Aviation terms

Date of Last Revision: December 7, 2021
Plane wing

The universal language across the aviation industry is English, but there are some aviation terms that also have their roots in other languages like French, German, and sometimes military lexicon. However, even in English, aviation terms can use words with a totally different meaning than those in any other context. What’s more, aviation terms come in a handful of forms, such as abbreviations, acronyms, and slang.

So, whether you are a pilot or work in any other area of the aviation industry like operations management or safety management, it is important for you to be able to understand these terms and their definitions. To help you do just that, here we share our comprehensive glossary of aviation terms.


Absolute altitude

Absolute altitude is the distance measured vertically from the ground to the aircraft’s position in the air.

Absolute ceiling

It refers to the maximum aircraft’s altitude that can be reached for flying at full throttle, constant airspeed, and leveled position.

Accelerated stall

Stall happening at a higher airspeed than usual due to a higher load factor (g). This stall generally happens when the aircraft is going straight up or straight down and by making abrupt turns or control inputs in general.


This acronym refers to Automatic Dependent Surveillance-Broadcast. ADS-B is the main technology used for aircraft tracking. It is automatic because the system automatically sends the data required from the aircraft, meaning there’s no need for the pilot to intervene.

Also, the technology depends on the aircraft’s navigation system to get the information about the position, hence the “dependent” part of the acronym. Aircraft that use the ADS-B technology is capable of transmitting comprehensive information such as altitude, ground speed, and call sign. Additional information like airspeed, wind, and temperature can also be transmitted in some cases.

Adverse yaw

Adverse yaw describes the phenomenon of the nose of the aircraft moving away from the direction to the turn being performed. It also occurs when using ailerons, and the aircraft moves in the opposite direction of a roll due to the difference in lift and drag of each wing.


The second acronym in the list refers to Automatic Direction Finder, a navigation system that identifies the relative position and direction of movement of an aircraft according to a radio beacon broadcasted in the MF or LF bandwidth.

Adiabatic Lapse Rate

When there is thermal equilibrium, this rate represents the temperature changes resulting from altitude increases and decreases.

Aeronautical Decision-Making

Aeronautical decision-making is normally focused on controlling and containing risk, and it requires training and planning to make the best possible decisions.

Aeronautical Information Manual

Frequently abbreviated with the acronym AIM, the Aeronautical Information Manual is a highly detailed official publication issued by the Federal Aviation Administration (FAA) that provides instructions on how pilots must operate within the US National Airspace System, Air Traffic Control (ATC) procedures, and aviation safety. There are separate guides for the USA and Canada.


AGL is the acronym for Above Ground Level and refers to the vertical distance measured from the aircraft to a specific mass of land.


One of the movable control surfaces is placed on an aircraft wing and used to control the roll of an aircraft.

Aircraft age

It defines how old an aircraft is, usually counting from the first flight and considering both flying hours and pressurization cycles. It is not the same to have an airplane whose first flight was 10 years ago but has only flown 10,000 hours with 1,000 cycles than having an aircraft that first flew 5 years ago but has already flown 50,000 hours with 10,000 cycles.

Aircraft livery

Aircraft livery can be defined as the graphic design painted on it. Airlines often have a distinctive livery and create special liveries supporting events, anniversaries, or advertising campaigns.

Aircraft type

This refers to the standardized name for the aircraft, usually assigned to groups of aircraft with specific characteristics. Assigning the type code is done by ICAO. The codes are formed by two to four letters and numbers. The main use for the type codes is to simplify the identification of the aircraft when filing flight plans.

Air Defense Identification Zone

Airspace is divided into different zones, especially to identify which zone belongs to each country and for national security purposes. So, Air Defense Identification Zone, usually abbreviated by the acronym ADIZ, refers to the airspace requiring identification, location, and control of civil aircraft for national security purposes, including airspace over land and over water.


It is the shape of the cross-section of a surface that generates the lift necessary to flight when the air passes over it. Common surfaces on a plane with an airfoil include wings, blades, turbines, and rotors.


The name that is used for the company or organization that manages and offers scheduled flights and routes on a regular basis.

Airspace Classes

The types of airspace as defined by ICAO and adopted around the world. The airspace classes include controlled, uncontrolled, and special use.

