A

• ACARS: Aircraft Communications Addressing and Reporting System.
• ACAS
  Airborne Collision Avoidance System
  An airborne collision avoidance system is an aircraft system that operates independently of ground-based equipment and air traffic control in warning pilots of the presence of other aircraft that may present a threat of collision. If the risk of collision is imminent, the system indicates a...
  
  : Airborne Collision Avoidance System
  Airborne Collision Avoidance System
  An airborne collision avoidance system is an aircraft system that operates independently of ground-based equipment and air traffic control in warning pilots of the presence of other aircraft that may present a threat of collision. If the risk of collision is imminent, the system indicates a...
  
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• ACP: Audio Control Panel.
• ACS: Audio Control System.
• ADAHRS: Air Data and Attitude Heading Reference System.
• ADC
  Air data computer
  An air data computer is an essential avionics component found in modern glass cockpits. This computer, rather than individual instruments, can determine the calibrated airspeed, Mach number, altitude, and altitude trend from input data from sensors such as an aircraft's pitot-static system,...
  
  : Air Data Computer
  Air data computer
  An air data computer is an essential avionics component found in modern glass cockpits. This computer, rather than individual instruments, can determine the calibrated airspeed, Mach number, altitude, and altitude trend from input data from sensors such as an aircraft's pitot-static system,...
  
  .
• ADF: Automatic Direction Finder.
• ADI: Attitude Director Indicator.
• ADIRS: Air Data Inertial Reference System.
• ADIRU: Air Data Inertial Reference Unit
  Air Data Inertial Reference Unit
  An Air Data Inertial Reference Unit is a key component of the integrated Air Data Inertial Reference System , that supplies air data and inertial reference information to the pilots' Electronic Flight Instrument System displays as well as other systems on the aircraft such as the engines,...
  
  .
• ADM: Air Data Module
  Air data module
  Air Data Module is a component of the navigation system on fly-by-wire aircraft, such as Airbus A320 or later Airbus. Each unit converts pneumatic information from a Pitot tube or a static port in to numerical information which is sent on a data bus...
  
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• ADS: Either; Automatic Dependant Surveillance or Air Data System.
• ADS-A: Automatic Dependant Surveillance /Address.
• ADS-B: Automatic Dependant Surveillance-Broadcast
  Automatic dependent surveillance-broadcast
  Automatic Dependent Surveillance-Broadcast is a surveillance technology for tracking aircraft as part of the Next Generation Air Transportation System ...
  
  .
• AFCS: Automatic Flight Control System.
• AFD: Autopilot Flight Director.
• AFDC: Autopilot Flight Director Computer.
• AFDS: Autopilot Flight Director System.
• AFIS: Either; Automatic Flight Information Service or Airborne Flight Information System.
• AGACS: Automatic Ground-Air Communications System, is also known as ATCSS or data link
  Data link
  In telecommunication a data link is the means of connecting one location to another for the purpose of transmitting and receiving information. It can also refer to a set of electronics assemblies, consisting of a transmitter and a receiver and the interconnecting data telecommunication circuit...
  
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• AGC
  Automatic gain control
  Automatic gain control is an adaptive system found in many electronic devices. The average output signal level is fed back to adjust the gain to an appropriate level for a range of input signal levels...
  
  : Automatic Gain Control
  Automatic gain control
  Automatic gain control is an adaptive system found in many electronic devices. The average output signal level is fed back to adjust the gain to an appropriate level for a range of input signal levels...
  
  .
• AHC: Attitude Heading Control.
• AHRS: Attitude and Heading Reference Systems
  Attitude and Heading Reference Systems
  An attitude heading reference system consists of sensors on three axes that provide heading, attitude and yaw information for aircraft. They are designed to replace traditional mechanical gyroscopic flight instruments and provide superior reliability and accuracy.AHRS consist of either solid-state...
  
  .
• ALC: Automatic Level Control.
• ALT: Either; Altimeter
  Altimeter
  An altimeter is an instrument used to measure the altitude of an object above a fixed level. The measurement of altitude is called altimetry, which is related to the term bathymetry, the measurement of depth underwater.-Pressure altimeter:...
  
   or Altitude
  Altitude
  Altitude or height is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context...
  
  .
• ALT Hold: Altitude Hold Mode.
• ALTS: Altitude Select.
• AMLCD: Active Matrix Liquid Crystal Display.
• ANC: Active Noise Cancellation.
• ANN: Annunciator- caution warning system normally containing visual and audio alerts to the pilot.
• ANR
  Active noise control
  Active noise control is a method for reducing unwanted sound.- Explanation :...
  
  : Active Noise Reduction.
• ANT: Antenna
  Antenna (radio)
  An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...
  
  .
• A/P: Autopilot
  Autopilot
  An autopilot is a mechanical, electrical, or hydraulic system used to guide a vehicle without assistance from a human being. An autopilot can refer specifically to aircraft, self-steering gear for boats, or auto guidance of space craft and missiles...
  
