Detailed List of Common Aviation Terms and Their Meanings (From A to Z) Part 2

Common Aviation Terms From A-Z and Their Meanings Part 2

In a previous post, I explained the means of several common aviation terms. However, as you know, aviation lingo is almost inexhaustible. Here are some more aviation terms and acronyms and their meanings.

You can add this article to your bookmarks too, so whenever a term foreign to you comes up, you can easily check it out.

NB: Some of the terms may have slightly different names for different aircraft companies. I try as much as possible to specify them within the article.

A

• A/P: Autopilot which is also short for the automatic pilot. It is an aircraft system that provides commands to the flight controls in place of the pilot, ensuring a well-maintained flight path.
• ACARS: Aircraft Communication Addressing and Reporting System. It is a data link system used for communication between aircraft and airline operation centers on the ground.
• ACE: Actuator Control Electronics. It is the component of Fly-By-Wire (FBW) systems that converts analog signals to digital signals and vice versa.
• ADF: Automatic Direction Finder. One of the navigation systems used in aircraft. It identifies the bearing of the aircraft relative to a ground-based radio beacon.
• ADIRS: Air Data and Inertial Reference System. It is a system that records and provides data such as airspeed, angle of attack, acceleration, and so on to navigation and flight control systems of aircraft.
• ADIRU: Air Data And Inertial Reference Unit. There are multiple ADIRUs in an ADIRS.
• ADM: Air Data Module. It is the core building block of an ADIRS.
• AFDC: Automatic Flight Director Computer. There are multiple AFDCs in the AFDS which receive and process important air data used to fly the aircraft.
• AFDS: Automatic Flight Director System. The name of the auto-flight system in Boeing aircraft.
• Airframe: the skeletal structure of an aircraft.
• AIMS: Airplane Information Management System. It comprises all the flight instruments which display the required information for flying the plane.
• Airbus: A European aerospace company and one of the top passenger aircraft manufacturers in the world.
• APU: Auxiliary Power Unit. It drives a single generator that serves as a backup source of AC electrical power in aircraft. It also provides bleed air.
• Anhedral: used to refer to aircraft wings that slant downwards at an angle to the horizontal plane. It is also called the negative dihedral.
• ARINC: Aeronautical Radio, Incorporated. A transport company that provides various technologies used in aviation and avionics. ARINC 429 and ARINC 629 are some standard avionics data buses used in aircraft.
• Aspect ratio (of the wing): the ratio of the square of the wingspan to the wing area.
• ATSU: Air Traffic Service Unit. It is a computer that performs ATC communication management functions in Airbus aircraft.
• Autoland: it is the feature of the Autopilot system that enables the plane to land itself.
• Auto-throttle: it is the part of an auto-flight system that acts to increase or reduce thrust from the engines as needed during different phases of flight.
• Avgas: Aviation gasoline.

B

• BAP: Bank Angle Protection. A flight envelope protection mode of an FBW system ensures the plane does not exceed a certain bank angle.
• Boeing: An American aerospace company, and one of the top passenger aircraft manufacturers in the world.
• Boundary layer: the area between a body’s surface and the region of free-stream velocity
• BSCU: Braking/Steering Control Unit. It processes commands for the braking system and nose wheel landing gear of an aircraft.

C

• CAT: category. As in ILS CAT I, CAT II, CAT III.
• CFRP: Carbon Fibre Reinforced Polymer. A lightweight composite material used in the construction of modern aircraft. It is preferred because it offers very high strength with a relatively low density.
• CPDLC: Controller Pilot Data Link Communication. It is a data link system used solely for communication between pilots and ATC on the ground.
• Cone of confusion/ ambiguity: this is a cone region wherein the signals of the VOR drastically depreciate in quality. In this cone, the indicator on the cockpit display will fluctuate erratically, not allowing for valid readings.
• CSD: Constant Speed Drive. It is a hydromechanical unit that is responsible for producing a constant speed supply for the generator from the engine which produces different frequencies/speeds. It is integrated with the generator of an IDG.

D

• DDRMI: Digital Distance Radio Magnetic Indicator. It shows the bearing of the aircraft in the cockpit of Airbus aircraft.
• Decision height: the altitude at which the pilot decides whether to go around or commence landing. It is also called the minimum altitude.
• Dihedral: used to refer to aircraft wings that slant upwards at an angle to the horizontal plane.
• Dutch roll: an unstable oscillatory combination of roll and yaw movements of an aircraft.