Air Speed Indicator

Abbreviated with the acronym ASI, it is a flight instrument of the pitot-static type that indicates the aircraft’s airspeed flying through an air mass and measured in miles per hour, knots, or both of them.

Air Taxi Operator

An air taxi operator is a company that offers services according to FAR Part 135. This means the company operates small aircraft in the categories of turbojet engine powered aircraft with 1 to 30 seats, non-transport category turbo-propeller powered aircraft with 10 to 19 seats, and transport category turbo propellers with 20 to 30 seats. In general, small aircraft, normally under 30 seats. When carrying cargo, it should not exceed 18,000 pounds, and the company should work on either a scheduled or charter basis, on an on-demand basis or limited scheduled basis.

Air traffic control

Air traffic control is generally abbreviated with the acronym ATC, and it is responsible for coordinating flights during take-off, landing, and while flying. This ground-based service has the main goal of facilitating the movement of air traffic safely by preventing aircraft collisions and communicating directly with the pilot to provide vital information to achieve the objective.


This acronym is the abbreviation for Aviation Maintenance Technician. This is also a common name for an aircraft mechanic.


Another acronym. In this case, it stands for Aviation Medical Examiner, also known as Aero-Medical Examiner. According to the local aviation authority, it refers to a physician who has been given the authority to issue the corresponding medical certificates for flight operation.


The downward angle or inclination of an the wing of an aircraft in relation to a horizontal line in the cross-section of it.

Annual Inspection

A thorough inspection of an aircraft is required to go through every year.


This abbreviation refers to an Airframe and Powerplant Mechanic, the certified person to carry out maintenance and alterations on an aircraft in an independent manner.


The name of the flight phase before landing is where the pilot prepares to take the aircraft to the ground.


This is the area of an airport prepared for the aircraft to park, fuel, load, and unload.

Area Navigation

Abbreviated with the acronym RNAV, it is a method of IFR navigation where a network of radio beacons is provided for the aircraft to take the course instead of navigating from and to beacons directly.


This is the acronym used for Automatic Terminal Information Service. It involves pre-compiled messages broadcasting on an airwave frequency at international airports. ATIS information includes weather conditions and runway use, approach type, and approachable style, and air traffic controllers usually provide it.

Auxiliary power unit

Abbreviated with the acronym APU, the auxiliary power unit is usually a jet engine located in the tail cone of an aircraft which provides autonomy for operation without needing external equipment like a ground power unit, an external air-conditioning unit, or a high-pressure air start cart.

Automatic Direction Finding

Abbreviated ADF, the Automatic Direction Finding is an electronic device that helps navigation by identifying the relative bearing of an aircraft from a radio beacon transmitting in the MF or LF bandwidth, like a Non-Directional Beacon or commercial radio broadcast station.

Audio Control Panel

An Audio Control Panel or ACP is a kind of dashboard with buttons and knobs for the pilot to select the audio settings for reception and transition and for both communication and navigation radio frequencies.

Avionics Master Switch

As the name suggests, it is the main and only switch on an aircraft used to control the electrical systems and electronic equipment for navigation and communications.


This acronym stands for Aerodrome Weather Information Service, which is a system to collect, process, and transmit the most important weather data for air traffic control.


Base Leg

The flight path that has the aircraft descending in the direction of the landing of the runway.

Best Lift Over Drag Ratio

This is the highest value of lift to drag ratios for any airfoil, which is frequently referred to as ‘L over D Max’.

Black boxes

This is an informal name given to the Cockpit Voice Recorder (CVR ) and the Flight Data Recorders (FDR). However, the truth is that most of them are bright orange in order to be found easily in case of a crash. Apart from that, they are crash-resistant and equipped with beacons to make the work of locating them easier and quicker.

Blade Angle

In a propeller blade, the angle between the reference line and a plane perpendicular to the axis of rotation.

Bleed Air

The name was given to the compressed hot air that is produced by an aircraft engine during operation, which is then used for de-icing and heating the jet under high pressure.


Cabin Crew 

The name given to the team working for an airline to provide safety and comfort for the passengers during a flight, typically called flight attendants.

Calibrated Airspeed

Sometimes abbreviated with CAS he airspeed indicated in the instruments after correction for position and instrument error. It is equal to True Airspeed (TAS) at sea level. KCAS is an abbreviation used when Calibrated Airspeed is measured in knots. The term ‘reflected airspeed’ is used in some countries.