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• APC: Autopilot Computer.
• APS: Autopilot System.
• APU
  Auxiliary power unit
  An auxiliary power unit is a device on a vehicle that provides energy for functions other than propulsion. They are commonly found on large aircraft, as well as some large land vehicles.-Function:...
  
  : Auxiliary Power Unit
  Auxiliary power unit
  An auxiliary power unit is a device on a vehicle that provides energy for functions other than propulsion. They are commonly found on large aircraft, as well as some large land vehicles.-Function:...
  
  
• ASD: Aircraft Situation Display.
• ASDL: Aeronautical Satellite Data Link.
• ASR
  Airport Surveillance Radar
  An airport surveillance radar is a radar system used at airports to detect and display the position of aircraft in the terminal area.-Digital Airport Surveillance Radar :...
  
  : Airport Surveillance Radar
  Airport Surveillance Radar
  An airport surveillance radar is a radar system used at airports to detect and display the position of aircraft in the terminal area.-Digital Airport Surveillance Radar :...
  
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• ARINC
  ARINC
  Aeronautical Radio, Incorporated , established in 1929, is a major provider of transport communications and systems engineering solutions for eight industries: aviation, airports, defense, government, healthcare, networks, security, and transportation...
  
  : Aeronautical Radio, Incorporated (ARINC)
• ASU: Avionics Switching Unit.
• ATCRBS: Air Traffic Control Radar Beacon System
  Air Traffic Control Radar Beacon System
  The air traffic control radar beacon system is a system used in air traffic control to enhance surveillance radar monitoring and separation of air traffic. ATCRBS assists ATC surveillance radars by acquiring information about the aircraft being monitored, and providing this information to the...
  
  .
• ATCSS: Air Traffic Control Signaling System.
• ATI
  Ati
  As a word, Ati may refer to:* Ati, a town in Chad* Ati, a Negrito ethnic group in the Philippines* Ati-Atihan Festival, an annual celebration held in the Philippines* Ati, a queen of the fabled Land of Punt in Africa...
  
  : Unit of measure for instrument size, a standard 3¨û cutout is a 3ATI.
• ATM
  ATM
  -In science and technology:*Adobe Type Manager, typeface management software from Adobe Systems Allocated*Air traffic management, synonym for air traffic control*Alternating Turing machine, model of computation used in theoretical computer science...
  
  : Air Traffic Management.
• Avionics
  Avionics
  Avionics are electronic systems used on aircraft, artificial satellites and spacecraft.Avionic systems include communications, navigation, the display and management of multiple systems and the hundreds of systems that are fitted to aircraft to meet individual roles...
  
  : Aviation electronics.
• AWG: American Wire Gauge
  American wire gauge
  American wire gauge , also known as the Brown & Sharpe wire gauge, is a standardized wire gauge system used since 1857 predominantly in the United States and Canada for the diameters of round, solid, nonferrous, electrically conducting wire...
  
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B

• B RNAV: Basic Area Navigation.
• BARO
  Baro
  Baro is a city in central Nigeria.- Transport :It is located approximately 400 miles up the Niger River at the limit of river navigation, subject to dredging. It is also the terminus of a railway branchline connected to the Nigerian railway system.- External links :*...
  
  : Barometric indication, setting or pressure.
• BCRS: Back Course.
• BDI: Bearing Distance Indicator.
• BGAN: Broadcast Global Area Network.

C

• CAI: Caution Annunciator Indicator.
• CAT I: Operational performance Category 1.
• CAT I Enhanced. Allows for lower minimums than CAT I in some cases to CAT 2 minimums.
• CAT II: Operational performance Category II.
• CAT IIIa: Operational performance Category IIIa.
• CAT IIIb: Operational performance Category IIIb.
• CAT IIIc: Operational performance Category IIIc.
• CODEC
  Codec
  A codec is a device or computer program capable of encoding or decoding a digital data stream or signal. The word codec is a portmanteau of "compressor-decompressor" or, more commonly, "coder-decoder"...
  
  : Coder/Decoder.
• CDI: Course Deviation Indicator
  Course deviation indicator
  Course Deviation Indicator is an avionics instrument used in aircraft navigation to determine an aircraft's lateral position in relation to a track. If the location of the aircraft is to the left of course, the needle deflects to the right, and vice versa.-Use:The instrument shows the direction...
  
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• CFIT: Controlled Flight Into Terrain
  Controlled flight into terrain
  Controlled flight into terrain describes an accident in which an airworthy aircraft, under pilot control, is unintentionally flown into the ground, a mountain, water, or an obstacle. The term was coined by engineers at Boeing in the late 1970s...
  
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• COMM
  Comm
  The comm command in the Unix family of computer operating systems is a utility that is used to compare two files for common and distinct lines. comm is specified in the POSIX standard. It has been widely available on Unix-like operating systems since the mid to late 1980s.-Usage:comm reads two...
  
   or COM: Communications Receiver
  Communications receiver
  A communications receiver is a type of radio receiver used as a component of a radio communication link.-Features:Commercial communications receivers are characterised by high stability and reliability of performance, and are generally adapted for remote control and monitoring...
  