E

• ELACS: Elevator Aileron Computer System. The computers that control the elevators and ailerons in Airbus aircraft.

F

• FAC: Flight Augmentation Computer. It controls the movement of the rudder, rudder trim, and yaw damper in Airbus aircraft.
• FD: Flight Director. The part of a Boeing auto-flight system that gives guidance to the system. It essentially takes the place of the pilot.
• FDU: Fire Detection Unit.
• FIR: Flight Information Region. This is a defined airspace area in which a flight information service and alerting service are provided. Countries responsible for specific FIRs are designated by ICAO.
• FMCF: Flight Management Computing Function.
• FMCS: Flight Management Computing System. It is the system that provides data (collected from various navigation systems)that allows the FD or pilot to guide the aircraft between waypoints or intercept a course. The FMCS also has the ability to create phantom waypoints.
• Flight cycle: the flight operation of an aircraft from take-off to landing. OEMs usually rate an aircraft or engine’s life in terms of flight cycles.
• FSEU: flap/slat electronic unit. It processes commands given to the flaps and slats from the pilot.

G

• Glideslope: a radio beam path projected by the ILS which provides vertical guidance for landing. The aircraft is supposed to align with the glide path at the center of the glideslope.
• GCU: General Control Unit. It controls the frequency and voltage outputs of the IDGs and APU generators.
• GPCU: Ground Power Control Unit. It controls the external ground power connection which is used to power some parts of the aircraft’s electrical network while the aircraft is on the ground.
• GPS: Global Positioning System. One of the navigation systems used in aircraft.

H

• HLCS: High Lift Control System, a term used to refer to secondary flight control systems in some Boeing aircraft.
• Hypersonic: used to refer to extremely high speeds, well above the speed of sound. It applies to aircraft speeds with Mach numbers 5.0 – 10.0.

I

• IATA: International Air Transport Association. It is the global trade association of airlines.
• IDG: Integrated Drive Generator. The generator assembly is driven by an aircraft engine through the latter’s accessory gearbox. It is the main source of AC electrical power for an aircraft.
• INS: Inertial Navigation System. It is a navigation system used in aircraft that involves the use of gyroscopes.
• IRS: Inertial Reference System. In aircraft where the INS setup is not only used for navigation, it is instead called the IRS.

L

• Localizer: the extended centreline of the runway created by the ILS which provides lateral guidance for landing.
• Longerons: structural reinforcements for the skin of aircraft.
• LNAV: Lateral Navigation. It is the auto-flight mode that concerns navigation in the lateral path.
• LRU: Line Replaceable Unit. This is a modular component of an aircraft that can easily be removed or replaced. Aircraft systems have multiple LRUS.
• LVDT: Linear Variable Differential Transformer. It converts the linear movement of the pilot command inputs or controls surfaces to electrical signals.

M

• MCDU: Multifunction Control Display Unit. It is used both for displaying alert/advice memos and flight information, mostly in Airbus aircraft. Red light indicates fail mode while white lights simply call the attention of the pilot to other systems.
• MCP: Mode Control Panel. It contains the switches that are used to control the various Autopilot modes.

N

• Nacelle: the case that houses the aircraft engine assembly.
• NASA: National Aeronautics and Space Administration.
• ND: Navigation Display. It displays the lateral navigation status of the aircraft. It is often combined with the PFD in modern aircraft.

P

• PBN: Performance-Based Navigation. It checks the performance of navigation aids in line with the RNP standard.
• PCU: Power Control Unit. It produces surface signals that are used to drive the flight controls in an FBW system. It comprises hydraulic actuators, servo-actuators, and feedback transducers.
• PFC: Primary Flight Computer. It is the central computation unit of Boeing FBW systems.
• PFCS: Primary Flight Control System, a term used in Boeing aircraft.
• Planform: the shape of the aircraft wing and fuselage when viewed on a horizontal plane.