Calibrated altitude

Calibrated altitude is measured in respect to the Mean Sea Level, a constant value used in aviation and other applications.

Call sign

A call sign is a type of notation used by Air Traffic Control (ATC) to identify a specific flight. Call signs are usually different from flight numbers for two main reasons. First of all, for reasons of history or for easy understanding over the radio. Secondly, flights have been using alphanumeric call signs recently to avoid call sign confusion when flights with similar numbers may be talking to the same air traffic controller.


The level of convexity is measured on the wing of an aircraft.


This acronym stands for Ceiling and Visibility Unlimited and it refers to the ideal flying and visual meteorological conditions with visibility of 10 or more miles and a ceiling of at least 10,000 feet.


It refers to the height of cloud layers or similar weather phenomena that may block or reduce the visibility.


When a person or a company rents the entire aircraft instead of individual seats. It is common for business people to charter private jets.

Chord Line

It is an imaginary line on an airfoil that goes from the leading edge to the trailing edge of it.

Civil Aviation Authority

Usually abbreviated as CAA, it is the regulator of civil aviation in the UK since its foundation in 1972.

Civil Aviation Administration of China

Abbreviated as CAAC, the Civil Aviation Administration of China is the aviation regulator for the People’s Republic of China with headquarters in Beijing.


The word used air traffic control or the control tower grants permission for an aircraft to proceed with a particular action in controlled airspace with the purpose of preventing aircraft collisions.


This aviation term refers to the stage of a flight where the pilot increases the altitude trying to reach a specific level. It usually happens immediately after takeoff. However, it is also common for some routes to require what is known as “step climb”, which is an additional increase while flying on the designated route.


The part of the aircraft where the pilot and co-pilot seat and where the flight instruments and panels are located. This is normally at the front of the aircraft.

Cockpit voice recorder

Usually abbreviated CVR, the cockpit voice recorder saves the audio from the flight deck. This is generally achieved by recording the transmissions made by the flight crew via headsets and microphones sometimes placed around the cockpit. The main purpose of this recorders is to assist in investigators better understand what was happening inside the aircraft that may have resulted in an accident.

Codeshare flight

A flight where two different airlines show their own designater while referring to the same flight upon agreement. This is common when one airline operates the flight but partner airlines advertise the flight under their own code for marketing purposes, especially when the aircraft operator changes in connections until reaching the final destination. This simplifies the booking steps, as the passenger can take one single ticket while the flight involves two or more carriers.


It stands for Certificate of Airworthiness, the formal document issued by the National Aviation Authority (NAA) to certify that an aircraft is airworthy.

Common Traffic Advisory Frequency

Abbreviated with the acronym CTAF, it is the VHF radio frequency used for air-to-air communication in the US, Canada, and Australia where some airports close their control towers but keep the runways operative for some cargo operations.


It is a category of aircraft defined by the FAA as “limited to propeller-driven, multi-engine airplanes that have a seating configuration, excluding pilot seats, of 19 or less, and a maximum certificated takeoff weight of 19,000 pounds or less. The commuter category operation is limited to any maneuver incident to normal flying, stalls (except whip stalls), and steep turns, in which the angle of bank is not more than 60 degrees.”

Constant-Speed Propeller

A propeller with the capability to maintain a steady engine RPM by increasing and decreasing the blade pitch automatically.


A stream or a trail of condensed vapor that becomes visible in the air when the engines of an aircraft produce heat while flying at a high altitude.

Controlled Airspace

The class of airspace where ATC instructs pilots regarding aircraft movement and regulations. The main goal is to have controllers provide safe and efficient routes for all aircraft within the airspace. Also, this class of airspace is designed to create national security, which is why it requires specific qualifications for pilots and aircraft, so they can get clearance to enter the space.

Coordinated Universal Time

Abbreviated with the acronym UTC, this is the standard time zone used in aviation. It is the same as Greenwich Mean Time (GMT) and is regularly used in offsets such as UTC-1 and UTC+1.

Cost index

This is a number, generally between 0-100, which is entered into an aircraft’s Flight Management System (FMS) as a way of meeting aircraft operational requirements. This number comes from the calculation of fuel vs time-related costs. With an optimized cost index, it is possible to achieve the right balance between the cost of fuel and the cost of time.