  .
• CNS: Communication, Navigation, Surveillance.
• CNS/ATM: Communication, Navigation, Surveillance/Air Traffic Management.
• CPDLC: Controller-Pilot Data Link Communication.
• CPS: Cycles Per Second.
• CRT: Cathode Ray Tube
  Cathode ray tube
  The cathode ray tube is a vacuum tube containing an electron gun and a fluorescent screen used to view images. It has a means to accelerate and deflect the electron beam onto the fluorescent screen to create the images. The image may represent electrical waveforms , pictures , radar targets and...
  
  .
• CTAF: Common Traffic Advisory Frequency
  Common Traffic Advisory Frequency
  Common Traffic Advisory Frequency , is the name given to the VHF radio frequency used for air-to-air communication at U.S., Canadian and Australian non-towered airports....
  
  .
• CV/DFDR: Cockpit Voice and Digital Flight Data Recorder.
• CVR: Cockpit Voice Recorder
  Cockpit voice recorder
  A cockpit voice recorder , often referred to as a "black box", is a flight recorder used to record the audio environment in the flight deck of an aircraft for the purpose of investigation of accidents and incidents...
  
  .
• CWS: Control Wheel Steering.

D

• DA: Drift Angle.
• DG: Directional Gyroscope.
• DGPS: Differential Global Positioning System.
• DH: Decision Height.
• DME: Distance Measuring Equipment
  Distance Measuring Equipment
  Distance measuring equipment is a transponder-based radio navigation technology that measures distance by timing the propagation delay of VHF or UHF radio signals....
  
  .
• DNC: Direct Noise Canceling.
• DP: Departure Procedures.
• DSP: Digital Signal Processing
  Digital signal processing
  Digital signal processing is concerned with the representation of discrete time signals by a sequence of numbers or symbols and the processing of these signals. Digital signal processing and analog signal processing are subfields of signal processing...
  
  .
• DUAT
  Duat
  In Egyptian mythology, Duat is the underworld. The Duat is a vast area under the Earth, connected with Nun, the waters of the primordial abyss. The Duat is the realm of the god Osiris and the residence of other gods and supernatural beings...
  
  : Direct User Access Terminal.

E

• EADI: Electronic Attitude Director Indicator.
• EFD: Electronic Flight Display.
• EFIS: Electronic Flight Instrument System
  Electronic Flight Instrument System
  An electronic flight instrument system is a flight deck instrument display system in which the display technology used is electronic rather than electromechanical. EFIS normally consists of a primary flight display , multi-function display and engine indicating and crew alerting system display...
  
  .
• EGPWS: Enhanced Ground Proximity Warning System.
• EGT: Exhaust Gas Temperature.
• EHSI: Electronic Horizontal Situation Indicator.
• EICAS
  EICAS
  Engine Indicating and Crew Alerting System is an integrated system used in modern aircraft to provide aircraft crew with aircraft engines and other systems instrumentation and crew annunciations...
  
  : Engine Indication Crew Alerting System.
• ELT: Emergency Locator Transmitter.
• ENC: Electronic Noise Canceling.
• ENR: Electronic Noise Reduction.
• EPR: Engine Pressure Ratio.
• ETOP: Extended Range Twin Engine Operation.

F

• FADEC
  FADEC
  Full Authority Digital Engine Control is a system consisting of a digital computer, called an electronic engine controller or engine control unit , and its related accessories that control all aspects of aircraft engine performance...
  
  : Full Authority Digital Engine Control.
• FAT: Free Air Temperature.
• FDRS: Flight Data Recorder System.
• FDU: Flux Detector Unit.
• FF: Fuel Flow.
• FIS-B: Flight Information Services- Broadcast.
• FLIR: Forward Looking Infra-Red.
• FLTA: Forward Looking Terrain Avoidance.
• FMS: Flight Management System
  Flight management system
  A flight management system is a fundamental part of a modern airliner's avionics. An FMS is a specialized computer system that automates a wide variety of in-flight tasks, reducing the workload on the flight crew to the point that modern aircraft no longer carry flight engineers or navigators. A...
  
  .
• FREQ
  Freq
  Freq is a 1985 album by English singer and musician Robert Calvert.It was recorded during the time of the UK miners' strike and in between the songs it features snippets of field recordings by Calvert with miners on a picket line, with Calvert displaying his sympathy for their cause.The lyrics...
  
  : Frequency
  Frequency
  Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...
  
  .
• FSS: Flight service station
  Flight service station
  A Flight Service Station is an air traffic facility that provides information and services to aircraft pilots before, during, and after flights, but unlike air traffic control , is not responsible for giving instructions or clearances or providing separation...
  
  
• FWS: Flight Warning System.
• FYDS: Flight director
  Flight director (aviation)
  In aviation, a flight director is a navigational aid that is overlaid on the attitude indicator that shows the pilot of an aircraft the attitude required to follow a certain trajectory.-Description:...
  
  / Yaw Damper System.