R

• RA: Radio Altitude. The altitude of the aircraft according to the radio altimeter.
• Radome: a protective cover for the antenna of radar systems, usually located in the nosecone of aircraft. They are spherical shells made up of panels.
• RAT: Ram Air Turbine. It is a small windmill-like component in the belly fairing of an aircraft that is used as a backup power source for the aircraft’s electrical system. It is usually the last resort before the batteries.
• Reynold’s number: the ratio of the inertial forces of a fluid to its viscous forces. It is used to determine whether the boundary layer flow is turbulent or laminar.
• Rib: an aerofoil-shaped structural component that runs chord-wise of the wing.
• RNAV: Area Navigation. It is a navigation method that allows an aircraft to fly on its desired flight path within the limits of its own isolated navigation aids and/or navigation aids that work with ground stations. It is not a navigation aid on its own.
• RNP: Required Navigation Performance. The RNP standard must be met for 95% of flight time in both the lateral and longitudinal axes. RNP standards differ for different flight applications or locations.
• RVDT: Rotary Variable Differential Transformer. It converts the angular displacement of the aircraft yoke(s) to a linear output signal which is then sent to the flight controls.
• RVR: Runway Visual Range. It is the horizontal distance over which a pilot on the centreline of a runway can see the runway surface markings or high-intensity runway lights.

S

• SDCU: Smoke Detection Control Unit.
• SEC: Spoiler Elevator Computer. The computers that control the spoilers and elevators in Airbus aircraft.
• Sharklet: an Airbus term for the blended winglet design.
• Shockwave: a build-up of pressure waves formed at transonic and supersonic speeds. Shockwaves result in very turbulent airflow around the aircraft.
• SID: Standard Instrument Departure. This is the designated Instrument Flight Rule (IFR) departure route that links a runway with a significant point en route.
• Side-stick: it is equivalent to the yoke in some aircraft as it receives pilot command inputs for the elevators and ailerons.
• Slats: they are also leading-edge flaps. They lift augmentation devices located at the leading edges of some aircraft wings.
• Sonic boom: an explosive sound produced as aircraft move at supersonic speeds. It can cause significant damage to structures it makes contact with.
• Spar: a beam that runs span-wise of the wing.
• SRM: Structural Repair Manual. A manual containing instructions for the repair of aircraft structures is provided by the manufacturer.
• STAR: Standard Terminal Arrival. This is a designated IFR arrival route that links a significant point en route to a point where Instrument Approach Procedures can begin.
• STOL: Short Take-off and Landing. Used to refer to aircraft that can take off and land with very little runway required.
• Subsonic: used to refer to speeds below the local speed of sound. It applies to aircraft speeds with Mach numbers up to 0.7.
• Supersonic: used to refer to a speed of an aircraft that is greater than the local speed of sound. It applies to aircraft speeds with Mach numbers 1.2 – 5.0.

T

• TO/GA: take-off/ go around. These are switches located on the thrust levers.
• TMCS: Thrust Management Computing System. It processes the auto-throttle commands.
• Transonic: used to refer to speeds approaching or near the local speed of sound. It applies to aircraft speeds with Mach numbers 0.7- 1.2. At transonic speeds, both subsonic and supersonic speeds are present in localized regions around the aircraft.
• Triple Seven “777”: Commonly used to refer to the Boeing 777 aircraft, an airliner for long-haul flights.
• TSFC: Thrust Specific Fuel Consumption. It is one of the most common parameters used to determine the fuel efficiency of an aircraft.

V

• V/S: vertical speed.
• Vortex: It is the whirl-like motion of air that is formed around the wing tips as the wing generates lift. It forms turbulent airflow and its plural form is “vortices”.
• Vortex generator: it is a wingtip device that creates vortices to attenuate shockwaves, thereby reducing shock drag.
• VNAV: vertical navigation. It is the auto-flight mode that concerns navigation in the vertical path.
• VTOL: Vertical Take-Off and Landing. Used to refer to aircraft that can take off and land vertically without requiring a runway. Such aircraft are able to take off instantly, like helicopters.

W

• Waypoint: this is a specified geographical location that is used to mark out the flight path of an aircraft, sort of like junctions for cars driving on the road. However, waypoints have specific geographic coordinates and are not actually visible points.
• Wind tunnel: a laboratory device that is used for testing the flow dynamics around a body such as turbine blades, aerofoils, and so on by simulating uniform flow conditions in the test section in which the body is kept.

Y

• Yaw damper: a part of aircraft flight control systems that acts to counter or reduce the effect of Dutch Roll.

Conclusion

The above Common Aviation Terms add to the previously-listed aviation terms. Use the comment section to give us feedback regarding your opinion on this topic.