Course Deviation Indicator

Abbreviated with the acronym CDI, it is a navigational instrument that shows whether the aircraft is to the right or left of the desired course. It is indicated by the needle in the VOR indicator, so whenever the aircraft is flying left of the selected course, the needle deflects proportionally to the right, and when the aircraft is flying right of the selected course, the needle deflects proportionally to the left.

Cross-Country Flight

Abbreviated as XC, it is a kind of flight that requires a special flight plan. The FAA requires this type of flight to be completed in order to obtain a Private Pilot License (PPL).


The kind of wind that blows in a direction that is not parallel to the flight path.



The acronym that is used for density altitude, which refers to the air density given as a height above mean sea level.


The name that is given to a forced landing that happens under no propulsion conditions due to engine or propeller malfunction.


The process of removing snow, ice, or frost that builds up on different parts of an aircraft, especially the wings. Normally, de-icing fluid is sprayed or heat applied to achieve the objective.

Delivery flight

It refers to the first flight of an aircraft from manufacturing to the airport or airfield selected by the operator acquiring it.


This aviation term is the opposite to climb, as it refers to the stage of a flight where the pilot decreases the altitude trying to reach a specific level. When the pilot begins descending to land at its destination, it is called “top of descent”. To guarantee oxygen levels for natural breathing during an emergency, especially when decompression occurs suddenly, the pilot will perform an emergency descent to below 10,000ft.


A word used internationally as a signal for an aircraft to be in danger and need immediate assistance.


An acronym that can be used to refer to Distance Measuring Equipment, a radio navigation technology used to measure the distance between the aircraft and a ground station, or Designated Mechanic Examiner, who is the person in charge of granting the corresponding certificates to pilots and aircraft maintenance technicians.


An aviation term that describes the kind of air that deflects downwards from an aircraft wing or a rotor blade on a helicopter, usually during take-off.

Downwind Leg

It refers to the flight path that goes parallel to the runway but in the opposite direction of the designated landing path.


A force that is parallel but opposite to the aircraft movement as it flies through the air. This is the force that causes resistance and that must be overcome by the propulsion power for the aircraft to be able to fly.



The acronym for the European Aviation Safety Agency, a European Union agency established in 2002 with the task of overseeing civil aviation safety and regulation.


The horizontal surface that controls aircraft pitch. It is usually articulated to the stabilizer.

Emergency overrun

The surface on the runway after the area for take-off. This surface is kept clear and it has the objective of reducing the damage to an aircraft if it is unable to take off and stop or stop after landing.


A name given to the tail of an aircraft, which provides stability during flight. The empennage consists of a rudder, a fin, and a stabilizer. This is also known as the tail assembly.

Equal time point

Abbreviated ETP, is a position on a route where the time taken to return to the departure point, is the same as the time required to reach the arrival point. It is not necessarily the midpoint (in distance) of the route because head or tailwinds can affect where exactly the equal time point will be.


The acronym for Estimated Time of Arrival. This is the time when arriving at the destination is expected and it is given in the destination’s local time.


The acronym for Estimated Time of Departure. Same as the ETA but for departure from the point of origin of the flight.


The acronym for Estimated Time en Route. This represents the amount of time expected to be spent traveling to a destination.


The European Organisation for the Safety of Air Navigation. It is based in Belgium and is the umbrella organization of national air navigation service providers in Europe.



The acronym for Federal Aviation Administration. This is the top authority regulating civil aviation in the United States.


This acronym stands for Federal Aviation Regulations, which are the FAA rules applied to civil aviation in the U.S.


Another acronym in the glossary. This time referring to Fixed-Base Operator, a kind of business or organization that operates at an airport providing aircraft services like maintenance, fueling, flight training, charter services, hangar services, and parking.

Ferry Flight

This is a type of flight that happens outside the regular flying operations of any carrier. These flights are usually carried out with the intention of returning an aircraft to the hub after maintenance or any other service, delivering a new aircraft to the organization acquiring it, moving an aircraft from one hub to another, or moving an aircraft to maintenance facilities.

Final Approach

A flight path that is taken to land on the runway at the end of a flight route.

Five by five

A phrase used to confirm that radio reception is loud and clear on a scale of 1 to 5.