G

• GCAS: Ground Collision Avoidance System.
• GCU: Generator Control Unit.
• GDOP: Geometric Dilution Of Precision.
• GGS: Global positioning system Ground Station.
• GHz: Gigahertz.
• GLNS: GPS Landing and Navigation System.
• GLNU: GPS Landing and Navigation Unit.
• GLONASS
  GLONASS
  GLONASS , acronym for Globalnaya navigatsionnaya sputnikovaya sistema or Global Navigation Satellite System, is a radio-based satellite navigation system operated for the Russian government by the Russian Space Forces...
  
  : Global Navigation Satellite System
  Global Navigation Satellite System
  A satellite navigation or SAT NAV system is a system of satellites that provide autonomous geo-spatial positioning with global coverage. It allows small electronic receivers to determine their location to within a few metres using time signals transmitted along a line-of-sight by radio from...
  
  .
• GLS: GPS Landing System.
• GLU: GPS Landing Unit.
• GND: Ground.
• GNSS: Global Navigation Satellite System
  Global Navigation Satellite System
  A satellite navigation or SAT NAV system is a system of satellites that provide autonomous geo-spatial positioning with global coverage. It allows small electronic receivers to determine their location to within a few metres using time signals transmitted along a line-of-sight by radio from...
  
  .
• GMT: Greenwich Mean Time
  Greenwich Mean Time
  Greenwich Mean Time is a term originally referring to mean solar time at the Royal Observatory in Greenwich, London. It is arguably the same as Coordinated Universal Time and when this is viewed as a time zone the name Greenwich Mean Time is especially used by bodies connected with the United...
  
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• GPS: Global Positioning Satellite or Global Positioning System
  Global Positioning System
  The Global Positioning System is a space-based global navigation satellite system that provides location and time information in all weather, anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites...
  
  .
• GPWC: Ground Proximity Warning Computer.
• GPWS: Ground Proximity Warning System
  Ground Proximity Warning System
  A ground proximity warning system is a system designed to alert pilots if their aircraft is in immediate danger of flying into the ground or an obstacle. The United States Federal Aviation Administration defines GPWS as a type of terrain awareness warning system...
  
  .

H

• HDG: Heading.
• HDG SEL: Heading Select.
• HDOP: Horizontal Dilution Of Precision.
• HF: High Frequency
  High frequency
  High frequency radio frequencies are between 3 and 30 MHz. Also known as the decameter band or decameter wave as the wavelengths range from one to ten decameters . Frequencies immediately below HF are denoted Medium-frequency , and the next higher frequencies are known as Very high frequency...
  
  .
• HHLD: Heading Hold.
• HSD: High Speed Data.
• HSI: Horizontal Situation Indicator
  Horizontal Situation Indicator
  The horizontal situation indicator is an aircraft instrument normally mounted below the artificial horizon in place of a conventional heading indicator. It combines a heading indicator with a VOR/ILS display, reducing pilot workload by lessening the number of elements in the pilot's instrument...
  
  .
• HSL: Heading Select.
• HUD: Head-Up Display
  Head-Up Display
  A head-up display or heads-up display is any transparent display that presents data without requiring users to look away from their usual viewpoints...
  
  .
• HMD: Helmet Mounted Display
  Helmet mounted display
  A helmet mounted display is a device used in some modern aircraft, especially combat aircraft. HMDs project information similar to that of head-up displays on an aircrew’s visor or reticle, thereby allowing him to obtain situational awareness and/or cue weapons systems to the direction his head...
  
  .

I

• IAS: Indicated Airspeed
  Indicated airspeed
  Indicated airspeed is the airspeed read directly from the airspeed indicator on an aircraft, driven by the pitot-static system. IAS is directly related to calibrated airspeed , which is the IAS corrected for instrument and installation errors....
  
  .
• ID: Identify/Identification or identifier.
• IDENT: Identify/Identifier
  Identifier
  An identifier is a name that identifies either a unique object or a unique class of objects, where the "object" or class may be an idea, physical [countable] object , or physical [noncountable] substance...
  
  .
• IDS: Information Display System or Integrated Display System.
• IFE: In-Flight Entertainment
  In-flight Entertainment
  In-flight entertainment refers to the entertainment available to aircraft passengers during a flight. In 1936, the airship Hindenburg offered passengers a piano, lounge, dining room, smoking room, and bar during the 2½ day flight between Europe and America...
  
  .
• IFR: Instrument Flight Regulations.
• ILS: Instrument Landing System
  Instrument Landing System
  An instrument landing system is a ground-based instrument approach system that provides precision guidance to an aircraft approaching and landing on a runway, using a combination of radio signals and, in many cases, high-intensity lighting arrays to enable a safe landing during instrument...
  
  .
• IMC: Instrument Meteorological Conditions
  Instrument meteorological conditions
  Instrument meteorological conditions is an aviation flight category that describes weather conditions that require pilots to fly primarily by reference to instruments, and therefore under Instrument Flight Rules , rather than by outside visual references under Visual Flight Rules . Typically, this...
  
  .
• InHg: Inch of Mercury
  Inch of mercury
  Inches of mercury, ' is a unit of measurement for pressure. It is still widely used for barometric pressure in weather reports, refrigeration and aviation in the United States, but is seldom used elsewhere....
  
