer that aircraft or component is airworthy and fit for return to operation.
- What is CG shift? Change in the aircraft’s centre of gravity caused by fuel burn, cargo movement or passenger redistribution, potentially ...
- What is Charlie? The letter 'C' as spoken in the ICAO phonetic alphabet, used for clarity in radio communications.
- What is Check time? The exact recorded time at which a de-icing or anti-icing procedure is completed or a specific check (such as a pre-take...
- What is Checked baggage tag? Barcode or RFID label affixed to hold-loaded baggage to identify routing, weight and ownership.
- What is Chemical oxygen generator? A device that produces oxygen through a chemical reaction, typically used to supply emergency oxygen to passengers via d...
- What is Child Restraint Device? FAA/ICAO-approved seat or harness securing children under two for taxi, take-off, turbulence and landing.
- What is chip detector? A sensor in an engine or gearbox that detects metallic particles, indicating wear or damage to internal components.
- What is Chock clear? A confirmation from ground crew that all wheel chocks have been removed and the aircraft is clear to move.
- What is Chocks? Wedges placed in front of and behind aircraft wheels to prevent movement when parked.
- What is Circadian Offset? The difference between local time and a crew member's biological night, often considered in fatigue management and long-...
- What is Circuit? A standard rectangular traffic pattern around the airfield used for sequencing aircraft for landing or training operatio...
- What is Class One Navigation? Navigation in airspace where the position of the aircraft can be continuously determined by reference to ground-based ra...
- What is Class Two Navigation? Navigation in airspace where position cannot be reliably fixed using ground-based radio navigation aids, requiring the u...
- What is Clean config? An aircraft configuration in which all lift devices such as flaps and slats are retracted and landing gear is up, optimi...
- What is Clear Air Turbulence? Turbulence that occurs in clear air, typically at high altitudes, away from thunderstorms and not associated with visibl...
- What is Clear ice? A transparent, smooth, and hard ice layer formed by the slow freezing of supercooled water droplets on aircraft surfaces...
- What is Clear Icing? The formation of smooth, transparent ice on aircraft surfaces, resulting from slow freezing of large supercooled water d...
- What is Clear left? Visual confirmation that the aircraft’s left side is free of obstacles, vehicles or traffic before turning or taxiing.
- What is Clear of conflict? An indication that the aircraft is no longer in a conflicting situation with another aircraft.
- What is Clear right? Confirmation that the aircraft’s right side is unobstructed prior to manoeuvre, ensuring wingtip and engine clearance.
- What is clear-air turbulence? Turbulence occurring in clear skies, typically at high altitudes near the jet stream, with no visible weather phenomena.
- What is Cleared? An explicit authorization by ATC for a pilot to proceed under specified conditions within controlled airspace.
- What is Cleared approach? An instruction indicating that the aircraft is authorized to execute an approach procedure.
- What is Cleared for takeoff? An air traffic control authorization for an aircraft to depart from a specified runway, indicating that the runway is av...
- What is Cleared ILS approach? An instruction indicating that the aircraft is authorized to execute an Instrument Landing System approach.
- What is Cleared ILS approach? ATC clearance instructing an aircraft to conduct an Instrument Landing System (ILS) approach to a specified runway.
- What is Cleared RNAV approach? An instruction indicating that the aircraft is authorized to execute an RNAV approach.
- What is Cleared RNAV approach? ATC clearance authorizing an aircraft to conduct an Area Navigation (RNAV) approach procedure to a specified runway.
- What is Cleared to land? An air traffic control authorization for an aircraft to land on a specified runway, indicating that the runway is availa...
- What is Cleared visual approach? An instruction indicating that the aircraft is authorized to execute a visual approach.
- What is Cleared visual approach? ATC instruction authorizing an aircraft to proceed visually to the airport, maintaining own separation and visual contac...
- What is Cleared VOR approach? An instruction indicating that the aircraft is authorized to execute a VOR approach.
- What is clearway length? A defined rectangular area beyond the runway, free of obstructions, suitable for aircraft to continue take-off in case o...
- What is Climb and maintain? Instruction for the aircraft to begin climbing to the stated altitude and maintain that altitude when reached.
- What is Climb power? A reduced engine power setting selected after take-off and acceleration, used for the climb phase to minimize engine wea...
- What is Climb to? An instruction to initiate a climb to a specific altitude and level off upon reaching it, unless otherwise directed.
- What is Climb via? An ATC instruction to follow published climb restrictions, altitudes, and routes as depicted in a Standard Instrument De...
- What is cloud base? Lowest altitude of the visible cloud layer, reported as base of scattered, broken, overcast.
- What is Coffee maker? A dedicated appliance installed in the aircraft galley to brew hot coffee for passengers and crew. Its operation is subj...
- What is Cold Front? A weather front where a cold air mass advances and displaces a warmer air mass, often producing showers, thunderstorms, ...
- What is Cold soak? A condition in which aircraft fuel, systems, or equipment are cooled for an extended period during high-altitude flight,...
- What is Cold soak? A condition where aircraft fuel or components become extremely cold after prolonged exposure to low outside air temperat...
- What is Compass deviation? Error between magnetic compass indication and actual magnetic heading exceeding permissible limits; requires calibration...
- What is Computer-Based Training Check? A mandatory electronic assessment verifying that aircrew or ATC personnel have completed required computer-based trainin...
- What is Condition monitoring? Ongoing process of assessing system or component health through data and trend analysis to guide maintenance decisions.
- What is Configuration Deviation? A formally approved variation from the aircraft’s standard configuration as specified in the Configuration Deviation Lis...
- What is configuration deviation list? An official document specifying permissible aircraft configuration deviations that do not affect safe flight, used for d...
- What is Configuration Deviation List Item? An entry in the Configuration Deviation List authorizing dispatch with specific external or configuration deviations, wi...
- What is Configuration Deviation List Item? An authorized deviation from aircraft configuration detailed in the Configuration Deviation List, permitting dispatch wi...
- What is consecutive flights? A sequence of successive flights where certain MEL/CDL items may remain deferred or require repeated checks as specified...
- What is constant-speed drive? A transmission device that converts variable engine speed to a constant speed for generator operation.
- What is Consumable replenished? A maintenance log entry confirming replenishment of expendable items such as oil, hydraulic fluid, or oxygen.
- What is Contact approach? An IFR approach procedure that permits an aircraft under VFR conditions to proceed to the destination airport by visual ...
- What is Contact departure? ATC instruction to switch radio communication to the departure controller, usually issued shortly after takeoff for enro...
- What is Contact ground? Instruction from ATC to switch communication to the ground control frequency, typically issued after landing or before t...
- What is Contact tower? Instruction from ATC to switch radio communication from the current frequency to the aerodrome control tower frequency f...
- What is Container loader? A type of ground service equipment used to lift and load cargo containers or Unit Load Devices (ULDs) into the aircraft'...
- What is contaminated runway? Runway with >25% surface covered by standing water ≥3 mm, slush, snow, ice.
- What is Contingency Procedure? A predetermined sequence of actions to be followed when an abnormal or emergency situation occurs during flight, as defi...
- What is Continue? An ATC instruction to proceed with the current action or phase of flight without change.
- What is Continue approach? An instruction to proceed with the instrument or visual approach but not yet cleared to land.
- What is Continue climb? An ATC instruction to maintain or resume climbing to a previously assigned altitude or to a new altitude.
- What is Continue descent? An ATC instruction directing the pilot to maintain the ongoing descent to a specified level or altitude without interrup...
- What is Continue taxi? An instruction to proceed with ground movement along a designated taxi route or surface without stopping or awaiting fur...
- What is control number? A unique identifier assigned to a deferred defect, MEL/CDL item, or maintenance entry for tracking and compliance.
- What is Controller Pilot Link? A data communication system (CPDLC) used for direct exchange of messages between air traffic controllers and pilots, esp...
- What is Controller-Pilot Data Link Communications? A digital communication system that enables the exchange of messages between air traffic controllers and pilots via data...
- What is Controller-Pilot Data Link Communications? A digital communication system enabling direct message exchange between air traffic controllers and pilots via data link...
- What is Controller-Pilot Data Link Uplink Message? A digital message sent from ATC to the flight deck over the Controller-Pilot Data Link Communications (CPDLC) system, in...
- What is controller–pilot data link communications? A digital communication system enabling direct text-based exchanges between ATC and pilots via data link instead of voic...
- What is corrective action? The specific maintenance or operational step taken to resolve a defect, discrepancy, or deferred item as documented in t...
- What is Course? The intended direction of flight expressed as an angle from North, along which an aircraft is to be flown.
- What is Course (intended track)? The intended horizontal direction of travel of an aircraft over the ground, usually expressed in degrees from North.
- What is Crash axe? A robust, sharp-edged hand tool stowed in the cockpit, intended for emergency access, fire-fighting, or egress during ev...
- What is Crash axe? Cockpit-mounted emergency axe for cutting or prying during evacuation or fire-fighting operations.
- What is Crash position? A prescribed body posture adopted by crew and passengers to maximize survivability in the event of an imminent impact or...
- What is Crew Augmentation? The practice of adding qualified crew members to the flight crew to allow in-flight rest and ensure regulatory complianc...
- What is Crew duty period? The total period a crew member is on duty, including all pre-flight, in-flight, and post-flight responsibilities, regula...
- What is Crew Life Vest? High-visibility life jacket with water-activated light issued to each cabin and flight crew member.
- What is Crew Oxygen Mask Use? The action taken by flight crew to don oxygen masks during situations such as smoke, fumes, or cabin depressurization.
- What is Crew rest? A designated area on the aircraft reserved exclusively for crew members to rest or sleep during flight operations, parti...
- What is Crew restraint? Any safety device, including harness or lap belt, designed to secure flight or cabin crew members in their seats during ...
- What is Crew seat inoperative? Flight-deck seat fails to lock, adjust, or retract, potentially compromising crew safety and requiring MEL evaluation.
- What is Critical Fuel State? A situation where an aircraft's fuel supply has reached a level where it can only proceed to the intended destination an...
- What is Critical Point? A position along a route where, in the event of an emergency or abnormal situation, a decision must be made to proceed o...
- What is Critical surface? Any aircraft part essential for lift or control, including wings, control surfaces, and stabilizers, which must be clear...
- What is Cross diagonal? A painted or marked line intersecting taxiways or apron areas at an angle, indicating where to cross or not cross as ins...
- What is Cross runway? An instruction authorizing an aircraft to proceed across a specified runway, typically during taxi operations.
- What is Cross-check? The action of verifying that a safety-related task (such as arming/disarming doors) has been correctly completed by anot...
- What is Cross-check altimeters? Instructs flight crew to independently compare altimeter readings to verify correct setting and altitude indication, ens...
- What is Cross-wind component? The part of the wind velocity that is perpendicular to the runway or the aircraft's track, affecting lateral control dur...
- What is Crossfeed? A fuel system operation allowing fuel to be transferred or used from one tank to another to maintain aircraft balance or...
- What is Crosswind? The flight path at right angles to the landing runway at the upwind end.
- What is Crowd control? The actions taken by crew to maintain order, direct movement, and prevent bottlenecks during emergency evacuations or ab...
- What is Cruise? The phase of flight where the aircraft maintains a steady altitude and speed.
- What is Cruise? The phase of flight in which the aircraft maintains a steady flight level and speed along the planned route after climb ...
- What is Cruise climb? A climb technique where the aircraft climbs at a constant power setting and speed.
- What is Cruise descent? A descent at a controlled rate while maintaining cruise speed.
- What is Cruise descent? A gradual descent initiated by the pilot or ATC from cruising altitude, often to optimize fuel burn or prepare for arriv...
- What is cumulonimbus cloud? Towering vertical cloud with significant turbulence, precipitation, and lightning potential.
- What is Customer complaint? A formal expression of dissatisfaction made by a passenger regarding any aspect of airline service, safety, or comfort.
- What is Cybersecurity Hardening? The process of applying security measures to reduce cyberattack risk on aircraft systems and networks (EASA, ICAO Doc 10...
D
- What is D-Level Heavy Maintenance Inspection? An extensive, scheduled maintenance inspection that involves major disassembly, overhaul, and comprehensive structural a...
- What is Data Communications? Digital message exchange between air traffic control and aircraft, including CPDLC, ADS-C, and other datalink systems fo...
- What is Data Link Connection? A digital communications channel established between aircraft and ATC/dispatch for automatic reporting, clearances, and ...
- What is Day‑night flare? A pyrotechnic signaling device that can be used in both daylight and darkness, included in survival kits for attracting ...
- What is De-icing? The process of removing existing ice, frost, or snow from aircraft surfaces, typically wings, tail, and control surfaces...
- What is decision altitude? Specified altitude in precision approach at which a missed approach must be initiated if runway not in sight.
- What is decision distance available? Distance from threshold to point on runway where go‑around decision altitude is reached, allowing a missed‑approach befo...
- What is Decision Fuel Point? A predetermined point along the route where a decision is made to proceed to the destination or divert based on remainin...
- What is deferral? A formal process allowing a non-essential inoperative item to be left unrepaired for a specified time under MEL/CDL limi...
- What is Deferred action control? Cockpit switch or placard indicating an MEL-approved deferred maintenance item that must not be activated in flight.
- What is deferred defect report? A formal record noting a defect which has been deferred under MEL/CDL procedures, including details of rectification pla...
- What is Defuel? The process of removing fuel from an aircraft’s tanks, usually for maintenance, balancing, or to comply with regulatory ...
- What is Delayed push? Notification that pushback clearance or procedure is postponed due to operational, technical, or ATC constraints.
- What is Delta? The letter 'D' as spoken in the ICAO phonetic alphabet, used for clear identification of taxiways, holding points, or ca...
- What is density altitude? Altitude at which the aircraft feels it is flying based on current pressure, temperature, and humidity, affecting perfor...
- What is Depart via? An ATC instruction directing the pilot to follow a specified Standard Instrument Departure (SID) or route after takeoff.
- What is Dependent Surveillance Contract? A prearranged automatic reporting agreement (ADS-C) between ATC and aircraft for position, intent, and status data in re...
- What is Deportee? A person who is being sent out of a country by legal order and is being transported by air under escort or supervision.
- What is Derated Thrust? Engine rated for lower maximum take-off thrust than certification limit, permanently reducing stress and maintenance cos...
- What is Descend and maintain? An instruction to begin descent and level off at the specified altitude, maintaining it until further clearance is issue...
- What is Descend to? An instruction from air traffic control directing an aircraft to decrease altitude to a specified level.
- What is de‑icing? Removal of existing frost, ice or snow from aircraft surfaces before flight.
- What is Digital Automatic Terminal Information Service? A system that provides pre-recorded, digital, real-time airport and weather information to pilots automatically (ICAO Do...
- What is Digital Notice to Airmen? A machine-readable NOTAM provided in digital format for direct integration into flight planning, EFBs, and avionics syst...
- What is Digital Terrain and Obstacle Information Management System? A database system providing real-time digital terrain and obstacle data for flight planning, situational awareness, and ...
- What is Direct Control Law? A degraded flight control mode in fly-by-wire aircraft where control surfaces respond directly to pilot input without fl...
- What is Direct Entry? A holding entry method where the aircraft flies directly onto the inbound leg of the holding pattern upon crossing the f...
- What is Direct To? A clearance to fly directly from the present position to a specified navigation fix or waypoint, bypassing intervening f...
- What is Disarm doors? To set aircraft doors to a disarmed mode so that evacuation slides will not deploy when the door is opened.
- What is Disembarkation? The controlled process of passengers and crew leaving the aircraft at the end of a flight, following standard operating ...
- What is Disengage towbar? Ground-crew command to release the towbar from the aircraft nose-gear after pushback is complete and brakes set.