Flaps are flat surfaces added to the edges of the wing that allow the pilot to adjust lift and drag by altering the curve of the wing enabling the aircraft to fly at lower speeds.


A required maneuver during landing to lower the descent rate that consists in pointing the nose of the aircraft upwards while descending towards the runway.


FLARM is a term formed from combining flight and alarm, and it is similar to ADS-B, but used in light aircraft, such as helicopters and gliders. It consumes a lot less power than traditional transponders, which is why is a favorite for gliders. FLARM equipment installation is regulated by EASA.

Flight data recorder

Flight Data Recorders, usually abbreviated FDR, are devices used to constantly record a variety of flight parameters. In case of an accident or a major incident, they work as a forensic tool to help investigators in understanding what happened. FDRs are regulated by the International Civil Aviation Organization (ICAO).

Flight Deck

This is another name given to the cockpit.

Flight Information Region / Upper Information Region

Flight Information Regions (FIR) and Upper Information Regions (UIR) are geographic areas under the responsibility of ATC. The size of these two areas is variable and its size depends on the country’s decision or the agreement of all the countries that the region covers. Oceanic airspace has its own classification as an Oceanic Information Region.

Flight level

Flight Level or FL is defined as the altitude of an aircraft at the standard air pressure, 1013.25 hPa (29.92 inHg). FL is expressed in hundreds of feet, for example, 42,000ft is expressed as FL420. FL is included in the flight plan so pilots can ensure vertical separation between aircraft is safe.

Flight number

This is the number applied by an airline in the schedule to identify a flight. Even numbers are usually applied to northbound and eastbound flights, and odd numbers are reserved for southbound and westbound flights. Larger flight numbers usually indicate a maintenance or positioning flight.

Flight Plan

Important information filed by pilots or dispatchers, usually before a flight that includes the exact route with the specific waypoints the flight will pass over, timing, and other relevant data.

Flying Dirty

An expression to describe an aircraft flying with landing gear, flaps, and other surfaces deployed in order to create drag.

First Officer

Abbreviated F/O, it is the person coming behind the captain in the hierarchy, or which is the same, the second in command of the aircraft.


This acronym stands for Flight Standards District Office which is a local authority overseen by the FAA.


This acronym stands for Flight Service Station, an organization providing information and services to pilots.

Fuel tankering

An expression used to describe the process of adding more fuel to the tank of an aircraft than the amount required for the flight in hand, usually to make it possible to complete the return flight as well. There are operational purposes behind this practice, such as reducing fuel costs, using higher quality fuel, or avoiding refueling for increased operational efficiency.


General Aviation

The division of civil aviation aircraft operations except for commercial air transport and aerial work.

Glass Cockpit

An aircraft that has its cockpit fully equipped with electronic, digital flight instrument displays, instead of analog-style gauges is called a glass cockpit aircraft.


The nickname was given to an aircraft autopilot system.


The flight pattern the pilot takes when a landing approach cannot be completed safely for any reason, and before trying to land again is called go-around. It usually involves a climb to a pre-specified altitude and holding point while awaiting further instructions from ATC.

Gross Weight

The total weight of an aircraft including people, cargo, fuel, etc.

Ground Effect

The increasing lift and decreasing drag resulting from the wings of the aircraft getting closer to the ground.


Putting an aircraft out of operation. This can happen for different reasons, but usually because it requires modifications or repairs in order to be fully compliant with airworthiness regulations. Good examples are the grounding of many aircraft in 2020 due to the pandemic, and the Boeing 737 MAX global grounding.

Ground Proximity Warning System

Sometimes expressed with the acronym GPWS, the Ground Proximity Warning System is designed to alert pilots they are flying to close to the ground and they are in danger of crashing into it.


It is the horizontal speed an aircraft measured when moving over the ground and in nautical miles per hour (Knots).



Expression used to describe when ATC transfers radar identification of an aircraft to another controller.


The process of requesting log-on or the “ping” operation in aeronautical satellite communication (SATCOM) systems usually to begin communications is known as the handshake.


Facilities in an airfield designed to hold aircraft for different purposes such as storing, maintenance, or assembly.


A term used by ATC to refer to aircraft with a maximum takeoff weight of 136 tonnes or more.