  .
• IND: Indicator.
• INS: Inertial Navigation System
  Inertial navigation system
  An inertial navigation system is a navigation aid that uses a computer, motion sensors and rotation sensors to continuously calculate via dead reckoning the position, orientation, and velocity of a moving object without the need for external references...
  
  
• ISA: International Standard Atmosphere
  International Standard Atmosphere
  The International Standard Atmosphere is an atmospheric model of how the pressure, temperature, density, and viscosity of the Earth's atmosphere change over a wide range of altitudes. It has been established to provide a common reference for temperature and pressure and consists of tables of...
  
  .
• ISP: Integrated Switching Panel.
• ITT: Interstage Turbine Temperature.
• IVSI: Instantaneous Vertical Speed Indicator.

L

• LAAS
  Laas
  -Places:France:* Laas, Gers* Laas, Loiret* Laàs, in the Pyrénées-Atlantiques départementItaly:* Laas, South Tyrol, a municipality in South Tyrol-Acronym:* Laboratory for analysis and architecture of systems* Local Area Augmentation System...
  
  : Local Area Augmentation System
  Local Area Augmentation System
  The Local Area Augmentation System is an all-weather aircraft landing system based on real-time differential correction of the GPS signal. Local reference receivers located around the airport send data to a central location at the airport. This data is used to formulate a correction message, which...
  
  .
• LADGPS: Local Area Differential GPS.
• LCD: Liquid Crystal Display
  Liquid crystal display
  A liquid crystal display is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals . LCs do not emit light directly....
  
  .
• LDGPS: Local area Differential Global Positioning Satellite.
• LED
  LEd
  LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....
  
  : Light Emitting Diode.
• LMM: Locator Middle Marker.
• LOC: Localizer
  Localizer
  In aviation, a localizer is one of the components of an Instrument Landing System , and it provides runway centerline guidance to aircraft. In some cases, a course projected by localizer is at an angle to the runway . It is then called a Localizer Type Directional Aid...
  
  .
• LOM: Locator Outer Marker
  Locator Outer Marker
  A locator outer marker, or LOM, is a navigation aid used as part of an instrument landing system instrument approach for aircraft in the United States and other countries...
  
  .
• LRU: Line-replaceable unit
  Line-replaceable unit
  A line-replaceable unit is a modular component of an airplane, ship or spacecraft that is designed to be replaced quickly at an operating location. An LRU is usually a sealed unit such as a radio or other auxiliary equipment...
  
  

M

• MAP: Manifold Absolute Pressure or Missed Approach Point
  Missed approach point
  Missed approach point is the "point prescribed in each instrument approach at which a missed approach procedure shall be executed if the required visual reference does not exist." It defines the point for precision and non-precision approaches when the missed approach segment of a flight begins...
  
  .
• MB: Marker Beacon
  Marker beacon
  A marker beacon is a particular type of VHF radio beacon used in aviation, usually in conjunction with an instrument landing system , to give pilots a means to determine position along an established route to a destination such as a runway...
  
  .
• MCBF: Mean Cycles Between Failures.
• MDA: Minimum Decent Altitude.
• MEL: Minimum Equipment List
  Minimum equipment list
  In aviation, a Master Minimum Equipment List, or MMEL, is a categorized list of systems, instruments and equipment on an aircraft which are not required to be operative for flight. Specific procedures or conditions may be associated with operation with the relevant item inoperative...
  
  .
• MF: Medium Frequency
  Medium frequency
  Medium frequency refers to radio frequencies in the range of 300 kHz to 3 MHz. Part of this band is the medium wave AM broadcast band. The MF band is also known as the hectometer band or hectometer wave as the wavelengths range from ten down to one hectometers...
  
  .
• MFD: Multi-Function Display
  Multi-function display
  A Multi-function display is a small screen in an aircraft surrounded by multiple buttons that can be used to display information to the pilot in numerous configurable ways. Often an MFD will be used in concert with a Primary Flight Display. MFDs are part of the digital era of modern planes or...
  
  .
• MFDS
  MFDS
  MFDS is an exam offered by the Royal College of Surgeons. It stands for Membership of the Faculty of Dental Surgeons. The exam is a requirement to allow further specialist training for dentists in the UK and some Commonwealth countries...
  
  : Multi-Function Display System.
• MIC: Microphone
  Microphone
  A microphone is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal. In 1877, Emile Berliner invented the first microphone used as a telephone voice transmitter...
  
  .
• MILSPEC: Military Specification.
• MKR: Marker Beacon
  Marker beacon
  A marker beacon is a particular type of VHF radio beacon used in aviation, usually in conjunction with an instrument landing system , to give pilots a means to determine position along an established route to a destination such as a runway...
  
   or Marker
  Marker
  Marker may refer to:* Marker , a morpheme that indicates some grammatical function* Marker , a special-purpose computer* A set of sewing patterns tightly arranged within a rectangle that is placed over cloth to be cut...
  