- What is dispatch deviation? An authorized variation from standard aircraft configuration or equipment status, documented for legal dispatch of a fli...
- What is Dispatch limitation? Restrictive condition under which an aircraft may be dispatched due to system defect or MEL, affecting allowable operati...
- What is Disregard? A phrase used to instruct the pilot to ignore the previous transmission.
- What is Distance? The measured space between two points, often in nautical miles in aviation contexts.
- What is Distance Measuring? The process of determining distance, often by reference to DME (Distance Measuring Equipment) in ATC phraseology.
- What is distance measuring equipment? An aircraft navigation system providing slant-range distance to a ground station, often paired with VOR or ILS.
- What is Distance Measuring Equipment? Airborne interrogator and ground transponder pair providing slant-range distance to the station in nautical miles.
- What is Distance Rings? Circular overlays on a navigation display or chart, spaced at regular intervals from a reference point or airport, used ...
- What is Distance To Go? The remaining distance to a specified point along the planned route, as displayed on the flight management system or req...
- What is Ditching? The controlled emergency landing of an aircraft on water.
- What is Diversion Fuel? The amount of fuel required to divert from planned destination to an alternate aerodrome, factoring weather, distance, a...
- What is DME Arc? A curved flight path at a constant distance from a DME station, commonly used in instrument approach procedures to trans...
- What is Door closed? Indicates that all required aircraft doors are physically closed, typically before engine start or pushback.
- What is Door open? Confirms that one or more aircraft doors are physically open, typically during boarding, deplaning, or servicing.
- What is Door status? The operational state of aircraft doors, including whether they are armed, disarmed, open, closed, locked, or unlocked, ...
- What is Door status? The current operational state of all aircraft doors—open, closed, armed, disarmed—communicated between cabin crew, fligh...
- What is Double Engine Failure? A critical emergency situation where both engines of a multi-engine aircraft cease functioning in flight.
- What is Downwind? The flight path parallel to the landing runway in the opposite direction of landing.
- What is Drift down? A procedure for descending to a safe altitude following engine failure at cruise. Aircraft descends along a planned path...
- What is Drift Down Procedure? A contingency descent profile followed after an engine failure at cruise altitude to achieve the aircraft’s new single-e...
- What is Dual Engine Flameout? A critical emergency in which both engines of an aircraft stop producing thrust due to flameout, often requiring immedia...
- What is Dual Hydraulic System Loss? A simultaneous failure of two independent hydraulic systems on an aircraft, significantly degrading control and operatio...
- What is Dual-lane slide? Evacuation slide designed with two parallel lanes to expedite passenger egress on wide-body aircraft exits.
- What is duty-free? Tax-exempt goods available for purchase on board, relevant for passenger services during flight.
E
- What is Echo? The letter 'E' as spoken in the ICAO phonetic alphabet, used to avoid miscommunication during ATC radio transmissions, e...
- What is Eight? The digit '8' as spoken in the ICAO radiotelephony alphabet, pronounced 'Eight' for clarity in all number transmissions ...
- What is electronic centralised aircraft monitor? An Airbus system that displays engine, system, and alert messages for aircraft monitoring and troubleshooting.
- What is Electronic Centralised Aircraft Monitoring Status? A system status or advisory displayed on the Electronic Centralised Aircraft Monitoring (ECAM) system, indicating real-t...
- What is electronic circuit breaker? A digitally controlled switch that protects an electrical circuit from overload by interrupting power supply electronica...
- What is Electronic Flight Bag Class One? A portable, non-mounted device (typically a commercial tablet or laptop) used for flight planning, charts, and manuals, ...
- What is Electronic Flight Bag Class Three? A permanently installed EFB system fully integrated with aircraft power and data, certified as part of aircraft avionics...
- What is Electronic Flight Bag Class Two? A portable EFB device that may be temporarily connected to aircraft power/data during flight but is stowed after use (FA...
- What is Electronic Flight Plan? A digitally filed and managed flight plan, submitted electronically to ATC, airlines, and relevant authorities, allowing...
- What is elevator power-control unit? A hydraulic actuator that converts hydraulic pressure into elevator movement, enabling pitch control of the aircraft.
- What is elevator-aileron computer? A dedicated computer on Airbus aircraft that processes inputs and controls elevator and aileron surfaces.
- What is ELT arming? The procedure of setting the emergency locator transmitter (ELT) to an armed state, ready to activate automatically upon...
- What is embedded cumulonimbus cloud? Cumulonimbus cloud obscured within other cloud layers, not visually identifiable, but with severe turbulence and precipi...
- What is Emergency descent? A rapid descent by an aircraft in response to an emergency situation.
- What is Emergency Descent? A rapid descent initiated by flight crew in response to a pressurization failure, smoke, or other onboard emergency.
- What is Emergency Descent Path? A predetermined safe vertical and lateral route for rapid descent to a lower altitude in the event of depressurization o...
- What is Emergency exit? Any aircraft door, hatch or window designated for passenger evacuation in an emergency situation.
- What is Emergency flashlight? Battery-powered flashlight mounted at crew station for use during evacuation or electrical failure.
- What is Emergency Locator Beacon? A portable beacon transmitting a distress signal for search and rescue, sometimes used interchangeably with ELT in aviat...
- What is Emergency locator transmitter? A radio beacon that transmits a distress signal to aid search and rescue teams in locating an aircraft in distress or af...
- What is Emergency Locator Transmitter? A radio beacon automatically activated to transmit a distress signal, assisting search and rescue in locating an aircraf...
- What is Emergency Medical Kit? Sealed on-board kit containing prescription drugs and advanced medical supplies, used in-flight by qualified personnel f...
- What is Emergency Water Pack? Sealed potable water container included in life-raft survival kit to supply drinking water for occupants in distress.
- What is Energy Management? Pilot technique balancing airspeed and altitude by trading potential and kinetic energy for efficient trajectory control...
- What is engine anti‑ice? A system that prevents or removes ice formation on engine inlets, typically using hot bleed air.
- What is Engine breakaway? Ground instruction for pilots to apply brief higher thrust to overcome static friction and initiate taxi from standstill...
- What is Engine Failure? A condition where one or more aircraft engines cease to provide thrust, requiring immediate emergency procedures.
- What is Engine feed? The process or system of supplying fuel from the tanks to an aircraft engine for combustion and operation.
- What is Engine Fire Extinguishing Bottle? A pressurized container installed in aircraft engines used to release extinguishing agent when a fire is detected.
- What is Engine Health Monitoring? Continuous or periodic analysis of engine data to assess performance, detect faults, and schedule maintenance (ICAO Doc ...
- What is Engine Indication and Crew Alerting System Message? A visual and/or aural alert generated by the Engine Indication and Crew Alerting System (EICAS or ECAM) to inform pilots...
- What is Engine Inoperative Drift? The lateral displacement from track or altitude lost when an aircraft operates with one or more engines inoperative, esp...
- What is engine instrument display? The cockpit display panel showing all vital engine parameters, including N1/N2, temperature, oil pressure, fuel flow, an...
- What is engine oil pressure? The pressure of oil circulating through an aircraft engine, essential for lubrication and cooling of moving components.
- What is engine pressure ratio? Ratio of total pressure at the engine exhaust to that at the engine inlet, used as a primary engine thrust indicator.
- What is Engine run area? A designated ground location where aircraft engines may be operated at power levels above idle for maintenance or operat...
- What is Engine Separation? A catastrophic in-flight event where the engine detaches from the aircraft structure, requiring immediate emergency hand...
- What is Engine start? The action of starting aircraft engines, typically following ATC clearance. Communicated between flight crew and ground ...
- What is engine-indication and crew-alerting system? A Boeing system that displays engine and system data and alerts for operational and abnormal conditions.
- What is Engineering order applied? Formal modification or repair directive implemented and documented by engineering, referenced in aircraft technical reco...
- What is Enhanced Vision System? Onboard system using infrared or millimeter wave cameras to improve pilot visibility of runway, terrain, and obstacles i...
- What is Entry Transition Point? The designated waypoint where an aircraft changes from domestic to oceanic or remote-airspace procedures and communicati...
- What is en‑route alternate fuel? Fuel required to fly from the destination to an alternate aerodrome en‑route under planned conditions.
- What is Equal Fuel Point? A point along the route where the fuel required to return to the departure airport equals the fuel required to continue ...
- What is Equal Time Chart? A chart used in flight planning to determine the point at which the flight time to two alternate aerodromes is equal, co...
- What is Equal Time Point? The geographic point along a route at which the flying time to two selected diversion aerodromes is equal, used for cont...
- What is Equal Time Point? A calculated position along the planned route where the time required to continue to a suitable alternate aerodrome is t...
- What is Equatorial Route? A specific flight route crossing or lying close to the equator, designed for optimal navigation in equatorial regions.
- What is equivalent airspeed? Indicated airspeed corrected for compressibility effects at altitude, used for performance comparisons.
- What is Escape Fuel Planning? Calculation of the minimum fuel required to depart from an area with operational hazards to a safe location.
- What is Escape Rope? Heavy-duty rope stowed above cockpit side windows, used for crew self-evacuation when slides unusable.
- What is Escape Route Planning? The advance definition of contingency flight paths from the main track to a safe diversion airport in case of in-flight ...
- What is Escape Slide Deployment? The act of activating and extending the inflatable escape slide on an aircraft to facilitate emergency evacuation.
- What is Escort? The authorized accompaniment of an aircraft, vehicle, or personnel by an assigned entity, usually for safety or security...
- What is Estimating? A term used by pilots to indicate the estimated time of arrival at a specific point.
- What is ETOPS Minimum Equipment List? The Minimum Equipment List applicable to extended-range (ETOPS) flights, specifying the minimum required equipment for o...
- What is European Geostationary Navigation Overlay Service? The European SBAS providing GNSS augmentation for safety-critical aviation operations, enabling APV and LPV approaches a...
- What is Evacuation command? A clear, standardized verbal instruction given by crew to passengers to initiate a rapid and orderly evacuation in an em...
- What is Evacuation slide inoperative? Inflatable escape slide at an aircraft door unserviceable, precluding passenger carriage until rectified or deferred per...
- What is exhaust gas temperature? The temperature of gases emitted by the engine exhaust, critical for monitoring engine health and performance.
- What is exit row? Row of seats adjacent to an emergency exit, where passengers have responsibilities for assisting in case of evacuation.
- What is Expect? Used by ATC to advise pilots of anticipated instructions or clearances, such as altitude changes or approach clearances,...
- What is Expect further clearance? An instruction indicating that further clearance will be provided at a specified time or location.
- What is Expect vectors? An advisory indicating that the pilot should anticipate receiving radar vector instructions from ATC at a specified time...
- What is Expedite? A phrase used to instruct the pilot to hasten a maneuver or action.
- What is explosive-charge squib? A small pyrotechnic device used to rapidly release fire-extinguishing agent by rupturing a fire bottle seal.
- What is Extended holdover? An officially authorized increase in the maximum allowable holdover time beyond standard tables, based on improved weath...
- What is Extended Overwater? Flight operation segment that takes place beyond a specified distance from land, requiring special equipment and regulat...
- What is Extended Range Limitation? A regulatory or operational constraint that restricts the maximum allowable distance or duration for extended range oper...
- What is Extended Range Operations? Flight by any aircraft on routes that place it at a distance from a suitable airport greater than the authorized thresho...
- What is Extended Twin Operations? Operation of twin-engine aircraft on routes where a diversion airport may be more than 60 minutes away at one-engine ino...
- What is Extended-range Twin-engine Operations Entry Point? The geographic position from which an aeroplane on an approved extended-range twin-engine operation (ETOPS) flight enter...
- What is Extra (contingency) fuel? The discretionary amount of fuel carried beyond required minimums to address potential delays, weather, or other unfores...
F
- What is Fail-Operational Autoland Mode? Autoland logic able to complete flare, touchdown and rollout after any single-component failure below alert height.
- What is Fail-Passive Autoland Mode? Autoland configuration where a single failure causes autopilot disengage but leaves aircraft in trim, allowing manual la...
- What is Fatigue Risk Management? A systematic approach by operators to monitor and manage crew fatigue risk, including procedures, training, and reportin...
- What is Fatigue Risk Management? A systematic process, approved by authorities, to manage crew fatigue using scheduling, monitoring, and mitigation strat...
- What is Ferry flight permission? Authority granted to reposition an aircraft without revenue passengers, often under MEL limitations, to maintenance or d...
- What is Fifth-Generation C-Band Connectivity? A communications system using 5G cellular technology in the C-band spectrum for high-speed, low-latency data transfer to...
- What is Final? The last leg of the approach path before landing.
- What is Final approach? The segment of an instrument approach procedure in which alignment and descent for landing are completed, extending from...
- What is Final Approach Fix? A designated point in an instrument approach from which the final approach segment to the runway begins.
- What is Final-approach speed? The target airspeed maintained by an aircraft during the last segment of the approach for landing, determined by aircraf...
- What is Fire Containment Bag? High-temperature-resistant bag used on board to isolate and contain lithium battery or PED fires until landing.
- What is Fire gloves? Specialized protective gloves provided to crew members for handling hot, burning, or smoldering objects during fire emer...
- What is Fire Warning? Automated alert indicating detection of fire or overheat in an aircraft system area, requiring immediate crew action.
- What is fire-detection loop? A continuous sensing circuit that detects overheat or fire in aircraft engines, APU, or cargo bays.
- What is fire-extinguisher bottle? A pressurized container storing extinguishing agent for aircraft fire suppression in engines, cargo, or APU compartments...
- What is First aid kit? A container holding medical supplies and equipment for treatment of minor injuries or illnesses during flight.
- What is First aid kit? Regulation medical supplies kit carried on board for treatment of minor injuries and illnesses.
- What is First Aid Kit? A collection of supplies and equipment for use in giving first aid in case of minor injuries or medical needs onboard.
- What is First fluid? The initial de-icing or anti-icing fluid applied to remove contaminants from aircraft surfaces, typically a heated mixtu...
- What is Fixed oxygen? A permanently installed aircraft oxygen supply system, providing breathable oxygen to designated cabin or cockpit outlet...
- What is fixed‑reserve fuel? Fixed quantity of fuel required to be carried for emergencies as per regulatory minimum reserve rules.
- What is flaperon? A combined flight control surface that functions as both aileron and flap, used on some aircraft to improve control and ...
- What is Flaps? Hinged surfaces on the trailing edge of the wing that can be extended to increase lift at lower speeds, used during take...
- What is Flare? Landing manoeuvre in which the pilot raises the nose to arrest the descent rate just before touchdown.
- What is Flashlight? A battery-powered portable light source provided to crew members to assist in emergency evacuations, inspections, or ope...
- What is Fleet campaign directive? Mandatory maintenance or modification order issued by the operator or manufacturer, applicable to an entire fleet.
- What is Flexible Assumed Temperature? Artificially higher temperature entered in FMS to calculate reduced-thrust take-off setting (flex) within performance li...
- What is Flight attendant restraint kit? A kit containing handcuffs, tape, and straps for restraining disruptive passengers in accordance with FAA or EASA proced...
- What is flight augmentation computer? A system on Airbus aircraft that provides additional functions such as yaw damping, rudder trim, and flight envelope pro...
- What is Flight Control Jam? A condition in which the aircraft's primary or secondary flight control surfaces become unresponsive or stuck due to mec...
- What is Flight crew defect report? Written logbook entry by flight crew describing observed technical defect or malfunction requiring maintenance action.
- What is Flight level? A standardised altitude expressed in hundreds of feet, based on a pressure setting of 1013.2 hPa.
- What is flight management system? An avionics system integrating navigation, performance, and flight planning for automated aircraft operation.
- What is Flight Management System? An integrated avionics system that automates flight planning, navigation, performance, and guidance calculations through...