Holding pattern

A flight pattern in the form of ovals although a circular orbit is sometimes used as a faster substitute.



IAS stands for Indicated Airspeed, the air speed taken directly from the airspeed indicator without any corrections for temperature or pressure.


IATA stands for the International Air Transport Association, a trade organization composed by the airlines around the world which has an influence over the commercial aspects of flight.


ICAO stands for International Civil Aviation Organization, a specialized agency of the United Nations that supports aviation and navigation around the globe.


IFR stands for Instrument Flight Rules, the regulations for aircraft operations when using visual references is not possible for the pilots so they can fly by using instruments only. By following these rules, pilots can create IFR flight plans for various weather conditions.


IFSD stands for Integrated Standby Flight Display, a flight instrument which is commonly found in modern airliners and serves as a backup for primary instruments such as the altimeter, airspeed and attitude indicators.


ILS stands for Instrument Landing System, a system that uses radio waves to assist landings in IFR conditions.


IMC stands for Instrument Meterological Conditions, the weather conditions that describe a situation where pilots are required to operate with instruments only and following IFR.



An aircraft with one or more jet engines as the propulsion power.


Also known as an air bridge, a jetway is a movable and extendable structure that can be positioned to align with an aircraft door. It is normally used to connect the airport terminal with the aircraft, thus providing easy access to passengers and the cabin crew.


Also known as the control column, it is the main instrument to control an aircraft and is typically mounted on the ceiling or floor if the aircraft has a joystick instead of a yoke. Joysticks tend to be simpler to install since yokes are directly attached to the control surfaces like ailerons and flaps through cables and rods.



A measurement of speed that equals one nautical mile. Therefore, 1 knot = 1 nautical mile per hour = 6076 feet per hour.

Knots Calibrated Airspeed

Abbreviated KCAS, it is the airspeed measured in knots and corrected for instrument and position error

Knots Indicated Airspeed

Abbreviated KIAS, it is the airspeed of the aircraft in knots read directly from the airspeed indicator without corrections.

Knots True Airspeed

Abbreviated KTAS, it is the speed of the aircraft in knots relative to the air mass in which it is flying.


Landing gear

Defined as the undercarriage of an aircraft, it is the structure with wheels that supports the plane when on the ground and is used during taxi, take-off, and landing.

Level flight

The flight stage where the aircraft flies at the same altitude.


The aerodynamic force acting on an aircraft, opposite to its weight, and is mainly generated by the wings to overcome gravity so the aircraft can fly.

Lighter-than-air craft

Also known as LTA craft, it refers to other aerial objects like blimps, dirigibles, and free balloons that float.

Longitudinal axis

An imaginary line that goes horizontally from the head to tail of an aircraft through its center of gravity and is used for direction orientation.



The Mach number is defined as the ratio of true airspeed to the speed of sound at the altitude of a given flight. There are different Mach ranges. These are Subsonic, Transonic, Supersonic, Hypersonic, High-hypersonic, and re-entry speeds. Until now, all commercial flights are subsonic.

Magnetic Compass

The type of compass that provides the directional orientation of an aircraft according to the magnetic poles or the geomagnetic field.

Magnetic Deviation

The error produced by the unavoidable magnetic impact of aircraft materials.

Maneuvering Characteristics Augmentation System

Abbreviated with the acronym MCAS, this is a flight control system found on the Boeing 737 MAX. It was introduced to the 737 MAX to modify the pitch behavior of the Boeing 737 NG, providing NG-rated pilots with flight characteristic familiarity.

Maneuvering speed

A speed calculated by the aircraft manufacturer provided to the user to prevent exceeding the maximum load factor for the airplane.

Manufacturer’s serial number

Abbreviated MSN, a Manufacturer’s serial number is a unique code assigned to an aircraft, often prior to building it. It is also used to identify the parts that will make the aircraft.

Mean Sea Level

Abbreviated with the acronym MSL, it is the average height of the surface of the sea, used in aviation to measure vertical altitude.


Standardized by ICAO, a METAR is a specialized form of weather reporting used mainly in aviation. It follows a format specified by the regulator with the intention to make it easy to understand by any pilot around the world. It is delivered continuously and it represents the weather conditions at the moment rather than a forecast.