  .
• MLS: Microwave Landing System
  Microwave landing system
  A microwave landing system is an all-weather, precision landing system originally intended to replace or supplement instrument landing systems...
  
  .
• MM: Middle Marker.
• MNPS: [Minimmum Navigation Performance Specifications]
• MMD: Moving Map Display.
• MOA: Military Operations Area
  Military Operations Area
  A military operations area is "airspace established outside Class A airspace to separate or segregate certain nonhazardous military activities from IFR Traffic and to identify for VFR traffic where these activities are conducted." Similar structures exist under international flight standards. ...
  
  .
• Mode A: Transponder
  Transponder
  In telecommunication, the term transponder has the following meanings:...
  
   pulse code reporting.
• Mode C: Transponder code and altitude reporting.
• Mode S: Transponder code, altitude, and TCAS reporting.
• MSG: Message
  Message
  A message in its most general meaning is an object of communication. It is a vessel which provides information. Yet, it can also be this information. Therefore, its meaning is dependent upon the context in which it is used; the term may apply to both the information and its form...
  
  .
• MSP: Modes S Specific Protocol.
• MSSS: Mode S Specific Services.
• MTBF: Mean Time Between Failures.
• MTTF: Mean Time To Failure
  Mean time to failure
  No artical exists on Wiki, please create one.In short Mean Time to Failure is the time taken for a part or system to fail for the first time.A very brief formula for the Mean Time To Failure of an event which occurs with probability P is: 1 / P....
  
  .

N

• NAS: National Airspace System
  National Airspace System
  The National Airspace System of the United States is one of the most complex aviation systems in the world — consisting of thousands of people, procedures, facilities, and pieces of equipment — that enables safe and expeditious air travel in the United States and over large portions of the world's...
  
  .
• NAV: Navigation receiver.
• Navaid: Navigational Aid
  Navigational aid
  A navigational aid is any sort of marker which aids the traveler in navigation; the term is most commonly used to refer to nautical or aviation travel...
  
  .
• NAVCOMM: Navigation and Communications equipment or receiver.
• NAVSTAR-GPS: The formal name for the space-borne or satellite navigation system.
• NCATT: National Center for Aircraft Technician Training.
• ND: Navigation Display.
• NDB: Non-Directional radio Beacon.
• NFF: No Fault Found.
• NM or NMI: Nautical Mile
  Nautical mile
  The nautical mile is a unit of length that is about one minute of arc of latitude along any meridian, but is approximately one minute of arc of longitude only at the equator...
  
  .
• NPA: Non-Precision Approach.

P

• PA: Public Adrress System.
• P-Code: GPS precision code.
• PAPI: Precision Approach Path Indicators.
• PAR: Precision Approach Radar
  Precision Approach Radar
  Precision approach radar is a type of radar guidance system designed to provide lateral and vertical guidance to an aircraft pilot for landing, until the landing threshold is reached. After the aircraft reaches the decision height or decision altitude , guidance is advisory only...
  
  .
• PD: Profile Descent.
• PDOP: Position Dilution Of Precision.
• PFD: Primary Flight Display
  Primary flight display
  A primary flight display or PFD is a modern aircraft instrument dedicated to flight information. Much like multi-function displays, primary flight displays are built around an LCD or CRT display device...
  
   or Primary Flight Director.
• PMG: Permanent Magnet Generator.
• PND: Primary Navigation Display.
• PNR: Passive Noise Reduction.
• POS: Position
  Position
  Position may refer to:* Position , a player role within a team* Position , the orientation of a baby prior to birth* Position , a mathematical identification of relative location...
  
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• P-RNAV: Precision Area Navigation.
• PSR: Primary Surveillance Radar.
• PTT: Push To Talk
  Push to talk
  Push-to-talk , also known as Press-to-Transmit, is a method of conversing on half-duplex communication lines, including two-way radio, using a momentary button to switch from voice reception mode to transmit mode....
  
  .

R

• RAI
  RAI
  RAI — Radiotelevisione italiana S.p.A. known until 1954 as Radio Audizioni Italiane, is the Italian state owned public service broadcaster controlled by the Ministry of Economic Development. Rai is the biggest television company in Italy...
  
  : Radio altimeter indicator.
• RAIM: Receiver autonomous integrity monitoring.
• RALT
  Ralt
  RALT was a manufacturer of single-seater racing cars, founded by ex-Jack Brabham associate Ron Tauranac after he sold out his interest in Brabham to Bernie Ecclestone. Ron and his brother had built some specials in Australia in the 1950s under the RALT name...
  
  : Radar
  Radar
  Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
  
   or radio altimeter.
• RAT: Ram Air Turbine
  Ram air turbine
  A ram air turbine is a small turbine that is connected to a hydraulic pump, or electrical generator, installed in an aircraft and used as a power source...
  
  
• RCR: Reverse current relay.
• RCVR
  RCVR
  - RCVR :RCVR is a transmedia science fiction series created for the internet by producer-director which offers an explanation for the exponential growth in science and technology since the late 19th century. The series was also produced by through production company Science To Fiction. The...
  