- What is Flight Operations Quality Assurance? A program for analyzing digital flight data to identify, assess, and mitigate operational safety risks, supporting proac...
- What is Flight Path Vector? Symbol on HUD or PFD showing instantaneous trajectory of aircraft relative to horizon and runway aiming point.
- What is Flight Redispatch? The in-flight process whereby operational control re-evaluates conditions and issues a new release for the remainder of ...
- What is flight-control hydraulic circuit? Hydraulic circuit dedicated to supplying pressure to flight control surfaces such as ailerons, elevators, and rudder.
- What is Flight-Deck Wireless Fidelity Network? A secure Wi-Fi network within the cockpit for connecting Electronic Flight Bags, avionics, or crew devices, isolated fro...
- What is flight-director bars? Visual cues on the Primary Flight Display indicating desired pitch and roll to guide manual flight path.
- What is flight-warning computer? A system that processes and displays warnings and cautions to the flight crew in response to abnormal conditions.
- What is fly-by-wire? An electronic flight control system where pilot inputs are transmitted as electrical signals to computers, which command...
- What is FOD check? A visual and procedural inspection of airport movement areas, particularly runways, taxiways, and aprons, to identify an...
- What is Four? The ICAO/FAA radiotelephony spelling for the numeral '4'. Used to clearly communicate headings, altitudes, frequencies, ...
- What is Four-Dimensional Trajectory? A predicted or managed aircraft flight path defined by latitude, longitude, altitude, and time—core to Trajectory-Based ...
- What is Fourth-Generation Air-Ground Broadband? A broadband communication system using 4G/LTE technology to provide high-speed data links between aircraft and ground st...
- What is Foxtrot? The letter 'F' as spoken in the ICAO phonetic alphabet, used for taxiway designation, holding points, and callsign clari...
- What is Freezing Level? The lowest altitude in the atmosphere at which the air temperature drops to 0°C (32°F), marking the boundary where liqui...
- What is Frequency change approved? ATC clearance for the pilot to leave the current frequency, typically when no further communication is required on that ...
- What is Frost inspection? A mandatory check for frost, ice, or snow contamination on critical aircraft surfaces before departure to ensure safe fl...
- What is Fuel ageing? The process by which stored aviation fuel undergoes chemical changes over time, leading to potential deterioration of qu...
- What is Fuel contamination? Presence of water, biological growth, particulates or other foreign matter in aviation fuel that renders it unserviceabl...
- What is Fuel coupler? Mechanical fitting connecting hydrant hose to aircraft or fueling truck manifold.
- What is Fuel Crossfeed? A procedure that allows fuel to be transferred from one tank to another, typically to correct a fuel imbalance or supply...
- What is Fuel crossflow? The procedure or system of transferring fuel between tanks or sides of the aircraft to maintain balance or correct asymm...
- What is Fuel density? Measured mass per unit volume of fuel, expressed for aviation as kilograms per litre, used for accurate fuel weight calc...
- What is Fuel doping? The process of adding specific chemical additives to aviation fuel to improve its properties, such as preventing microbi...
- What is Fuel Emergency? A condition where an aircraft’s fuel state is such that without immediate landing, safe completion of flight is doubtful...
- What is Fuel filter? A device in the fuel system designed to remove contaminants from aviation fuel before it reaches the engine or fuel syst...
- What is Fuel freeze point? The lowest temperature at which aviation fuel can remain fluid. If fuel cools below this point, it begins to solidify an...
- What is Fuel hydrant? Fixed valve on apron infrastructure supplying pressurised fuel to hydrant carts or hoses.
- What is Fuel Hydrant? An underground fueling system point on the apron where aircraft can be refueled directly through a hydrant instead of fu...
- What is Fuel Imbalance? A condition in which there is a significant difference in the quantity of fuel between the left and right tanks, potenti...
- What is Fuel Imbalance Control? Actions taken to monitor and correct uneven fuel distribution between tanks to maintain safe balance and aircraft handli...
- What is Fuel leak? An unintentional escape of fuel from tanks, lines, or components, posing a safety and fire hazard requiring immediate no...
- What is Fuel Panel? An external aircraft access panel containing controls and connections for fuel loading operations, typically located und...
- What is Fuel receipt? Document provided by the fuel supplier showing quantity, density, time and place of fuel uplift, signed by the aircraft ...
- What is Fuel sampling? Procedure of drawing a representative fuel sample from tanks or hydrant points to check for water, particulates or other...
- What is Fuel scavenge? The operation of removing remaining fuel from tanks or lines, especially from areas not emptied by normal fuel pump oper...
- What is Fuel shear coupling? A safety device in fuel systems designed to disconnect or break under excessive force, preventing fuel spillage and syst...
- What is Fuel sump? A low point or reservoir in an aircraft fuel tank or system where water, debris, and contaminants collect and can be dra...
- What is Fuel tank entry? The procedure of authorized personnel physically entering an aircraft fuel tank for inspection, cleaning, or maintenance...
- What is Fuel Tanker Flight? A flight carrying more fuel than required, often to avoid higher fuel costs at destination or for operational contingenc...
- What is Fuel temperature? The measured temperature of aviation fuel within tanks, lines, or engines. Critical for preventing fuel freezing at alti...
- What is Fuel Temperature Limit? The minimum or maximum allowable temperature for fuel in aircraft tanks or lines to prevent fuel waxing or freezing, esp...
- What is Fuel Transfer? The movement of fuel between tanks to ensure aircraft balance and supply during various flight phases.
- What is Fuel uplift? Quantity of fuel added during a refuelling operation, expressed in kilograms, litres or pounds.
- What is Fuel vent? A device or opening that allows vapors and air to escape or enter aircraft fuel tanks to maintain pressure balance and p...
- What is full authority digital engine control? An electronic system that provides complete automated control of all engine parameters for optimum performance.
- What is Functional test needed? Indicates requirement for an operational or systems test to confirm correct function of a repaired or replaced item.
- What is Future Air Navigation System one-alpha? An ICAO standard for data link communications in oceanic and remote airspace; FANS 1/A enables CPDLC and ADS-C functions...
G
- What is Galley position? The specified location or compartment onboard the aircraft dedicated to the storage and preparation of food and beverage...
- What is Galley power? The electrical power supply dedicated to the aircraft galley, required for safe operation of galley equipment such as ov...
- What is Galley secure? A phrase indicating that all galley equipment, carts, and supplies are properly stowed and locked for safe taxi, takeoff...
- What is Galley waste bin? Fire-retardant container in the galley for collection of cabin refuse; equipped with self-closing lid.
- What is Gate? A designated area at an airport where passengers board or disembark from an aircraft.
- What is Gate change? A revision in the assigned boarding or arrival gate for an aircraft, typically communicated via airport operations or AT...
- What is Gate-checked bag? Oversize or excess carry-on item tagged at the boarding gate and stowed in the aircraft hold.
- What is GBAS Ground Station? A ground-based transmitter providing precision approach and landing guidance by augmenting GNSS signals for aircraft at ...
- What is GBAS Landing System? A precision approach and landing system using GNSS signals enhanced by a Ground-Based Augmentation System (GBAS), provid...
- What is Gear up? A cockpit command for retracting the landing gear, given after a positive rate of climb is established post-takeoff.
- What is generator control unit? Electronic module that manages and protects an aircraft generator, monitoring voltage, current, and system faults.
- What is Girt bar? Metal bar at the base of the slide pack that secures the slide to the aircraft floor when armed or disengages it when di...
- What is Glide slope? The vertical guidance portion of an ILS, providing an optimal descent path to the runway threshold for precision approac...
- What is Glide Slope? The vertical guidance component of an Instrument Landing System (ILS) that provides the optimal descent path to the runw...
- What is global navigation satellite system? A system of satellites providing worldwide navigation, including GPS, GLONASS, Galileo, and BeiDou.
- What is Global Navigation Satellite System Interference? Any deliberate or accidental disruption of GNSS signals affecting navigation and surveillance for aircraft, including ja...
- What is Global Navigation Satellite System Spoofing? A deliberate electronic attack that manipulates GNSS signals to provide false position or timing data to aircraft, endan...
- What is Global Positioning System? A satellite-based navigation system providing accurate position, velocity, and time information to aircraft and other us...
- What is Glycol recovery? The process of collecting used glycol-based de-icing or anti-icing fluids from airport surfaces after application for en...
- What is Go around? An aborted landing approach, requiring the aircraft to climb and reattempt landing.
- What is Go-around altitude? The published altitude to which an aircraft must climb when executing a missed approach or go-around procedure.
- What is Golf? The letter 'G' as spoken in the ICAO phonetic alphabet, used for clear identification of taxiways, holding points, or ai...
- What is GPS Approach? An instrument approach procedure that uses signals from the Global Positioning System (GPS) for navigation and guidance ...
- What is GPU connected? Confirmation that the Ground Power Unit is attached and supplying external electrical power to the aircraft while on the...
- What is green hydraulic system? One of three independent hydraulic systems on Airbus aircraft, powering primary flight controls, landing gear, and other...
- What is Grid Navigation? A navigation technique using a grid reference system rather than true or magnetic north, primarily in polar regions wher...
- What is Ground handling? All services required by an aircraft between landing and take-off, excluding air traffic control services. This includes...
- What is Ground power unit? A mobile or fixed unit that supplies electrical power to an aircraft on the ground when the engines or APU are not runni...
- What is ground proximity warning system? An aircraft safety system that warns pilots if the aircraft is at risk of controlled flight into terrain or obstacles.
- What is Ground Proximity Warning System? An onboard system that alerts pilots if the aircraft is in immediate danger of flying into the ground or an obstacle.
- What is Ground speed? The speed of an aircraft relative to the surface of the Earth, as measured by navigation systems.
- What is ground spoilers? Spoiler panels on the wings that fully deploy upon landing to disrupt lift and aid in braking and deceleration.
- What is Ground Time? The total duration an aircraft spends on the ground between landing and takeoff, including taxiing, servicing, and board...
- What is Ground time indicator? A device or system that records or displays the elapsed time an aircraft spends on the ground between arrival and depart...
- What is Ground-Based Augmentation System? A system that enhances the accuracy, integrity, and availability of GNSS signals for aviation by providing local ground-...
- What is ground‑roll distance? The distance from brake-release or acceleration point to airplane lift-off during take‑off roll.
- What is gust? A sudden, brief increase in wind speed, typically varying with rapid fluctuations.
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- What is Halon extinguisher? A fire extinguisher charged with halon gas, used for rapid suppression of onboard electrical and flammable liquid fires.
- What is Halon fire extinguisher? Hand-held extinguisher charged with Halon 1211/1301 for cabin or flight-deck Class B/C fires.
- What is Harness? A system of webbing straps used to secure a flight crew member, typically including shoulder and lap belts, to their sea...
- What is Head count? A manual verification by cabin crew of the total number of passengers and crew on board, used to confirm the manifest an...
- What is Head-Up Display? Transparent cockpit display showing critical flight data within the pilot’s forward field of view, reducing the need to ...
- What is Head-wind component? The part of the wind velocity that blows directly against the direction of travel of the aircraft, improving takeoff and...
- What is Heading? The direction in which the aircraft’s nose is pointed, expressed in degrees from magnetic north.
- What is Heading? The direction in which an aircraft’s nose is pointed, expressed in degrees from North. May differ from track due to wind...
- What is head‑wind component? The component of the wind along the runway axis directed opposite to aircraft’s travel, used for performance calculation...
- What is Heaving Line? Light rope fitted with weighted end carried in life-rafts to establish first connection with rescue vessel.
- What is High Frequency Calling? The use of HF radio to establish long-distance communications with ATC, commonly required in remote or oceanic airspace.
- What is High Latitude Navigation? Navigation procedures and technologies required for flights operating in polar or near-polar regions, often above 78° la...
- What is High Pressure? An area of the atmosphere where the pressure is higher than that of the surrounding region, often associated with stable...
- What is High-Frequency Data Link? A long-range communication system enabling digital message exchange between aircraft and ground stations via high-freque...
- What is high-frequency radio? Radio system operating in the HF band (3–30 MHz), enabling long-distance voice communication between aircraft and ATC.
- What is High-lift loader? A high-lift ground support equipment used to load and unload Unit Load Devices (ULDs) or pallets into aircraft cargo hol...
- What is high-pressure rotor speed? Rotational speed of the high-pressure compressor or core in a jet engine, commonly indicated as N₂.
- What is High-Throughput Satellite? A new generation of satellite technology providing much greater data capacity and bandwidth to aircraft for broadband co...
- What is Hijacking? The unlawful seizure of an aircraft by an individual or group, often involving threats or force, during any phase of fli...
- What is Hold? To maintain a specific position or altitude, often in a holding pattern.
- What is Hold at? An instruction to maintain a specific position or altitude until further notice.
- What is Hold line? A clearly marked line on the surface of an aerodrome, usually at a runway/taxiway intersection, beyond which an aircraft...
- What is Hold pattern? A predetermined maneuver which keeps an aircraft within a specified airspace while awaiting further clearance, typically...
- What is Hold short? An instruction to stop before reaching a specified point, usually a runway or intersection, and not proceed until furthe...
- What is Holding Entry? The initial maneuver by which an aircraft enters a holding pattern as prescribed, using one of the approved entry proced...
- What is Holding Fix? A specified point, identified by navigation aids or coordinates, at which an aircraft may be instructed to hold.
- What is Holding fuel? The quantity of fuel specifically reserved for holding patterns in case of delays before approach or landing.
- What is Holding pattern? A racetrack-shaped flight path flown to delay an aircraft's approach.
- What is Holdover time? The estimated time anti-icing or de-icing fluid will prevent formation of frost, ice, or snow on the aircraft's critical...
- What is hold‑over time? Estimated time fluid will prevent ice before need for re‑application.
- What is Horizontal Situation Indicator? A cockpit instrument that displays aircraft position relative to navigation aids and selected course, combining heading ...
- What is Hot drinks? Beverages such as tea, coffee, or hot water, served by cabin crew. Handling and service must comply with safety procedur...
- What is Hot nozzle? A component of ground de-icing equipment that delivers heated anti-icing or de-icing fluid under pressure for effective ...
- What is Hotel? The letter 'H' as spoken in the ICAO phonetic alphabet, used to identify taxiways, holding points, or callsigns in ATC c...
- What is Hundred? The ICAO/FAA standard radiotelephony word for the figure '100' when transmitting altitudes, flight levels, and headings ...
- What is hydraulic accumulator? A pressurized storage device that maintains hydraulic pressure and absorbs system shocks.
- What is Hydraulic Overheat? A condition in which the aircraft hydraulic system exceeds its normal operating temperature limits, potentially leading ...
- What is Hydraulic Pressure Loss? A reduction or complete loss of hydraulic system pressure, potentially affecting flight control surfaces, landing gear, ...
- What is hydraulic pump? A device that moves hydraulic fluid under pressure to operate aircraft systems such as landing gear, brakes, and flight ...
- What is Hydraulic Quantity Low? Indicates that the fluid level in a hydraulic reservoir is below the specified minimum for safe system operation.
- What is hydraulic reservoir? A tank storing hydraulic fluid for aircraft hydraulic systems, ensuring continuous supply during all phases of operation...
- What is Hydraulic System Failure? A malfunction in the aircraft's hydraulic system, potentially affecting control surfaces, landing gear, or brakes.
- What is Hypothermia blanket? A thermal or space blanket included in survival kits to prevent loss of body heat and treat hypothermia in survivors exp...
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- What is Ice Crystal Icing? A form of high-altitude icing caused by ingestion of ice crystals into engines, potentially resulting in engine flameout...
- What is Icing? The accumulation of ice on aircraft surfaces due to supercooled water droplets, which can affect aerodynamics and instru...
- What is Ident? A function on the aircraft transponder that, when activated, causes the radar return to flash on the controller’s screen...