Mode S

This is a protocol of communication that allows an aircraft to communicate with secondary surveillance radars (SSR) and other systems through the transponder that is on-board.

Mountainous Terrain Escape Routes

The routes that allow a pilot to take an aircraft to an altitude below the Minimum Obstacle Clearance Altitude (MOCA) in case of emergency without any danger when flying over an area of high and mountainous terrain.

Multifunction Control Display Unit

Abbreviated MCDU, the Multifunction Control Display Unit is typically found in Airbus aircraft and consists of a screen and keypad which the crew uses as an interface with the aircraft FMS (Flight Management System).


Narrow-Body Aircraft

A small aircraft class that has a single-aisle inside and can carry 4 to 300 passengers.

National Transportation Safety Board

The NTSB is is the acronym used for this US government agency in charge of civilian transport accidents investigations. While their main focus is on aviation incidents and accidents, they also investigate marine, highway, rail, and pipeline incidents and accidents.


Non-directional beacon is a radio transmitter at a know location used as a navigation aid.

N number

The registration number on a US-registered plane. The letter N is the letter internationally used to identify a US plane.

North Atlantic Tracks

Officially known as North Atlantic Organized Track System or NAT-OTS are a specified set of routes that stretch Eastbound and Westbound across the North Atlantic. Aircraft require oceanic clearance to fly these routes, and they provide safety by keeping aircraft separated and considering ideal weather conditions.

Notice to Airmen

Abbreviated NOTAM, are written notices issued by aviation authorities to alert pilots of hazards or other specific circumstances that may affect their safe navigation over a given area.



The acronym for Outside Air Temperature, which is the temperature measured outside the aircraft.

Operating Limitations

Limits for an aircraft to operate safely. These are provided by the manufacturer and generally include airspeed, weight, pressure, and passenger and crew size.


An expression used when landing takes place beyond the runway.



The weight of what is carried by aircraft, including passengers, crew, cargo, etc.

Pilot in Command

Abbreviated PIC, it refers to the designated individual that is responsible for safe aircraft operations during flight.


The abbreviation of Pilot Report, a report a pilot gives to ATC describing actual weather conditions during a flight.


The movement of an aircraft, that sees the nose rising and the tail falling or vice versa.


This acronym stands for Pilot’s Operating Handbook, an aircraft flight manual containing pertinent safety information.

Primary Flight Display

Abbreviated PFD, it is the main screen used by pilots in aircraft containing an electronic flight instrument system, usually to read data relating to airspeed, altitude, heading, and vertical speed.

Primary radar

Primary radar outputs a radio signal and attempts to detect any reflection of that signal from an object, such as an airplane. It is common to avoid the word primary and just say radar when speaking about it.



The acronym for Quick Access Recorder, an airborne flight recorder that provides quick and easy access to raw flight data through a USB or cellular network.


QFE is an aeronautical “Q code” which provides a barometric altimeter setting that causes an altimeter to read zero when at the reference datum point of an airfield.


QNH is an aeronautical “Q code” which provides a barometric altimeter setting relating to airfield elevation above mean sea level. Standard QNH which is used when flying at Flight Levels is set to 1013.25hPa / 29.92inHg.


An aircraft type that has four wings with the same span.



The word used for the apron in the United States.

Registration or Tail Number

The unique number of each aircraft is assigned upon registration and frequently called the tail number. As it was described before, the N number is the registration or tail number in the United States.

Repositioning flight

Repositioning flights usually occur when an aircraft is out of place, either due to previous diversion or operational requirements.


The movement of an aircraft rotating along the longitudinal axis, which runs from the nose to the tail.


A control surface used to achieve the yaw movement properly.

Runway Visual Range

Abbreviated RVR, it is the horizontal distance that pilots can read by seeing surface markings or runway lights when positioned on the centerline of a runway.

Runway End Safety Area

Abbreviated RESA, it is an area located beyond the runway which is designated as a place for aircraft to enter in an attempt to minimize risk during unplanned occurrences, such as an overshoot.


Secondary radar

It is usually known as secondary surveillance radar because its main objective is to send out a signal to compatible aircraft, which then return a signal of their own with information about a flight, such as speed, altitude, heading, and registration.

Second in command

Abbreviated SIC, it refers to the designated individual to take over flight operations in case the PIC is not able to keep in operation.