  : Receiver
  Receiver (radio)
  A radio receiver converts signals from a radio antenna to a usable form. It uses electronic filters to separate a wanted radio frequency signal from all other signals, the electronic amplifier increases the level suitable for further processing, and finally recovers the desired information through...
  
  .
• RDMI: Radio distance magnetic indicator.
• RDP: Radar data processing system.
• RDR: Radar
  Radar
  Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
  
  .
• REF: Reference
  Reference
  Reference is derived from Middle English referren, from Middle French rèférer, from Latin referre, "to carry back", formed from the prefix re- and ferre, "to bear"...
  
  .
• REL
  REL
  The proto-oncogene c-Rel is a protein that in humans is encoded by the REL gene. The c-Rel protein is a member of the NF-κB family of transcription factors and contains a Rel homology domain at its N-terminus and two C-terminal transactivation domains. c-Rel has an important role in B-cell...
  
  : Relative
  Relative
  -General use:*Kinship, the principle binding the most basic social units society. If two people are connected by circumstances of birth, they are said to be relatives-Philosophy:...
  
  .
• RF: Radio frequency
  Radio frequency
  Radio frequency is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals...
  
  .
• RFI: Radio frequency interference.
• RHSM: Reduced horizontal separation minimal.
• RLG: Ring laser gyroscope
  Ring laser gyroscope
  A ring laser gyroscope consists of a ring laser having two counter-propagating modes over the same path in order to detect rotation. It operates on the principle of the Sagnac effect which shifts the nulls of the internal standing wave pattern in response to angular rotation...
  
  .
• RLY: Relay
  Relay
  A relay is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism mechanically, but other operating principles are also used. Relays are used where it is necessary to control a circuit by a low-power signal , or where several circuits must be controlled...
  
  .
• RMI: Radio magnetic indicator.
• R-NAV: Area navigation
  Area navigation
  Area Navigation is a method of Instrument Flight Rules navigation that allows an aircraft to choose any course within a network of navigation beacons, rather than navigating directly to and from the beacons. This can conserve flight distance, reduce congestion, and allow flights into airports...
  
  .
• RNG
  Rng
  Rng can stand for* Random number generator* Rng , an algebraic structure similar to rings but without a multiplicative identity* .rng, the file extension of RELAX NG...
  
  : Range
  Range (aircraft)
  The maximal total range is the distance an aircraft can fly between takeoff and landing, as limited by fuel capacity in powered aircraft, or cross-country speed and environmental conditions in unpowered aircraft....
  
  .
• RNP: Required navigation performance
  Required Navigation Performance
  Required Navigation Performance is a type of performance-based navigation that allows an aircraft to fly a specific path between two 3-dimensionally defined points in space. RNAV and RNP systems are fundamentally similar. The key difference between them is the requirement for on-board...
  
  .
• ROC: Rate of climb
  Rate of climb
  In aeronautics, the rate of climb is an aircraft's vertical speed - the rate of change in altitude. In most ICAO member countries , this is usually expressed in feet per minute and can be abbreviated as ft/min. Elsewhere, it is commonly expressed in metres per second, abbreviated as m/s...
  
  .
• ROD: Rate of descent.
• RPM: Revolutions per minute
  Revolutions per minute
  Revolutions per minute is a measure of the frequency of a rotation. It annotates the number of full rotations completed in one minute around a fixed axis...
  
  .
• RTE
  Raidió Teilifís Éireann
  Raidió Teilifís Éireann is a semi-state company and the public service broadcaster of Ireland. It both produces programmes and broadcasts them on television, radio and the Internet. The radio service began on January 1, 1926, while regular television broadcasts began on December 31, 1961, making...
  
  : Route
  Road number
  A road number is often assigned to a stretch of public roadway. The number chosen is often dependent on the type of road, with numbers differentiating between interstates, motorways, arterial thoroughfares, two-lane roads, and so forth.-United Kingdom:...
  
  .
• RVR: Runway visual range
  Runway visual range
  Runway Visual Range is a term used in aviation meteorology to define the distance over which a pilot of an aircraft on the centreline of the runway can see the runway surface markings delineating the runway or identifying its centre line...
  
  .
• RVSM: Reduced vertical separation minimum.
• RX
  Rx
  RX is the telegraph and radio abbreviation for "receive" or "receiver".Rx, RX, or rx may also refer to:, medical prescriptions* Rx, the symbol used to describe apparent retrograde motion of planets...
  
  : Receiver
  Receiver (radio)
  A radio receiver converts signals from a radio antenna to a usable form. It uses electronic filters to separate a wanted radio frequency signal from all other signals, the electronic amplifier increases the level suitable for further processing, and finally recovers the desired information through...
  
  .

S

• SAT
  SAT
  The SAT Reasoning Test is a standardized test for college admissions in the United States. The SAT is owned, published, and developed by the College Board, a nonprofit organization in the United States. It was formerly developed, published, and scored by the Educational Testing Service which still...
  