- What is Idle descent? A descent procedure where engines are set to idle thrust, allowing the aircraft to descend primarily due to gravity, opt...
- What is Idle reverse thrust? Minimum reverse-thrust setting used during rollout to aid deceleration while reducing noise, FOD risk, and brake wear.
- What is In-flight Engine Start? The procedure of starting an engine during flight, often due to engine flameout or following maintenance.
- What is In-flight entertainment system? A dedicated electronic system installed in the aircraft cabin, delivering audio, video, and interactive entertainment co...
- What is In-Flight Ice Accretion? The buildup of ice on aircraft surfaces during flight due to supercooled water droplets freezing on contact, which can i...
- What is Inadmissible? A passenger who is not permitted entry to a country by authorities and must be returned to the point of origin or anothe...
- What is Inbound Leg? The segment of a holding pattern or approach procedure flown toward the fix or navigation aid, typically timed or distan...
- What is Increase speed? A phrase used to instruct the pilot to increase the aircraft's speed.
- What is India? The letter 'I' as spoken in the ICAO phonetic alphabet, used in ATC communications for identifying taxiways, holding poi...
- What is India? The letter 'I' as spoken in the ICAO phonetic alphabet, used in ATC for identifying taxiways, holding points, and aircra...
- What is Indicated airspeed? The airspeed value read directly from the aircraft’s airspeed indicator, not corrected for instrument or atmospheric err...
- What is inertial navigation system? A self-contained navigation system using accelerometers and gyros to compute aircraft position, independent of external ...
- What is Inertial Navigation System? A self-contained navigation system that determines aircraft position and velocity by processing accelerations and rotati...
- What is Inertial Reference System? A subsystem of an INS providing attitude, position, and velocity reference information for aircraft systems and crew.
- What is inertial reference unit? An aircraft system providing position and attitude data by processing gyroscopic and accelerometer inputs.
- What is Infant belt? Supplementary loop belt that attaches an infant to an adult’s seat belt during taxi, take-off, landing and turbulence.
- What is Infant Life Vest? Life-jacket sized for infants under 18 kg, equipped with head support, light and tether for water evacuation.
- What is Infant seat belt? Supplementary loop belt attached to adult lap belt to secure an infant on a guardian’s lap during flight.
- What is Inflight Replanning? Modification of the flight plan while airborne, in response to operational, weather, or airspace constraints.
- What is inflight service? Services provided to passengers during flight, such as meals and beverages, potentially affecting departure or operation...
- What is Initial approach? The segment of an instrument approach procedure between the initial approach fix and the intermediate or final approach ...
- What is Initial Approach Fix? A designated point where an aircraft initiates the instrument approach procedure for a specific approach segment, leadin...
- What is Initial Four-Dimensional Trajectory? The first shared, predicted trajectory of an aircraft, including latitude, longitude, altitude, and time, used in Trajec...
- What is Inspection due soon? Notification that a scheduled inspection interval will be reached within a short time frame, requiring planning.
- What is Instrument? A term used to describe operations conducted with reference to instruments.
- What is instrument landing system? A precision approach system providing lateral and vertical guidance to aircraft during landing using radio signals.
- What is Instrument Landing System? Precision approach aid providing lateral (localizer) and vertical (glide slope) guidance to a runway.
- What is Instrument Landing System Category II Approach? Precision approach using ILS equipment with decision height not lower than 100 ft and RVR not less than 300 m.
- What is Instrument Landing System Category IIIA Approach? ILS precision approach with decision height below 100 ft and RVR not less than 200 m; autopilot or HUD guidance required...
- What is Instrument Landing System Category IIIB Approach? ILS precision autoland with no decision height or below 50 ft and RVR as low as 75 m, requiring fail-operational capabil...
- What is Intake Hazard? The danger posed by the suction force of a running jet engine's intake, which can pull in objects or personnel nearby.
- What is integrated drive generator? A generator that converts variable engine speed to constant frequency AC power for aircraft electrical systems.
- What is Intercept? A maneuver where an aircraft joins a specified course, radial, localizer, track, or route as instructed by ATC, commonly...
- What is Interim Procedural Revision? A temporary update to operational or maintenance procedures, issued before the next official revision, to address urgent...
- What is Intermediate fix? A designated point on an instrument approach procedure (IAP) between the initial and final approach fixes, used to defin...
- What is International Standard Atmosphere? A model of the atmosphere based on standard average conditions at sea level, used for calibrating instruments and perfor...
- What is International Standard Atmosphere Deviation? The difference between the actual atmospheric temperature and the standard temperature defined by the International Stan...
- What is Interphone inoperative? Internal crew communication system not functioning, affecting cockpit-cabin coordination and triggering MEL action.
- What is Intersection? A point defined by the crossing of two or more airways, radials, or routes, used as a reference for navigation or report...
- What is Island Alternate? An aerodrome located on an island and designated as an alternate for oceanic or remote area operations.
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- What is Jet Blast? The high-speed exhaust from a jet engine, which can cause damage or injury if encountered by personnel or equipment.
- What is Jet bridge? An enclosed, movable connector that extends from the airport terminal gate to an aircraft door for passenger boarding an...
- What is Jet Route? A designated airway in controlled airspace, typically for aircraft operating at high altitudes (usually above FL180 in t...
- What is jet stream? A narrow, fast-flowing air current in the upper atmosphere, typically between 20 000 and 50 000 ft, affecting cruise per...
- What is Jet Stream Core? The center of maximum wind velocity within a jet stream, critical for optimizing flight path, fuel efficiency, and turbu...
- What is Join? Instruction to intercept and follow a specified route, airway, arrival procedure, or traffic pattern.
- What is Join airway? An instruction to enter and follow a designated airway.
- What is Join base? Instruction to enter the circuit on the base leg, a perpendicular segment to final approach before landing.
- What is Join downwind? An instruction to enter the traffic circuit on the downwind leg, parallel to and opposite direction of landing runway.
- What is Join final? An instruction to align the aircraft with the final approach path for landing.
- What is Juliett? The letter 'J' as spoken in the ICAO phonetic alphabet, used in ATC to designate taxiways, holding points, or aircraft i...
- What is Jumpseat? A foldable seat located in the cockpit or cabin, reserved for off-duty crew, training personnel, or authorized observers...
- What is Jumpseat authority? Permission granted by the operator or authority for a non-operating crew member to occupy a jumpseat in the cockpit or c...
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- What is L-Band Satellite Communications? Satellite-based communication for aircraft using L-band frequencies (1–2 GHz), supporting global voice and data links (I...
- What is Landing Alternate? An aerodrome specified in the flight plan to which a flight may proceed when a landing at the intended destination becom...
- What is Landing distance available? Declared length of runway that is available and suitable for the ground run of an aircraft landing.
- What is Landing distance required? Calculated distance an aircraft needs to land and come to a complete stop under existing conditions.
- What is Landing Gear Door Open? A situation where the landing gear doors remain open after gear extension or retraction, indicating a potential malfunct...
- What is Landing gear down? The position and status indicating the aircraft’s landing gear is fully extended and locked for touchdown and ground ope...
- What is Landing Gear Malfunction? A failure in the aircraft's landing gear system preventing proper extension or retraction.
- What is Landing System Status? Cockpit annunciation indicating availability and health of localizer, glide-slope and autoland monitoring channels.
- What is LASER Waypoint? A specifically named waypoint (LASER) used in navigation or published procedures, commonly appearing in STARs, SIDs, or ...
- What is Lateral Navigation? A component of navigation relating to the aircraft's position in the horizontal plane (track), including guidance along ...
- What is Lateral Navigation and Vertical Navigation? A navigation mode providing both horizontal (lateral) and vertical guidance to the aircraft, commonly used in RNAV and R...
- What is Latitude and Longitude Coordinates? A geographic position expressed in degrees, minutes, and seconds or decimal degrees, specifying a point north or south o...
- What is Lav service? Ground service involving the emptying, cleaning, and replenishing of aircraft lavatory systems.
- What is Lavatory occupied light? Illuminated indicator showing lavatory in-use status to cabin crew and passengers.
- What is lavatory serviceable? Confirmation that the aircraft's lavatory system is fully operational and available for use during flight.
- What is Lavatory smoke? The detection or presence of smoke within an aircraft lavatory, indicating a possible fire hazard and requiring immediat...
- What is Lavatory smoke alarm? Detector-triggered alert indicating presence of smoke or vapour in aircraft lavatory.
- What is Lavatory Smoke Detection? An alert triggered by smoke sensors in the aircraft lavatory indicating possible fire, requiring immediate cabin crew an...
- What is Lavatory vacuum system? Indicates the operational status of the vacuum system in aircraft lavatories, essential for the proper flushing and sani...
- What is Layover? A scheduled break in a flight crew's duty period, typically involving an overnight stay at a destination before resuming...
- What is Leading-edge device? A movable aerodynamic surface, such as a slat or Krueger flap, installed on the wing’s leading edge and extended to incr...
- What is Leave airway? An instruction to exit a designated airway.
- What is Leaving? Used by pilots to report they are vacating a specific altitude, either climbing or descending from it.
- What is Level? A generic term used to denote a pilot's cleared vertical position, whether expressed as an altitude, flight level, or he...
- What is Life Line? Webbing strap secured to over-wing exits, providing hand-hold for passengers evacuating onto wing during ditching.
- What is Life Raft Use? The procedure of deploying and utilizing inflatable life rafts by crew and passengers following a water landing, in acco...
- What is Life vest? Personal flotation device provided to each occupant for use during water ditching or sea evacuation.
- What is Life vest location? Designated stowage point of each passenger life jacket, usually beneath seat or in central console.
- What is Life vest missing? Required passenger flotation device absent from its assigned seat location, rendering that position unserviceable until ...
- What is Lightning Strike? A direct or indirect electrical discharge from the atmosphere to an aircraft, potentially causing damage to avionics, su...
- What is Lima? The letter 'L' as spoken in the ICAO phonetic alphabet, used in ATC communications for taxiway, holding point, or aircra...
- What is Line Operations Safety Audit? An observational safety program in which trained auditors monitor routine flight operations to identify threats and erro...
- What is Line up and wait? An air traffic control instruction for an aircraft to taxi onto the runway and hold in position, awaiting takeoff cleara...
- What is Line‑up? An ATC instruction for an aircraft to enter the runway and position itself for take-off, without commencing the take-off...
- What is Load control? Airline or ground-handling department responsible for planning, monitoring and approving aircraft loads, weight and bala...
- What is Load sheet? Official weight-and-balance document detailing masses, fuel, distribution and calculated centre of gravity for a specifi...
- What is Localizer? The horizontal guidance component of the ILS, providing lateral alignment with the runway centerline during instrument a...
- What is Localizer? The component of an Instrument Landing System (ILS) that provides lateral guidance to align the aircraft with the runway...
- What is Localizer Performance with Vertical Guidance? An instrument approach procedure (APV) that provides both lateral and vertical guidance using satellite-based augmentati...
- What is logbook entry? A formal record in the aircraft technical log documenting the status, action, or deferral of an MEL/CDL item for legal a...
- What is Long Range Cruise? A cruise speed selected for maximum range per unit of fuel on long-haul flights, balancing fuel efficiency and time.
- What is Loss Of Pressurization? A condition in which an aircraft's cabin fails to maintain the required pressure differential compared to the outside at...
- What is Lost and found? The official service or location at an airport or on board where lost property is reported and returned to passengers or...
- What is Lost property? Items belonging to passengers or crew that have been misplaced or left behind on the aircraft or in airport premises.
- What is Low approach? An approach over the runway where the aircraft descends to runway level but does not land, typically followed by a climb...
- What is Low Fuel State? A condition where the fuel remaining is less than planned final reserve but not yet an emergency.
- What is Low Pressure? An area of the atmosphere where the pressure is lower than that of the surrounding region, often associated with unsettl...
- What is Low Visibility Procedures? Aerodrome ground-movement and approach rules activated whenever reported runway visual range falls below published minim...
- What is low-pressure rotor speed? Rotational speed of the low-pressure compressor or fan in a jet engine, often indicated as N₁.
- What is Low-Speed Rejected Take-Off? A rejected take-off initiated at a speed below V1 due to abnormal indications, system failure, or runway hazard (ICAO Do...
- What is Low-visibility operations? Procedures and requirements for aircraft movements at aerodromes when visibility is reduced below specified minima, incl...
- What is Lower lobes? The compartments in the lower fuselage of an aircraft, often used for cargo or, on some aircraft, additional fuel storag...
- What is low‑level wind shear? Wind shear occurring below 2 000 ft AGL, especially hazardous during takeoff and landing phases.
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- What is Mach number? The ratio of the true airspeed of an aircraft to the speed of sound under the same atmospheric conditions. Used in ATC f...
- What is mach-trim system? A system that compensates for Mach tuck by automatically adjusting stabilizer trim at high subsonic speeds.
- What is Magazine rack? Dedicated stowage for in-flight magazines, often at galley or bulkhead area.
- What is Magnetic Course? The direction of flight over the ground with respect to magnetic north, obtained by correcting true course for magnetic ...
- What is Magnetic Variation? The angular difference between true north and magnetic north at a specific location. Used to calculate magnetic headings...
- What is Maintain? An instruction to continue holding a specified altitude, heading, speed, or other parameter until further advised.
- What is Maintain current altitude? Instruction to the pilot to continue flying at the present assigned altitude.
- What is Maintain IFR? A phrase used to instruct the pilot to continue flying under Instrument Flight Rules.
- What is Maintain own separation? A phrase used to instruct the pilot to ensure a safe distance from other aircraft without ATC assistance.
- What is Maintain runway heading? An instruction to continue on the magnetic heading of the runway after takeoff without turning, usually for departure se...
- What is Maintain VFR? A phrase used to instruct the pilot to continue flying under Visual Flight Rules.
- What is Maintain visual separation? A phrase used to instruct the pilot to visually keep a safe distance from other aircraft.
- What is Maintenance check flight? Post-maintenance air test conducted to verify aircraft performance and systems before return to commercial service.
- What is Maintenance control center? Centralized department overseeing aircraft technical status, defect clearance, and authorizing maintenance actions and M...
- What is maintenance procedure? A required action by maintenance personnel to address an MEL/CDL item, often prerequisite for dispatch or rectification.
- What is Manual braking? The act of the flight crew applying the aircraft's wheel brakes by hand or foot, rather than using automatic braking sys...
- What is Manual Inflation Handle? Red-coloured T-handle fitted to an escape slide or life-raft. Pulling it opens the gas cylinder to inflate the raft manu...
- What is Manual inflation handle? Lever or tab used by passenger to manually inflate life vest after evacuation into water.
- What is Manual Landing Gear Extension? The deployment of the aircraft's landing gear using a non-powered, manual backup system in the event of hydraulic or ele...
- What is Manual Position Report? A position report provided by a flight crew via voice or datalink, specifying current aircraft location, when automatic ...
- What is Manual Release Tool? Hand-held lever used to mechanically disengage an escape slide or raft from the aircraft door during evacuation or maint...
- What is Marker Beacon? A radio transmitter used in the ILS to provide pilots with range information along the approach path, typically located ...
- What is Marshall? A person responsible for providing visual signals to guide aircraft during parking, pushback, or maneuvering on the apro...
- What is master caution system? A central alerting system that warns the flight crew of abnormal but non-critical system status via lights and aural ton...
- What is Maximum Brake-Energy Speed? The highest speed from which an aircraft can stop without exceeding the maximum brake energy limit, used to ensure brake...
- What is maximum demonstrated cross-wind? The highest crosswind component at which satisfactory control was demonstrated during aircraft certification flight test...
- What is Maximum Tyre Speed? The highest ground speed a tire can sustain without risking structural failure, defined by aircraft and tire manufacture...