Short Field

The name given to a runway that is shorter than usual and requires aircraft to minimize the amount of runway used when taking off or landing, thus posing a challenge for inexperienced pilots.


An aircraft movement that typically aligns with the lateral force of the wind and results in a sideways flow.


The sliding and outward pivoting movement of the aircraft that occurs as a result of a shallow turn.


The sliding and inward pivoting movement of the aircraft that occurs as a result of a steep turn.


A period of 15 minutes which is provided by ATC in order to limit the amount of aircraft using certain airspace.

Soft Field

An unpaved runway, typically requiring the aircraft to land on grass or dirt.


A unique four-digit transponder code given to an aircraft by ATC to allow for simple identification of an aircraft in a given region. There are a few significant squawk codes, which immediately get the attention of air traffic control. These are 7500: Hijack; 7600: Radio Failure; 7700: General Emergency


The condition affecting an aircraft when the angle of attack exceeds the aircraft limits so the air no longer flows easily over the airfoil, thus resulting in reduced lift.

Standard arrival route

Abbreviated STAR, it is a published instrument flight rule (IFR) routing that pilots use prior to transitioning to their chosen approach and landing profile.

Standard instrument departure route

Abbreviated SID, it is a published instrument flight rule (IFR) routing that pilots use directly after takeoff.

Standard Rate Turn

A turn that an aircraft makes at a rate of 3°/second or a 360° turn in two minutes.

Straight-and-Level Flight

Flying at a consistent heading and altitude.


Tactical Air Navigation System

Abbreviated TACAN, it is a UHF navigation system that provides aircraft with a distance and bearing.


It stands for Terminal Area Forecasts and are similar in format to METARs, but issued for future periods, hence the word forecasts in its name.


Another name for the apron, the paved area at an airport where aircraft park, fuel, load, and unload.


It stands for Traffic Collision Avoidance System, a system that allows aircraft to communicate if equipped with a compatible transponder in order to prevent a mid-air collision.


The area of a runway that indicates the beginning of it with specific marking.


A device that controls the amount of power coming from the engine.


A force generated by the aircraft engines to oppose drag in order to move forward.


A maneuver used to practice landing techniques by simply “touching” the runway and lifting the aircraft once more without coming to a full stop.


The device carried in an airplane and used to generate a code that is recognized on an ATC radar screen.


The track is the compass direction of the aircraft, denoted as 1-360. It represents the actual path or vector.

True Altitude

The vertical height of an aircraft above Mean Sea Level (MSL).


The acronym for tower.


The acronym for taxiway.


Upwind Leg

It refers to the flight path in an airport pattern that runs parallel to the runway in the same direction as the landing.

Useful Load

The weight of the contains that can be taken out of the aircraft such as fuel, passengers, cargo, pilots, etc.


Vertical Speed

It refers to the rate at which a plane is ascending or descending.


It stands for Visual Flight Rules, regulations that define aircraft operations when pilots are able to operate using visual references, or the opposite of IFR.


It stands for Visual Meteorological Conditions, the minimum requirements for VFR flight to be possible before turning to IFR.


It stands for Very High-Frequency Omni-Directional Range, a short-range radio navigation beacon. A network of VORs can be used by pilots to determine their position and course.


This acronym stands for Vertical Speed Indicator, and it is an instrument that displays the climb or descent rate in feet-per-minute by sensing the change in atmospheric pressure. It is also known as a variometer.



A steering method used by pilots in a hang glider or paraglider where the pilots use their weight to steer the craft, pushing against a triangular control bar that’s attached to the wing structure.

Wide-Body Aircraft

An aircraft with two aisles inside. The typical fuselage diameter is 16 to 20 feet.

Wind Shear

An abrupt change in horizontal or vertical wind direction.


An abbreviation for weather.



An abbreviation for cross-country.



The movement of an aircraft around the vertical axis, characterized by the nose moving side-to-side.


The input device a pilot uses to control the pitch and roll of an aircraft which is similar to a car steering wheel.


Zulu Time

Pilots file all flight plans in Zulu Time, a term for Universal Coordinated Time (UTC), also known as Greenwich Mean Time.

There you have it. This is probably the most comprehensive glossary you will find about the terms used across the aviation industry. Feel free to bookmark or add this page to your favorites so you can come back and check it any time you need it.