- What is Mayday? A distress call indicating a life-threatening emergency requiring immediate assistance.
- What is Mayday? International radiotelephony distress signal used to indicate a grave and imminent threat requiring immediate assistance...
- What is mean sea level? An altitude or elevation reference based on the average sea level used as a standard for aviation altimetry.
- What is Medical Emergency? A critical health-related situation on board requiring immediate attention and possible diversion to the nearest suitabl...
- What is Megaphone? A battery-powered portable loudspeaker used by crew to issue commands and instructions during evacuation or inoperative ...
- What is Memory Items? A set of critical procedures that flight crew must perform from memory during certain emergencies without consulting che...
- What is Merge-Point Sequencing? A terminal arrival procedure in which aircraft from different routes are directed to a predefined merge point and sequen...
- What is Meteorological Aerodrome Report? Routine coded weather observation for a specific aerodrome at a specific time.
- What is microburst? A small, intense downdraft producing damaging winds near the ground, hazardous to aircraft during takeoff or landing.
- What is Mike? The letter 'M' as spoken in the ICAO phonetic alphabet, used in ATC communications to designate taxiways, holding points...
- What is Minimum clean speed? The lowest speed at which an aircraft can fly in a clean configuration without deploying flaps or slats.
- What is minimum equipment? The essential items that must be serviceable for an aircraft to be dispatched under the MEL; if not available, flight is...
- What is minimum equipment list? An official list of equipment required for safe operation of an aircraft, specifying items which may be inoperative unde...
- What is Minimum Equipment List? An approved document listing the minimum equipment required for safe operation of an aircraft, permitting specified inop...
- What is Minimum Equipment List Relief? The operational allowance permitting dispatch or continued operation of an aircraft with certain inoperative items, as l...
- What is Minimum fuel? A declaration by a pilot indicating that the aircraft has enough fuel to reach the destination but no extra fuel for del...
- What is Minimum Fuel? A state where an aircraft’s fuel supply has reached minimum landing level; any additional delay may lead to emergency.
- What is Minimum turn? The shortest permissible time required for an aircraft turnaround, defined by airline procedures and airport resources t...
- What is Missed approach? A procedure followed when a landing cannot be completed.
- What is Missed approach? A published procedure to be followed when an instrument approach cannot be completed to a landing due to loss of require...
- What is Missed Approach Point? A specified point in an instrument approach procedure at which a missed approach must be initiated if the required visua...
- What is mixed icing? Presence of both rime and clear ice types on aircraft surfaces.
- What is mixing unit? A component that blends recirculated cabin air with conditioned air from the packs before distribution.
- What is Mode Control Panel? The autopilot interface panel allowing pilots to select, arm, or adjust flight modes such as heading, altitude, and vert...
- What is mode S transponder? An aircraft transponder providing selective, data-rich responses to ATC interrogations, supporting identification and su...
- What is moderate turbulence? Turbulence that causes changes in altitude and/or attitude but aircraft remains in control; occupants may feel strain ag...
- What is Monitor? Listen on a frequency without establishing two-way communication, maintaining awareness of transmissions
- What is Montevideo Alternate? Carrasco International (SUMU/Montevideo), designated as the alternate aerodrome for flights operating to/from South Atla...
- What is Mountain Wave? A standing atmospheric wave created when stable air flows over a mountain or ridge, often causing turbulence and rotor c...
- What is Multi-functional Satellite Augmentation System? Japan’s Satellite-Based Augmentation System providing GNSS augmentation for aviation, enabling precision approaches at a...
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- What is navigation display? Electronic display showing route, waypoints, navigation aids, weather, and traffic information.
- What is Navigation Display? An electronic cockpit display providing pilots with route, waypoint, weather radar, and traffic information to support f...
- What is Navigation Fix? A specific geographical position determined by visual reference, radio aid, or satellite, used in defining air routes, p...
- What is Negative? A standard radiotelephony term meaning 'No'; used to indicate a negative response or denial.
- What is Negative contact? Phrase used by pilots to indicate that they do not have visual contact with the reported traffic.
- What is Next Generation Air Transportation System? The United States’ initiative (NextGen) to modernize the national airspace system, integrating new technologies, automat...
- What is Next Waypoint? The upcoming predefined navigation fix along a flight route, as programmed in the flight management system and used for ...
- What is Nitrogen generation? The production of nitrogen gas, typically onboard, for use in fuel tank inerting systems to prevent combustion.
- What is No smoking? A mandatory cabin safety instruction indicating that smoking is prohibited on board the aircraft.
- What is no-go item? An inoperative or missing item which, according to MEL or regulatory requirements, prevents the aircraft from being lega...
- What is non-directional beacon? A ground-based radio transmitter used for navigation, providing direction by reference only.
- What is Non-Directional Beacon? Low-frequency radio beacon transmitting a non-directional signal that pilots track with an ADF receiver.
- What is Non-Normal Checklist? A predefined checklist used by pilots to address abnormal but not emergency situations.
- What is Non-routine Work Entry? A maintenance log entry documenting unscheduled or unexpected technical issues or discrepancies detected during aircraft...
- What is non-service animal? An animal on board not trained to assist a person with a disability, such as a pet, requiring specific handling.
- What is nonessential equipment and furnishings? Equipment or furnishings that are not essential for the airworthiness or safety of the flight and may be deferred.
- What is Nonessential Equipment and Furnishings? Equipment and furnishings that are not required for safe operation or regulatory compliance and may be inoperative witho...
- What is North Atlantic Track? A designated system of daily updated routes for transatlantic flights between Europe and North America, coordinated and ...
- What is North Atlantic Track? A published daily route system over the North Atlantic, providing organized and coordinated tracks for transatlantic fli...
- What is North Pacific Track? A designated organized track system for flight operations across the North Pacific between North America and Asia, updat...
- What is nose-gear steering? The system that allows pilots to steer the aircraft’s nose landing gear during taxi and ground operations.
- What is November? The letter 'N' as spoken in the ICAO phonetic alphabet, used in ATC communications for taxiway and holding point identif...
- What is Nozzle pressure? The pressure at which de-icing or anti-icing fluid is delivered through equipment nozzles, affecting spray coverage and ...
- What is No‑spray zone? A designated aircraft area that must not be sprayed with de-icing or anti-icing fluid due to the presence of sensitive e...
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- What is Occluded Front? A composite weather front formed during the process of cyclogenesis when a cold front overtakes a warm front, leading to...
- What is Oceanic Clearance? ATC authorization required for entry into and flight within oceanic airspace, specifying route, level, and Mach number.
- What is Oceanic Entry Point? The specific waypoint where an aircraft transitions from domestic to oceanic airspace, usually involving a procedural cl...
- What is Oceanic Track? A published route across oceanic airspace, usually coordinated daily, which enables safe and efficient passage of aircra...
- What is Offset? A lateral deviation from a published route, airway, or track, authorized by ATC to avoid weather, traffic, or other haza...
- What is Oil Temperature Margin? The difference between actual engine oil temperature and the maximum safe operating limit, ensuring safe operation and i...
- What is On-time performance? A metric reflecting the punctuality of flights, indicating whether aircraft departures or arrivals occurred at the sched...
- What is One? The digit '1' as spoken in the ICAO radiotelephony alphabet, pronounced as 'One' for clarity in all numerical transmissi...
- What is operating empty weight? The weight of an aircraft including all standard items and operating fluids but excluding payload and usable fuel.
- What is Operating Minimums? The lowest meteorological and operational conditions under which an aircraft may be operated, as published by regulatory...
- What is Operational impact note? Written record in technical log noting operational effects or limitations resulting from an aircraft defect, MEL, or def...
- What is operational procedure? A mandatory action or set of actions required by flight crew to safely operate an aircraft system, especially with an ME...
- What is Operator Minimum Equipment List? The MEL approved by the state of the operator, tailored to specific airline operations, listing minimum equipment requir...
- What is Optimum Altitude? The flight level or altitude that offers the best balance between fuel consumption, aircraft performance, and weather co...
- What is Option? An ATC clearance that permits the pilot to perform a touch and go, stop and go, low approach, or full stop landing at th...
- What is ORA Waypoint? A published, named navigation point (ORA) used in RNAV procedures, typically representing a specific fix for routing, en...
- What is Orbit? A 360-degree turn in the air to delay or maintain position.
- What is Oscar? The letter 'O' as spoken in the ICAO phonetic alphabet, used in ATC communication for the identification of taxiways, ho...
- What is Out-of-phase check? Maintenance inspection not aligned with normal cycle, scheduled according to special interval or condition.
- What is Outbound Leg? The segment of a holding pattern or procedure flown away from the holding fix or navigation aid, typically timed or dist...
- What is outflow valve? A valve that regulates the discharge of air from the pressurized cabin to maintain desired cabin pressure.
- What is outside air temperature? The temperature of the air outside the aircraft, used in performance and anti-ice calculations.
- What is Oven circuit? The dedicated electrical circuit that supplies power to ovens in the aircraft galley. Its status is monitored for operat...
- What is Over-Wing Exit Use? The operation of over-wing emergency exits by passengers or crew during evacuation procedures, usually in the case of la...
- What is Over-wing fueling? Refueling conducted from a hose and nozzle inserted into the over-wing filler port.
- What is Overhead? A visual maneuver used to enter the traffic pattern from above the airfield, typically involving an initial pass over th...
- What is Overhead bin? A secure storage compartment above passenger seats used to stow carry-on baggage in the aircraft cabin.
- What is Overwing exit? Type-III emergency exit situated above the wing, used by able-bodied passengers to evacuate directly onto the wing surfa...
- What is Oxygen bottle? A portable or fixed cylinder of pressurized oxygen for supplemental breathing in decompression, smoke, or medical events...
- What is Oxygen drop-out? Automatic deployment of oxygen masks to passengers and crew in the event of a sudden loss of cabin pressure.
- What is Oxygen mask deployment? Automatic or manual release of supplemental oxygen masks from the passenger service unit during cabin depressurisation.
P
- What is pack valve? A valve that regulates the flow of bleed air into the air conditioning pack.
- What is packs? Air conditioning and pressurization units that cool, condition, and regulate the flow of air into the cabin using bleed ...
- What is Pan pan? A radio call indicating an urgent situation that is not immediately life-threatening.
- What is Pan-Pan? International urgency signal indicating a situation requiring assistance but not immediately life-threatening.
- What is Papa? The letter 'P' as spoken in the ICAO phonetic alphabet, used in ATC phraseology for the clear identification of taxiways...
- What is Parallel Entry? A method of entering a holding pattern where the aircraft initially flies outbound parallel to the holding course, then ...
- What is Parallel Offset? A specific type of offset in which the aircraft flies a route parallel to the original track, usually by a set number of...
- What is Parking? The area where aircraft are parked for loading, unloading, or maintenance.
- What is Partial Panel Operations? Flight conducted with limited or failed cockpit instruments, typically requiring reliance on backup or standby indicator...
- What is Parts awaiting supply? Maintenance action deferred because required replacement part is not yet available in inventory or supply chain.
- What is Passenger announcement? Any formal communication delivered to passengers by flight or cabin crew via public address system regarding flight info...
- What is Passenger brace? Command for passengers to adopt the brace position to minimise injury risk during hard landing or severe turbulence.
- What is Passenger count? The official total number of passengers on board, verified by cabin crew and reported to the flight deck before departur...
- What is Passenger manifest? An official list of all passengers onboard an aircraft, required by aviation regulations for tracking, safety, and emerg...
- What is Passenger Oxygen Mask Deployment? The automatic or manual release of oxygen masks for passengers in response to cabin depressurization or smoke.
- What is Passenger service unit? Overhead module above each seat row housing reading light, call button, air vent and oxygen mask panel.
- What is Passing? A term used by pilots to report the altitude they are currently climbing or descending through.
- What is Performance Penalty? A reduction in aircraft performance, such as climb, takeoff, or landing, resulting from inoperative systems or configura...
- What is Performance-Based Navigation? A framework for area navigation based on required performance standards for accuracy, integrity, and functionality (ICAO...
- What is Performance-Based Navigation? A navigation specification that requires aircraft to meet specific performance requirements for accuracy, integrity, con...
- What is Performance-Based Navigation Approval? An operational authorisation indicating an aircraft and crew are approved to operate using specific performance-based na...
- What is Pet in-cabin? A pet permitted to travel in the aircraft cabin with the passenger, subject to airline policies and operational restrict...
- What is Pitot cover installed? Protective pitot-tube cover still fitted, blocking dynamic-pressure input and rendering airspeed indications unreliable.
- What is pitot probe? A forward-facing tube that measures dynamic air pressure, providing critical input for airspeed indication.
- What is Pitot Tube Ice? Ice formation in the pitot tube, which can obstruct accurate airspeed measurement, potentially leading to unreliable or ...
- What is placard? An official sign or label installed in the cockpit or cabin to indicate equipment limitations, status, or required proce...
- What is Point? The ICAO/FAA radiotelephony word for the decimal mark in frequencies and altitudes, ensuring clarity in transmitting fig...
- What is Point of No Return? The specific point on the route after which an aircraft does not have sufficient fuel to return to the departure aerodro...
- What is Polar Air Route? A designated transcontinental flight path passing over the polar regions, generally used for efficient intercontinental ...
- What is Polar Diversion Site? A pre-designated airport suitable for emergency landing or diversion by polar-route aircraft, equipped and authorized fo...
- What is Portable electronic device? Any small battery-powered electronic item used by passengers, which may interfere with aircraft systems if not managed p...
- What is Portable oxygen? A movable oxygen supply unit provided on board aircraft for use by crew or passengers in case of medical need or cabin d...
- What is Position report? A report made by a pilot to ATC providing the aircraft's current position, altitude, and other relevant information.
- What is Positive rate? An indication, after takeoff, that the aircraft is climbing and the rate of climb is greater than zero as shown on the v...
- What is Potable water level? Indicates the current quantity of drinkable water available in the aircraft's potable water tanks; monitored by cabin or...
- What is Potable water quantity? The measured amount of safe, drinkable water stored in dedicated aircraft tanks, monitored for passenger and crew needs ...
- What is Potable water service? Ground operation involving the refilling of an aircraft’s drinking water tanks with safe, clean, and potable water.
- What is Power over Ethernet in Avionics? A system that delivers both power and data over Ethernet cables to avionics equipment, reducing wiring complexity and en...
- What is power transfer unit? A hydraulic unit that enables power transfer between two separate hydraulic systems without mixing their fluids.
- What is Powerback forbidden? A restriction prohibiting aircraft from using engine thrust in reverse to move backward from the gate or stand.
- What is Pre-flight briefing? A mandatory operational meeting or exchange held prior to flight, covering crew assignments, weather, NOTAMs, operationa...
- What is Pre-start? The phase prior to engine start during which pilots perform pre‑start checklists, request clearances, and coordinate wit...
- What is Predictive Maintenance? A maintenance approach using data analytics, sensors, and machine learning to predict equipment failures and schedule re...
- What is pressure altitude? Altitude indicated when the altimeter is set to the standard pressure setting of 1013.25 hPa (29.92 inHg).
- What is Pressure Altitude? The altitude indicated by a barometric altimeter set to the standard pressure setting of 1013.25 hPa or 29.92 inHg. Used...
- What is Pressure refueling? Refueling by forcing fuel under pressure through a closed coupling to aircraft tanks.
- What is prevailing visibility? Greatest visibility value equaled or exceeded for at least half the horizon.
- What is Pre‑conditioned air? Air that has been heated or cooled and dehumidified before being supplied to an aircraft on the ground.
- What is Pre‑takeoff check? A required inspection or verification immediately before departure, ensuring that aircraft critical surfaces are free of...
- What is primary flight computer? The Boeing main computer responsible for integrating pilot inputs, aircraft data, and actuating control surfaces.
- What is primary flight display? The main instrument display showing attitude, speed, altitude, heading, and flight director information.
- What is Primary Flight Display? The main electronic cockpit display providing essential flight information such as attitude, airspeed, altitude, and hea...
- What is Prist? A proprietary fuel system icing inhibitor (FSII) additive, often used in jet fuel to prevent the formation of ice crysta...
- What is Proceed direct? An ATC instruction authorizing an aircraft to fly directly to a specified point, bypassing the previously assigned route...
- What is Proceed via? An ATC instruction directing an aircraft to follow a specified route, airway, or series of waypoints.
- What is Prognostic Chart? A weather chart produced by meteorological authorities that forecasts the expected positions of pressure systems, fronts...
- What is Protective breathing equipment? A certified, self-contained smoke hood that provides crew with filtered air for a limited time in the presence of smoke ...
- What is Protective breathing equipment missing? Required PBE smoke-hood absent from crew station or galley, violating safety regulations until replaced.
- What is Public address system? Aircraft Public Address (PA) system, used by flight and cabin crew for delivering announcements, emergency messages, and...
- What is Pushback? The procedure of moving an aircraft rearward from a gate or stand using a tow vehicle, under ground control instructions...
- What is Pushback and start approved? ATC clearance authorizing an aircraft to begin pushback from the gate and start engines.
- What is Pushback approved? An air traffic control authorization allowing an aircraft to begin pushback from the gate or stand, typically in coordin...
- What is Pushback tractor? A motorized ground vehicle used to push aircraft backwards from the gate or parking position, typically before engine st...
Q
- What is QFE (Altimeter setting to runway threshold elevation)? An altimeter reference setting in which the altimeter indicates the height above the runway threshold elevation; used fo...
- What is QNH? The altimeter subscale setting that causes the altimeter to read elevation above mean sea level at an airfield. Used pri...
- What is Quebec? The letter 'Q' as spoken in the ICAO phonetic alphabet, used in ATC phraseology for identification of taxiways, holding ...
- What is Quick Access Recorder? An on-board device that rapidly records selected flight parameters for operational monitoring and safety analysis, with ...
- What is Quick Reference Handbook? A cockpit manual containing condensed checklists and procedures for abnormal and emergency situations.
R
- What is Radar contact? Indication that a particular aircraft is identified on the radar display and radar flight following will be provided
- What is Radar service terminated? ATC instruction indicating that radar monitoring and associated services are no longer being provided; the pilot must no...
- What is Radio Magnetic Indicator? An instrument displaying the aircraft's bearing to selected radio navigation aids, combining magnetic heading and bearin...
- What is Raft pack? A compact package containing the liferaft and emergency equipment required for survival after ditching, stowed on board ...
- What is Ram Air Inlet? An air intake system that uses forward motion of the aircraft to force external air into ducts for ventilation or pressu...
- What is Ram Air Inlet Door Failure? A malfunction where the ram air inlet door fails to open or close properly, affecting ventilation and cooling of avionic...
- What is ram-air turbine? A small turbine deployed in flight to provide emergency hydraulic or electrical power using airflow.
- What is Ramp agent? A ground operations staff member responsible for guiding aircraft to and from gates, loading and unloading baggage, and ...
- What is Ramp Lead? A supervisory ground crew member responsible for coordinating ramp operations and leading a team during aircraft turnaro...
- What is Ramp safety? Operational procedures and regulations ensuring the safe movement and coordination of aircraft, vehicles, and personnel ...
- What is ramp weight? The total weight of the aircraft while parked at the ramp, including fuel, payload, and all crew and equipment before en...
- What is Rapid Decompression? A sudden and unexpected loss of cabin pressure, requiring immediate descent and use of supplemental oxygen.
- What is RAT temperatures? Temperatures measured by the Ram Air Temperature (RAT) probe, used for performance calculations and fluid blending ratio...
- What is Read back? A procedure where the receiving station repeats a received message or its pertinent parts to confirm accurate reception.
- What is Readback correct? A phrase used by ATC to confirm that the pilot's readback of instructions is accurate.
- What is Reading light? Seat-specific overhead lamp in PSU providing adjustable illumination for passengers.
- What is Ready for departure? A phrase used by pilots to indicate they are prepared to begin the takeoff roll.
- What is Ready for pushback? A phrase used by pilots to indicate they are prepared for the aircraft to be pushed back from the gate.
- What is Ready for taxi? A phrase used by pilots to indicate they are prepared to begin taxiing.
- What is Ready to copy? A phrase used by pilots to indicate they are prepared to receive and write down instructions or clearances.
- What is recirc fan? A fan that recirculates cabin air, mixing it with conditioned air to improve efficiency and reduce bleed air demand.
- What is Rectification interval extension? Formal approval to extend the allowable period for repair of a deferred defect beyond original MEL interval.
- What is Redispatch Clearance? Official authorization given at a predetermined point, permitting continuation to the planned destination or re-clearanc...
- What is Redispatch Point? A designated waypoint or position along the route after which flight dispatch is revalidated or amended based on updated...
- What is Redispatch Release? A flight release authorizing a change of destination or continuation beyond a point after departure, subject to operatio...
- What is Reduce speed? A phrase used to instruct the pilot to decrease the aircraft's speed.
- What is reduced vertical separation minimum? A set of airspace procedures allowing aircraft to be separated by 1,000 feet vertically above FL290, increasing airspace...
- What is Reduced Vertical Separation Minimum Approval? An official authorisation for an aircraft and operator to use Reduced Vertical Separation Minimum (RVSM) airspace, allow...
- What is Reduced-Thrust Take-Off? Take-off using less than maximum rated thrust by performance calculation, saving engine life and fuel.
- What is Reference landing speed? The speed selected as a reference for final approach and landing, often denoted as Vref; used for approach calculations ...
- What is reference landing speed? Target speed established by crew to optimize landing safety and performance, typically VREF plus wind correction.
- What is Rejected Take-Off? A procedure in which a take-off is intentionally aborted by the flight crew after the aircraft has started to roll but b...
- What is Remote stand? An aircraft parking stand located away from the terminal building, typically requiring bus transport for passengers.
- What is repair interval? The maximum period permitted by the MEL for rectifying an inoperative item before mandatory maintenance is required.
- What is repeat item? A recurring defect or observation required to be checked, recorded, or repeated at intervals specified in the MEL or log...
- What is Report? An instruction for the pilot to provide specific information, such as position, altitude, or status, either once or at s...
- What is Report established? An instruction for the pilot to inform ATC when the aircraft is established on a specified segment of the approach, typi...
- What is Report final? An instruction for the pilot to inform ATC when the aircraft is on the final approach segment, aligned with the runway c...
- What is Report passing? An instruction for the pilot to notify ATC when passing through a specific altitude or level.
- What is Report reaching? An instruction to notify ATC when a specified altitude or level has been attained.
- What is Report vacated? An instruction to inform ATC when the aircraft has completely left the runway.
- What is Required Communications Performance 240? A globally standardized measure for communications capability, latency, and integrity in airspace—‘240’ indicates messag...
- What is required navigation performance? A set of precision standards for aircraft navigation accuracy, integrity, and reliability within defined airspace or pro...
- What is Required Navigation Performance? A statement of the navigation performance accuracy necessary for operation within a defined airspace, expressed as a num...
- What is Required Navigation Performance Authorisation-Required Approach? A specific approach procedure requiring both Required Navigation Performance (RNP) and explicit operational authorisatio...
- What is Required Navigation Performance Authorization Required? A navigation specification for RNAV operations that requires special aircrew and aircraft authorization before use, typi...
- What is Required Navigation Ten? A navigation specification requiring aircraft to maintain a track-keeping accuracy of ±10 nautical miles for at least 95...
- What is Rescue Coordination Center? A designated center responsible for organizing and coordinating search and rescue operations in a specified area, as def...
- What is Reserve fuel? The quantity of fuel carried on board in addition to all planned requirements, intended for unforeseen circumstances and...
- What is Restraint kit? A set of approved equipment provided to cabin crew for the physical restraint of an unruly or dangerous passenger to ens...
- What is Restraint kit? Cabin crew kit containing cuffs, straps or ties used to restrain unruly passengers.
- What is Resume own navigation? Instruction for the pilot to return to their own pre-filed or previously assigned route after deviation or vectoring.
- What is Retard thrust levers? Callout or instruction for pilots to move all engine thrust levers to idle, normally at 20–10 ft AGL during Airbus landi...
- What is Rime ice? A rough, white, opaque ice that forms rapidly from supercooled water droplets freezing on aircraft surfaces, reducing ae...
- What is Rime Icing? The formation of rough, milky, opaque ice due to rapid freezing of supercooled water droplets on aircraft surfaces.
- What is RNAV Route? A published airway or route defined by area navigation (RNAV) waypoints, allowing aircraft to fly direct between points ...
- What is Roger? A standard radiotelephony term meaning 'I have received all of your last transmission'; it does not imply compliance or ...
- What is Roll-out mode? A mode of the autopilot or autoland system engaged after touchdown, controlling the aircraft's direction and deceleratio...
- What is Romeo? The letter 'R' as spoken in the ICAO phonetic alphabet, used in ATC phraseology to identify taxiways, holding points, an...
- What is Rotor Cloud? A turbulent, low-level cloud formation found downwind of mountain ranges, forming in the rotor zone beneath and near mou...
- What is Route Reclearance? An amended ATC clearance that modifies the previously cleared route, typically issued to avoid weather, airspace restric...
- What is Route Track Message? An ATC message providing route, track, or clearance information, typically via data link, for flights in procedural airs...
- What is Roving deadhead? A crew member assigned to reposition as a passenger (not working the flight), who may move between cabins or flights as ...
- What is Rudder Hardover? A condition in which the rudder deflects fully to one side due to system failure or malfunction, potentially causing sev...
- What is rudder trim? A flight-control adjustment that offsets rudder position to maintain coordinated flight and correct for yaw.
- What is Runback ice? Ice that forms aft of treated surfaces when anti-icing fluids are overwhelmed by supercooled water running back and free...
- What is Runway? A defined rectangular area on a land aerodrome prepared for the landing and takeoff of aircraft.
- What is Runway Condition Assessment Matrix? A standardized tool used to report runway surface condition for operational decision-making, using runway condition code...
- What is runway condition report? Aerodrome-issued report of runway surface condition using RCAM and RWYCC.
- What is Runway Excursion? An incident where an aircraft veers off or overruns the runway surface during take-off or landing.
- What is runway friction? Measurement of friction coefficient between tires and runway; indicates braking performance.
- What is Runway Incursion? Any occurrence at an aerodrome involving the incorrect presence of an aircraft, vehicle, or person on the protected area...
- What is Runway turn-off? A designated taxiway or exit used by an aircraft to vacate the runway after landing or rejected takeoff.
- What is Runway vacated? Confirmation that the aircraft has exited the runway.
- What is runway visual range? The distance over which a pilot of an aircraft on the centre line of a runway can see the runway surface markings or lig...
- What is runway visual range? Distance over which runway markings or lights are visible from centreline on approach.
- What is Runway Visual Range Seventy-Five Metres? Reported horizontal distance a pilot can see runway markings or lights, measured at 75 metres for CAT IIIB minima.
- What is runway‑length correction for slope and temperature? Adjustment applied to declared runway length to account for runway slope and ambient temperature effects on aircraft per...
S
- What is Safety alert? A warning issued to alert the pilot of an immediate safety concern.
- What is Safety card? Printed passenger safety-instruction card found in every seat pocket, showing required actions and equipment use in an e...
- What is Safety cone? A brightly colored, cone-shaped marker placed around aircraft or equipment to designate safety zones and prevent collisi...
- What is Safety demo? A mandatory demonstration by the cabin crew, conducted prior to takeoff, showing passengers the use of safety equipment ...
- What is Safety Demonstration Kit? Standardised set of visual aids and demo seat-belt used by cabin crew to brief passengers on emergency equipment and pro...
- What is Safety information card? Printed card in seat pocket detailing aircraft emergency equipment and evacuation procedures.
- What is Safety Management System Process? A structured set of procedures within an SMS for identifying, assessing, and mitigating operational safety risks in avia...
- What is safety valve? A valve designed to automatically relieve excess pressure or vacuum to protect the aircraft structure.
- What is satellite communication? A long-range communication system using satellites, enabling cockpit and company contact beyond VHF and HF range.
- What is Satellite-Based Augmentation System? A satellite navigation system that augments GNSS signals, providing improved accuracy, integrity, and availability for a...
- What is Say again? A phrase used to request the repetition of all or part of a previous transmission.
- What is Scheduled component change? Pre-planned replacement of a part or system component at a specified interval or due time according to maintenance sched...
- What is Scheduled component change? Pre-planned replacement of an aircraft component at specific intervals in accordance with the maintenance schedule.
- What is Sea Dye Marker? Bright fluorescent dye packet released into water to create high-contrast slick, aiding aerial visual location of surviv...
- What is Seat belt? Primary restraint harness securing an aircraft occupant during all phases of flight and turbulence.
- What is Seat pocket? Fabric or plastic pocket on seat-back for storing safety card, magazines and small personal items.
- What is Seat recline lock? Mechanical latch preventing a passenger seat from reclining, used during take-off, landing or when inoperative.
- What is Seat-Belt Cutter? Knife-type tool with guarded blade carried in cockpit or cabin to sever jammed seat-belts during emergency evacuation or...
- What is Seat-Belt Extender? Certified strap and buckle section that lengthens a passenger seat belt when required for fit or special needs.
- What is Seatbelt sign? An illuminated sign in the aircraft cabin that instructs passengers to fasten their seatbelts.
- What is Second fluid? A protective de-icing or anti-icing fluid applied after first fluid, designed to prevent further accumulation of ice or ...
- What is Secure area? A designated zone within an airport or airside area where access is restricted to authorized personnel for security purp...
- What is Secure Boot Process? A cryptographic method that ensures only authorized software can be loaded on avionics systems during startup (EASA, ICA...
- What is Security briefing? A formal communication given to crew or passengers outlining relevant safety, emergency, and security procedures for the...
- What is Security Search? An official inspection of an aircraft or passengers by security personnel to ensure no security threats are present.
- What is Security ties? Approved plastic or textile ties used by the crew to restrain passengers or secure items for safety or security purposes...
- What is Sequencing? The process of arranging aircraft in a specific order for arrival, approach, or departure, ensuring safe and efficient f...
- What is Service bulletin pending? Manufacturer’s recommended modification or inspection not yet incorporated; outstanding action listed in maintenance rec...
- What is Service difficulty report? Official report filed to aviation authority documenting significant aircraft/system in-service malfunction, defect, or r...
- What is Service door? A designated aircraft door used primarily for catering, cleaning, or maintenance services, not intended for passenger us...
- What is Service irregularity? Any deviation from normal operating procedures, schedules, or expected service standards during a flight or at the airpo...
- What is Seven? The digit '7' as spoken in the ICAO radiotelephony alphabet, pronounced 'Seven' for clarity in altitude, heading, runway...
- What is Severe Turbulence? Turbulence causing large, abrupt changes in altitude and/or attitude, usually resulting in momentary loss of control and...
- What is severe turbulence? Turbulence that causes large, abrupt changes in altitude and/or attitude. Aircraft may be momentarily out of control. Oc...
- What is Short final? The segment of the final approach path closest to the runway.
- What is Short-Term Trend Forecast? A TREND appended to a METAR or SPECI giving expected significant changes in surface wind, visibility, weather or cloud o...
- What is Shutdown? The procedure in which the aircraft's engines and systems are switched off after reaching the parking position, ending t...
- What is Sidestep? A maneuver to change from one parallel runway to another during approach.
- What is Sierra? The letter 'S' as spoken in the ICAO phonetic alphabet, used in ATC phraseology to identify taxiways, holding points, an...
- What is Signal mirror? A reflective device included in survival kits, used to attract attention and signal rescue aircraft or ships in daylight...
- What is Signal Smoke? Hand-held maritime flare producing coloured smoke during daylight to signal distress location to aircraft or vessels.
- What is Significant Meteorological Information? A weather advisory issued by a Meteorological Watch Office concerning significant en‑route weather hazards affecting fli...
- What is Significant Temperature Level? A specific altitude or flight level at which temperature changes are forecast to be significant for flight operations, a...
- What is Significant Weather Chart? A meteorological chart that displays forecasted significant weather phenomena, including turbulence, icing, and cumuloni...
- What is Single European Sky Air Traffic Management Research? A pan-European collaborative project (SESAR) for research and development of next-generation air traffic management, sta...
- What is Single-point fueling? Method of pressurised refueling using one connector that simultaneously feeds all aircraft tanks.
- What is Six? The ICAO/FAA radiotelephony spelling for the numeral '6'. Used for unambiguous communication of headings, altitudes, fre...
- What is Skew-T Log-P Diagram? A thermodynamic diagram used in meteorology to plot atmospheric soundings, displaying temperature, dew point, and wind p...
- What is Sky shop? An onboard retail service offered to passengers, typically involving the sale of duty-free goods during flight.
- What is Slats? Movable aerodynamic surfaces located on the leading edge of the wing, extended to increase lift at low speeds during tak...
- What is Slide armed? A condition in which an aircraft's emergency evacuation slide is mechanically engaged to deploy automatically upon door ...
- What is Slide deployment? Activation of an inflatable evacuation slide from an aircraft door to enable rapid passenger egress.
- What is Slide disarmed? A state in which an aircraft's emergency evacuation slide is mechanically disengaged so it will not deploy if the door i...
- What is Slide pressure? Gauge-indicated reservoir pressure that confirms an emergency evacuation slide is sufficiently charged for rapid inflati...
- What is Slide raft? Inflatable evacuation slide that converts to a life-raft for ditching or over-water evacuation.
- What is Slides armed? Confirms that the emergency evacuation slides are engaged and will deploy automatically if the door is opened.
- What is Slides disarmed? The condition in which the emergency evacuation slides are disengaged from automatic deployment, typically after arrival...
- What is Slides disarmed? Indicates that the emergency evacuation slides are disengaged from the doors and will not deploy if the door is opened.
- What is Slow? A phrase used to instruct the pilot to reduce speed.
- What is Smoke detector? An electronic device installed in aircraft compartments, especially lavatories and cargo, to detect smoke and trigger an...
- What is Smoke Drill? A practiced emergency procedure used by flight or cabin crew to respond to smoke or fire in the aircraft.
- What is Smoke hood? A self-contained hood providing filtered air to crew in smoke or fume-filled environments; enables safe intervention in ...
- What is Snow accumulation? The build-up of snow on airport surfaces, aircraft, or equipment, affecting operations, safety, or performance.
- What is Snow Notice to Airmen? Special NOTAM issued when snow, ice or slush significantly affects aerodrome movement areas.
- What is Spare masks? Additional oxygen masks stored onboard to supplement the fixed oxygen system for crew or passenger use.
- What is Special Aerodrome Report? An unscheduled aerodrome weather report issued when significant meteorological changes occur between routine METARs.
- What is Special meal? A meal specially requested to meet specific dietary, religious, or medical requirements for individual passengers, to be...
- What is Special-Authorisation Category II? A precision approach and landing operation using Category II minima that requires special authorisation by the state of ...
- What is Special-Authorisation Category III? A precision instrument approach and landing operation with the lowest decision heights and runway visual range (RVR), re...
- What is Speed? The rate at which an aircraft is moving through the air, usually expressed in knots.
- What is Speed brake? A flight control surface deployed by pilots to increase drag and reduce airspeed or descent rate, especially during desc...
- What is speed-brake lever? A cockpit control that arms or actuates spoiler panels to reduce speed or rate of descent during flight and landing roll...
- What is Spoiler Deactivated? A system status where one or more spoiler panels are intentionally or automatically rendered inoperative for the flight.
- What is spoiler panel? A hinged surface on the upper wing that disrupts airflow, reducing lift and increasing drag for roll control or descent.
- What is spoiler-elevator computer? An Airbus computer managing spoilers, elevator backup, and other flight control surfaces for redundancy and flight envel...
- What is Spoilers? Movable surfaces on the wings deployed to reduce lift, increase drag, and assist in decelerating the aircraft after touc...
- What is Spray bar? A component of de-icing or anti-icing equipment that distributes fluid evenly across aircraft surfaces for contaminant r...
- What is squall? Sudden increase in wind speed of at least 15 knots, sustained for at least one minute.
- What is Squawk? An instruction for a pilot to set a specific transponder code, enabling air traffic control to identify and track the ai...
- What is Squawk ident? An ATC instruction to activate the IDENT feature on the aircraft's transponder, which causes the radar return to flash, ...
- What is Squawk standby? An instruction for a pilot to set the aircraft's transponder to standby mode, ceasing transmission of the transponder si...
- What is stabilizer trim? The adjustment of the horizontal stabilizer angle to balance the aircraft in pitch for all flight phases.
- What is Stall Warning? An alert that warns the pilot of an impending aerodynamic stall, usually through audible or tactile signals like a horn ...
- What is Stand? A designated area where an aircraft is parked for loading, unloading, or maintenance.
- What is Stand by? An instruction meaning 'wait and I will call you'; it indicates that the controller or pilot is temporarily unable to co...
- What is Standard departure? A pre-planned IFR departure route (SID) published for use by departing aircraft, providing obstacle clearance and effici...
- What is Standard Instrument Departure? A published IFR departure procedure providing specific routing, altitude, and navigational guidance for departing aircra...
- What is Standard pressure setting (1013 hPa)? The standard sea-level pressure value of 1013.25 hPa (hectopascals) used above transition altitude/level for setting alt...
- What is Standard Terminal Arrival Route? A published IFR route that provides standardized lateral and vertical guidance for arriving aircraft from the en-route s...
- What is standard‑atmosphere temperature lapse rate? The rate at which temperature decreases with altitude under standard atmospheric conditions, 2 °C per 1000 ft or 6.5 °C ...
- What is Standby ADIRU? Independent backup ADIRU providing attitude, heading, and air-data when primary systems are degraded or failed.
- What is Standby crew? Crew members held in reserve at the airport, ready to replace or supplement operating crew as required by airline or reg...
- What is Standby Instrument System? An independent set of basic flight instruments that provide critical information in case of primary display failure.
- What is Standing Lenticular Cloud? A smooth, lens-shaped cloud that forms at high altitudes in the crest of mountain waves; often stationary, and indicativ...
- What is Stands? Designated areas on the apron where aircraft are parked for boarding, servicing, or loading/unloading operations.
- What is STAR? Standard Terminal Arrival Route: a published IFR arrival procedure that streamlines traffic flow from the enroute phase ...
- What is Start-up approved? ATC clearance authorizing the aircraft to start its engines, typically when pushback is not required.
- What is Static bond? Earthing connection between aircraft and fuelling equipment used to equalise electrical potential and prevent electrosta...
- What is static port? An external opening on an aircraft that senses ambient atmospheric pressure for use by the pitot-static system.
- What is Static Port Blockage? An obstruction in the static pressure port of an aircraft, leading to erroneous altitude, airspeed, and vertical speed i...
- What is Static wick missing? Static electricity discharge wick absent from wing or control surface, potentially increasing radio interference until r...
- What is steer-by-wire? A digital control system where electronic signals, not mechanical linkages, direct the nose-gear steering.
- What is Step climb? A procedure in which an aircraft increases cruise altitude in steps as weight decreases, optimizing fuel efficiency and ...
- What is Step Climb? A series of planned altitude increases during cruise, typically due to decreasing aircraft weight from fuel burn, allowi...
- What is Step Climb Profile? A flight profile in which an aircraft increases cruise flight level in stages as weight decreases and conditions permit,...
- What is Sterile cockpit? A mandatory operational environment during critical phases of flight—such as taxi, takeoff, landing, and below 10,000 fe...
- What is Stick Shaker Activation? The activation of a device that rapidly vibrates the control column to warn the pilot of an impending aerodynamic stall.
- What is Stop sign? A clearly marked sign on the apron or taxiway instructing aircraft or vehicles to come to a complete stop and await furt...
- What is stopway length? The length of a stopway usable in the event of a rejected take-off, beyond the take-off run available.
- What is supercooled large droplet? Liquid droplets below freezing point that can remain liquid until striking an object.
- What is Surface Analysis Chart? A weather chart depicting current meteorological features such as pressure systems, fronts, and precipitation areas at t...
- What is Surface Movement Guidance and Control System? A comprehensive system of lighting, signs, and procedures to support safe and efficient aircraft movement on the ground,...
- What is Survival beacon? A portable transmitter emitting distress signals to assist search and rescue teams in locating survivors after a forced ...
- What is Survival kit? A set of equipment carried on board aircraft and liferafts to provide basic survival supplies such as food, water, and s...
- What is Survival Rations Pack? Pre-sealed emergency food package stowed in life-rafts providing high-energy biscuits and vitamin tablets for post-ditch...
- What is Survival Strobe Light? Battery-powered high-intensity flashing beacon attached to life-vest or raft to enhance night-time visibility for rescue...
- What is Switch to? Instruction to change the aircraft's communication radio frequency to another specified ATC unit or frequency.
- What is Synthetic Vision Guidance System? A cockpit display system that provides pilots with a computer-generated, real-time, 3D depiction of terrain, obstacles, ...
- What is system synoptic display? A cockpit display providing a schematic overview of aircraft systems’ status, such as hydraulics, electrics, fuel, and a...
- What is System-Wide Information Management? A global aviation data-sharing infrastructure standardizing information exchange among ATM stakeholders, improving situa...
T
- What is Tactical Air Navigation? A military navigation system (TACAN) providing bearing and distance information to aircraft, functionally similar to VOR...
- What is Tail Strike? An incident in which the tail of the aircraft contacts the runway surface during take-off or landing due to excessive pi...
- What is Tail-wind component? The portion of the wind velocity blowing in the same direction as the aircraft's movement or runway orientation, reducin...
- What is Take-off distance available? Declared length of runway plus clearway that is available and suitable for the ground run of an aircraft taking off.
- What is Take-off run available? Declared length of runway suitable for the ground run of an aircraft taking off, excluding clearway.
- What is Take‑off roll? The phase of flight beginning when an aircraft starts its ground run on the runway after take-off clearance, acceleratin...
- What is take‑off safety speed? Target airspeed reached after V2 during take‑off, providing sufficient climb gradient with one engine inoperative.
- What is Tango? The letter 'T' as spoken in the ICAO phonetic alphabet, used in ATC phraseology to clearly identify taxiways, holding po...
- What is Tank inerting? The process of introducing an inert gas, usually nitrogen, into an aircraft fuel tank to reduce oxygen concentration and...
- What is Tankering Decision? The operational determination to carry extra fuel for economic or logistical reasons, usually based on fuel pricing and ...
- What is Task card completed? Documented evidence that all steps of an assigned maintenance task card have been performed and signed off.
- What is Taxi? To move an aircraft on the surface of an aerodrome under its own power, except when taking off and landing. Used in ATC ...
- What is Taxi guidance line? A painted marking on an airport surface that provides directional guidance for aircraft taxiing along specific routes.
- What is Taxi to? An ATC instruction authorizing an aircraft to proceed under its own power to a specified location on the aerodrome, such...
- What is Taxi via? An ATC instruction specifying the taxi route an aircraft must follow, indicating designated taxiways and any other routi...
- What is Taxi-in? The movement of an aircraft under its own power from the runway or landing area to the assigned parking position or gate...
- What is Taxiway? A path on an airport connecting runways with aprons, hangars, terminals, and other facilities.
- What is Taxiway? A defined path at an aerodrome, established for the taxiing of aircraft and intended to provide a link between one part ...
- What is taxi‑in fuel? Estimated fuel required for taxiing after landing, including clearing runway and reaching gate.
- What is taxi‑out fuel? Fuel required for engine start, taxi, and contingencies before take-off.
- What is Teardrop Entry? A method of entering a holding pattern in which the aircraft initially flies outbound on a course 30 degrees offset from...
- What is Technical Dispatch Sheet? A formal document or electronic record certifying an aircraft’s airworthiness and readiness for flight after maintenance...
- What is Temperature Inversion? A meteorological condition where temperature increases with altitude instead of decreasing, which can trap pollutants an...
- What is Terminal Aerodrome Forecast? A concise statement of the expected meteorological conditions at an aerodrome for a specified period.
- What is Terrain? The physical features of the land that may pose a hazard to aircraft.
- What is terrain awareness and warning system? Advanced system alerting pilots of hazardous terrain or obstacles using GPS and a terrain database, supplementing GPWS.
- What is Terrain Awareness Warning? A warning generated by aircraft systems indicating proximity to terrain that may result in controlled flight into terrai...
- What is Thermal Protective Aid? Insulated suit or bag carried in life-rafts to reduce hypothermia risk for survivors awaiting rescue in cold seas.
- What is Thousand? The ICAO/FAA radiotelephony word for '1000', used in expressing altitudes, heights, and visibility in multiples of one t...
- What is Three? The ICAO/FAA radiotelephony spelling for the numeral '3'. Used to clearly transmit numbers, altitudes, headings, runways...
- What is Threshold Crossing Height? The height above runway threshold at which the aircraft’s glide path crosses the runway during final approach, typically...
- What is Thrust reduction? A standard procedure to reduce engine thrust from take-off power to a lower, climb-appropriate setting at a specific alt...
- What is thrust reverser? A device used to redirect engine thrust forward to assist with deceleration after landing.
- What is Thrust reverser? A device that redirects the engine's thrust forward to help slow the aircraft after landing, typically activated on touc...
- What is Thrust Reverser Inoperative? The thrust reverser mechanism cannot be deployed, requiring alternative braking methods and possibly affecting landing p...
- What is thrust-lever angle? The position or angle of the thrust lever, directly corresponding to engine power demand.
- What is thunderstorm? Convective weather event with thunder, lightning, precipitation and possible severe turbulence.
- What is Time To Station? The calculated or measured time remaining to reach a radio navigation aid, waypoint, or fix, used for position reporting...
- What is Time-Based Separation? A separation technique in which aircraft are spaced by time intervals instead of distance to maximize runway throughput,...
- What is Time-Critical Checklist? A checklist containing emergency procedures that must be executed immediately to prevent loss of control or further dang...
- What is Top of climb? The defined point in a flight where the aircraft completes its climb and levels off at the planned cruise altitude. Mark...
- What is Top of Climb? The calculated point along the flight path where an aircraft completes its climb and levels off at cruising altitude as ...
- What is Top of descent? The calculated point during cruise at which an aircraft initiates descent from cruising altitude toward destination, usu...
- What is Top of Descent? The calculated point along a flight path where the aircraft begins its planned descent from cruise altitude toward the d...
- What is total pressure No. 2 probe? Sensor measuring total (pitot) pressure at engine station 2 for air data and engine control systems.
- What is total-air-temperature probe? A sensor on the aircraft that measures total air temperature, providing critical input for engine and air-data systems.
- What is Touch and go? A maneuver in which an aircraft lands on a runway and immediately takes off again without coming to a full stop.
- What is Towbar? A metal bar used to connect an aircraft's nose gear to a pushback tractor for towing or pushback operations.
- What is Towbarless tug? A powered ground vehicle that lifts the aircraft's nose gear and tows it without the need for a separate towbar.
- What is towering cumulus cloud? Large cumulus cloud with strong vertical development, indicating convective activity, but not yet cumulonimbus.
- What is Track? The aircraft’s actual path over the ground, measured in degrees from North. Distinct from heading, which is the directio...
- What is Track angle? The actual direction of an aircraft's path over the ground, expressed as an angle relative to north, independent of head...
- What is Traffic alert? A warning issued to alert the pilot of nearby aircraft that may pose a collision risk.
- What is Traffic Alert and Collision Avoidance System Resolution Advisory Reversal? An updated TCAS alert that instructs the flight crew to reverse a previously issued vertical avoidance maneuver due to a...
- What is traffic collision avoidance system? An airborne safety system providing pilots with traffic advisories and resolution advisories to avoid mid-air collisions...
- What is Traffic Collision Avoidance System Resolution Advisory? An instruction issued by the aircraft's TCAS system to avoid potential collision with another aircraft, advising a verti...
- What is Traffic in sight? Phrase used by pilots to confirm that they have visually acquired the reported traffic.
- What is Trailing-edge device? A movable aerodynamic surface located on the trailing edge of an aircraft wing, such as a flap, extended to increase lif...
- What is Trajectory-Based Operations? A concept where aircraft operations are planned, managed, and executed based on a shared, predicted four-dimensional tra...
- What is Transition? A published route or procedure that connects the en-route structure to an instrument approach or departure, often used t...
- What is Transition altitude? The altitude at or below which the vertical position of an aircraft is controlled by reference to altitudes, and above w...
- What is Transition level? The lowest flight level available for use above the transition altitude. Aircraft climbing through the transition altitu...
- What is Transition speed? The airspeed at which the transition from one phase of flight to another occurs, often referencing a speed for configura...
- What is Transponder Code 7700? The ATC transponder code universally set to indicate a general emergency, alerting controllers to an onboard emergency s...
- What is transponder control panel? Cockpit panel used for selecting, setting, and controlling aircraft transponder modes and codes.
- What is Transponder Failure? The aircraft’s transponder is not transmitting, impacting radar identification and requiring ATC notification and altern...
- What is Transport Layer Security for Avionics? The use of cryptographic protocols (TLS/SSL) to protect avionics network data in transit from unauthorized access or tam...
- What is Trash compactor? A mechanical device installed in the aircraft galley designed to compress and contain cabin waste for efficient storage ...
- What is Tray table latch? Mechanical catch that locks the passenger tray table in its stowed or deployed position.
- What is trim air? A system that adds small amounts of hot bleed air to the mixed supply to fine-tune cabin temperature zones.
- What is Trim Fuel Tank? A specialized fuel tank located in the horizontal stabilizer or tail, used to optimize aircraft balance and fuel managem...
- What is Trolley seals? Tamper-evident security seals affixed to galley trolleys or beverage carts to ensure contents have not been accessed bet...
- What is Tropical Air Route? An airway or designated flight route that traverses tropical climate regions, often with unique meteorological and navig...
- What is Tropical Cyclone Significant Meteorological Information? A SIGMET issued for a tropical cyclone within or approaching an FIR, including observed or forecast TC position, extent ...
- What is tropopause? The boundary layer between troposphere and stratosphere, marked by a temperature inversion, affecting flight levels and ...
- What is Tropopause Height? The altitude at which the troposphere ends and the stratosphere begins, critical for flight planning due to temperature ...
- What is Troubleshooting required? Further diagnostic action needed to isolate cause of technical fault or failure not resolved by initial inspection.
- What is True airspeed? The actual speed of an aircraft relative to the air mass through which it is flying, corrected for altitude and temperat...
- What is True Course? The intended direction of flight over the ground referenced to true north, prior to adjustment for wind, magnetic variat...
- What is Turbulence? Irregular motion of the air resulting from eddies and vertical currents, often causing bumpiness or abrupt altitude chan...
- What is turbulence? Irregular atmospheric motion caused by eddies and vertical currents, affecting aircraft stability, comfort, and sometime...
- What is Turbulence procedure? A set of operational safety steps followed by flight and cabin crew when turbulence is encountered or anticipated, inclu...
- What is Turbulence Procedure? A set of prescribed actions for flight crew to follow when encountering turbulence, including changes in altitude, speed...
- What is Turn left? An instruction to change aircraft heading by initiating a left turn.
- What is Turn right? An instruction from ATC to initiate a right turn onto a specific heading, route, or to avoid traffic or terrain.
- What is Turnaround? The time taken to unload an arriving aircraft and prepare it for departure, including disembarkation, cleaning, refuelin...
- What is Two? The ICAO/FAA radiotelephony spelling for the numeral '2'. Used to communicate numbers, headings, altitudes, flight level...
- What is Type I fluid? A heated, glycol-based de-icing fluid used primarily to remove frost, ice, and snow from aircraft surfaces before depart...
- What is Type II fluid? A glycol-based anti-icing fluid with higher viscosity than Type I, applied to aircraft surfaces to prevent ice accumulat...
- What is Type III fluid? A low-viscosity anti-icing fluid designed for slower aircraft, offering both de-icing and anti-icing properties with lim...
- What is Type IV fluid? A high-viscosity, anti-icing fluid used on fast, jet aircraft to provide maximum holdover time and surface protection ag...
U
- What is Ultra Long Haul? A non-stop flight covering an exceptionally long distance, typically over 16 hours or more than 7,000 nautical miles, re...
- What is Unable? A phrase used by pilots to indicate they cannot comply with a specific instruction or clearance.
- What is Unaccompanied minor? A child travelling alone without a legal guardian, requiring airline supervision and special handling procedures as per ...
- What is unchanged? Minimum vertical profile flown after take‑off, reduced from gross climb to ensure obstacle clearance following critical-...
- What is unchanged? Climb segment from gear retraction to acceleration altitude with one-engine inoperative, maintaining prescribed gradient...
- What is unchanged? Climb segment after acceleration and flap retraction up to en‑route climb altitude with one-engine inoperative.
- What is unchanged? Minimum climb performance required during a go-around or missed approach with all engines operating.
- What is unchanged? Imaginary inclined plane established to ensure minimum safe vertical separation between aircraft flight paths and obstac...
- What is Unchanged? Lowest climb gradient required to ensure obstacle clearance or meet procedure design criteria.
- What is Unchanged? The highest level of engine thrust that can be used continuously without time limitation under normal operating conditio...
- What is Unchanged? Reduced engine thrust setting used for take-off to extend engine life, improve fuel efficiency, and meet noise abatement...
- What is Unchanged? Take‑off Using An Assumed Temperature Higher Than Actual To Reduce Thrust And Prolong Engine Life While Meeting Performa...
- What is Unchanged? Thrust Less Than Maximum Take‑Off Thrust Applied During Take‑Off To Increase Engine Life And Optimize Operational Effici...
- What is Unchanged? Numeric Value From 0 To 6 Indicating The Braking Action And Surface Condition Of A Runway As Published In A Runway Condi...
- What is Unchanged? Pilot‑reported Assessment Of Actual Aircraft Braking Performance On A Runway Surface.
- What is Unchanged? Standardized Tool Used To Assign Runway Condition Codes Based On Surface Type And Contaminant Characteristics, Supportin...
- What is Unchanged? Vertical Thickness Of Water, Slush, Or Other Moisture‑Related Contaminants On The Runway Measured In Millimetres For Per...
- What is Unchanged? Wind Blowing In The Same Direction As Aircraft Movement, Reducing Lift And Increasing Required Take‑Off Or Landing Dista...
- What is Unchanged? Wind Component Perpendicular To The Runway Centerline, Affecting Aircraft Lateral Control During Take‑Off And Landing.
- What is Unchanged? Wind Blowing Opposite To Aircraft Movement, Increasing Lift And Reducing Required Take‑Off Or Landing Distance.
- What is Unchanged? Length Of The Designated Area Beyond The Runway End That Can Be Used To Decelerate During A Rejected Take‑Off, As Part O...
- What is unchanged? Ground personnel positioned at each wingtip to ensure safe clearance of obstacles during aircraft ground movements.
- What is unchanged? A ground vehicle used to guide arriving or departing aircraft along taxiways or on the apron, especially in low visibili...
- What is unchanged? A ground crew member responsible for direct communication with the flight deck during pushback and engine start via inte...
- What is unchanged? A qualified person seated in the cockpit of a towed aircraft responsible for applying brakes if necessary during towing ...
- What is Uncommanded Rudder Input? An unintentional or spontaneous rudder movement not initiated by the pilot, potentially affecting aircraft yaw stability...
- What is Uniform? The letter 'U' as spoken in the ICAO phonetic alphabet, used in ATC phraseology for taxiways, holding points, or aircraf...
- What is Unit Load Device? Unit Load Device — a pallet or container used to load freight, mail, and baggage into aircraft cargo holds, standardized...
- What is Universal Precaution Kit? On-board kit with gloves, masks and absorbent agents for safe cleanup of blood or body-fluid spills.
- What is Unlawful Interference? An act of unlawful seizure, threat or attack against an aircraft, its passengers, crew or ground infrastructure that end...
- What is Unreliable Airspeed? A condition where the airspeed readings provided by the pitot-static system are incorrect or inconsistent, potentially l...
- What is Unruly Passenger? A passenger whose disruptive or violent behaviour interferes with the safety or order of the flight and crew instruction...
- What is Upper ATS Airway? A designated corridor in controlled airspace, typically above a specified flight level (e.g., FL245), for use by aircraf...
- What is Upper-Air Chart? A meteorological chart depicting wind, temperature, and pressure patterns at specified altitudes above the earth’s surfa...
- What is Upwind? The initial leg of the traffic pattern after takeoff, flown parallel to the runway and in the direction of departure.
V
- What is Vacate runway? An instruction to exit the runway at the nearest suitable exit.
- What is variable bleed valves? Adjustable engine valves that regulate bleed air extraction to maintain compressor stability and prevent stall.
- What is variable stator vanes? Adjustable compressor guide vanes that control airflow angle and optimize engine efficiency across operating conditions.
- What is variable‑reserve fuel? Additional reserve fuel calculated proportionally to flight time beyond the fixed reserve, for unforeseen delays.
- What is Vector? A heading assigned by ATC to an aircraft for navigation or separation purposes, usually stated as 'fly heading…'. Vector...
- What is Vectors? Heading instructions issued to provide navigational guidance by radar
- What is Vent panel? A dedicated panel or port that allows air pressure equalization or controlled venting in fuel tanks or systems, critical...
- What is Verify Flight-Mode Annunciator indications? Instructs crew to check and confirm that the Flight-Mode Annunciator (FMA) on the Primary Flight Display is showing the ...
- What is Vertical Navigation? A component of navigation relating to an aircraft's position in the vertical plane (altitude), including climb, cruise, ...
- What is Very High-Frequency Radio 1 Inoperative? Primary VHF radio channel 1 is not functional, requiring use of alternate radio or backup for ATC communications.
- What is very-high-frequency radio? Radio system in the VHF band (118–137 MHz) used for primary ATC voice communication within line-of-sight range.
- What is VHF omnidirectional range? A ground-based radio navigation system providing azimuth guidance to aircraft using VHF signals.
- What is VHF Omnidirectional Range? Ground-based VHF radio beacon providing 360-degree azimuth guidance to aircraft.
- What is Victor? The letter 'V' as spoken in the ICAO phonetic alphabet, used in ATC phraseology to indicate taxiways, holding points, or...
- What is visibility? Greatest distance at which prominent objects are visible and identifiable by day.
- What is Visual? A term used to describe operations conducted with visual reference to the terrain.
- What is visual‑segment surface? An obstacle‑free area beyond the runway threshold, providing required visual clearance during the final approach segment...
- What is Volcanic Ash Route? A temporary route planned to avoid areas of volcanic ash, based on current volcanic activity and advisories.
- What is Volcanic Ash Significant Meteorological Information? A SIGMET concerning volcanic ash clouds that may affect en‑route flight safety.
- What is VOR and TACAN Co-located Station? A ground-based radio navigation aid where a VHF Omnidirectional Range (VOR) and a Tactical Air Navigation (TACAN) facili...
- What is VOR Radial? A specific magnetic bearing from a VOR station, identified by its radial number, used for aircraft navigation and ATC in...
- What is VOR with Co-located DME? A navigation aid installation where a VHF Omnidirectional Range (VOR) and Distance Measuring Equipment (DME) are located...
W
- What is Warm Front? A boundary where a warm air mass advances and rises over a retreating cold air mass, usually resulting in steady precipi...
- What is Water Ditching Drill? A procedure practiced by cabin crew and passengers for emergency water landings, including life vest use, brace position...
- What is Water extinguisher? A portable fire extinguisher filled with water, intended for use on class A (solid material) fires onboard an aircraft.
- What is Water Landing? An intentional or emergency landing of an aircraft on a body of water due to operational necessity or system failure.
- What is Water paste? A chemical indicator applied to the end of a fuel tank dipstick to detect the presence of water at the bottom of aviatio...
- What is Water service cart? Ground-service trolley supplying potable-water fill or grey-water drain for aircraft tanks.
- What is Way-points? Specific geographical locations defined by coordinates used to guide aircraft along a flight route or procedure.
- What is Waypoint? A specified geographical location, defined by coordinates, used for navigation and flight planning, including RNAV proce...
- What is Waypoint Position Report? A mandatory ATC report specifying aircraft position, time, flight level, and estimates for the next waypoint, typically ...
- What is Weather Avoidance? Flight planning or tactical maneuvering to avoid hazardous weather areas using deviation, rerouting, or altitude changes...
- What is Weather Drift? Deviation from planned track or route due to wind or meteorological factors, often requiring heading or routing adjustme...
- What is Weight Penalty? An increase in operational weight or a reduction in allowable weight imposed due to specific inoperative equipment or co...
- What is Wheelchair WCHR? Wheelchair service code for a passenger requiring assistance to and from the aircraft but able to ascend and descend ste...
- What is Whiskey? The ICAO/FAA radiotelephony spelling for the letter 'W'. Used in call signs, aircraft registration, and waypoint identif...
- What is Whistle? A small signaling device, often attached to lifejackets, used by survivors to attract attention in rescue situations.
- What is Wide Area Augmentation System? A U.S.-based Satellite-Based Augmentation System (SBAS) that enhances GPS accuracy, integrity, and availability for all ...
- What is Wilco? A radiotelephony term meaning 'will comply'; it signifies that the message has been received, understood, and will be co...
- What is Wind and Temperature Aloft Message? A meteorological report providing forecasted wind direction, wind speed, and temperature at specific altitudes above mea...
- What is Wind Barb? A graphic symbol used on meteorological charts to represent wind speed and direction at a specific location and altitude...
- What is Wind check? A request for the current wind conditions at a specific location.
- What is wind shear? A sudden change in wind speed and/or direction over a short distance, hazardous during takeoff and landing.
- What is Window shade? Movable blind covering a passenger window to regulate light during flight phases.
- What is Winds? The current atmospheric conditions affecting aircraft movement.
- What is Windshear Escape Maneuver? A predefined and trained maneuver to escape from windshear conditions during takeoff or landing.
- What is wing anti‑ice? A system that prevents or removes ice accumulation on the wing leading edges using bleed air or electrical elements.
- What is Wing tank? A fuel tank located within the wing structure of an aircraft, commonly used for storage and balancing fuel load.
- What is Wingtip Clearance? The ensured safe distance between an aircraft’s wingtip and any obstacle, structure, or another aircraft during taxiing ...
- What is Work card reference? Unique identifier of a maintenance work card specifying approved procedures for inspection, repair, or modification.
Y
- What is yaw-damp system? An automatic system that prevents unwanted yaw oscillations by commanding the rudder, increasing flight comfort and stab...
- What is yellow hydraulic system? One of three independent hydraulic systems on Airbus aircraft, supplying power to specific flight controls, brakes, and ...
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