  : Static Air Temperature.
• SATCOM: Satellite Communication.
• SATNAV: Satellite Navigation.
• SD: Secure Digital
  Secure Digital
  Secure Digital is a non-volatile memory card format developed by the SD Card Association for use in portable devices. The SD technology is used by more than 400 brands across dozens of product categories and more than 8,000 models, and is considered the de-facto industry standard.Secure Digital...
  
  .
• SELCAL: Selective Calling
  Selective calling
  In a conventional, analog two-way radio system, a standard radio has noise squelch or carrier squelch which allows a radio to receive all transmissions. Selective calling is used to address a subset of all two-way radios on a single radio frequency channel...
  
  
• SID: Standard Instrument Departure
  Standard Instrument Departure
  Standard instrument departure routes, also known as departure procedures are published flight procedures followed by aircraft on an IFR flight plan immediately after take-off from an airport.- Introduction :...
  
  .
• SIU: Satellite Interface Unit.
• S: Sensitivity Level.
• SMS
  SMS
  SMS is a form of text messaging communication on phones and mobile phones. The terms SMS or sms may also refer to:- Computer hardware :...
  
  : Short Messaging Service.
• SNR: Signal to Noise Ratio.
• SPKR: Speaker
  Loudspeaker
  A loudspeaker is an electroacoustic transducer that produces sound in response to an electrical audio signal input. Non-electrical loudspeakers were developed as accessories to telephone systems, but electronic amplification by vacuum tube made loudspeakers more generally useful...
  
  .
• SQ or SQL: Squelch
  Squelch
  In telecommunications, squelch is a circuit function that acts to suppress the audio output of a receiver in the absence of a sufficiently strong desired input signal.-Carrier squelch:...
  
  .
• SSCV/DR: Solid State Cockpit Voice/Data Recorder.
• SSCVR: Solid State Cockpit Voice Recorder.
• SSFDR: Solid State Flight Data Recorder.
• SSR: Secondary Surveillance Radar
  Secondary surveillance radar
  Secondary surveillance radar is a radar system used in air traffic control , that not only detects and measures the position of aircraft i.e. range and bearing, but also requests additional information from the aircraft itself such as its identity and altitude...
  
  .
• STAR: Standard Terminal Arrival Route
  Standard Terminal Arrival Route
  In aviation, a standard terminal arrival route or standard terminal arrival is a published procedure followed by aircraft on an IFR flight plan just before reaching a destination airport.-Description:...
  
  .
• STARS: Standard Terminal Automation Replacement System
  Standard Terminal Automation Replacement System
  The Standard Terminal Automation Replacement System is an air traffic control automation system currently being used in many TRACONs around the United States. STARS is intended to replace the Automated Radar Terminal System...
  
  .
• STC: Supplemental Type Certificate
  Supplemental Type Certificate
  A Supplemental Type Certificate is an FAA approved major modification or repair to an existing type certified aircraft, engine or propeller. As it adds to the existing type certificate, it is deemed 'supplemental'.-Purpose:...
  
  .
• STP: Standard Temperature and Pressure.
• SUA: Special Use Airspace
  Special use airspace
  Special use airspace , is an area designated for operations of a nature such that limitations may be imposed on aircraft not participating in those operations. Often these operations are of a military nature...
  
  .

T

• TA: Traffic Advisory (TCAS).
• TACAN: Tactical air navigation system.
• Tach: Tachometer
  Tachometer
  A tachometer is an instrument measuring the rotation speed of a shaft or disk, as in a motor or other machine. The device usually displays the revolutions per minute on a calibrated analogue dial, but digital displays are increasingly common...
  
  .
• TAD: Terrain Awareness Display.
• TAF: Terminal Area Forecast.
• TAS: True Airspeed
  True airspeed
  True airspeed of an aircraft is the speed of the aircraft relative to the airmass in which it is flying. True airspeed is important information for accurate navigation of an aircraft.-Performance:...
  
  .
• TAT
  TAT
  TAT is a rock/punk band hailing from London, England consisting of Tatiana DeMaria , Nick Kent and Jake Reed .-Early years :...
  
  : True Air Temperature or Total Air Temperature
  Total air temperature
  Total air temperature is a term used generally in aviation. In other applications it is called stagnation temperature. Total air temperature is measured by a specially designed temperature probe mounted on the surface of the aircraft. The probe is designed to bring the air to rest relative to the...
  
  .
• TAWS: Terrain Awareness Warning System.
• TBO: Time Before Overhaul or Time Between Overhaul
  Time between overhaul
  One important measure of an aircraft engine's overall economics is how often it has to be overhauled, the so-called time between overhaul, typically seen as TBO or TBOH....
  
  .
• TCA: Throttle Control Assembly or Terminal Control Area
  Terminal Control Area
  A terminal control area , also known as a terminal manoeuvring area in Europe, is an aviation term to describe a designated area of controlled airspace surrounding a major airport where there is a high volume of traffic...
  
  .
• TCAS: Traffic Collision Alert and avoidance System.
• TCF: Terrain Clearance Floor.
• TCN
  TCN
  TCN stands for:* Take Care Now, a private company providing out-of-hours medical cover in England* TanenbaumCHAT North Campus, a private Hebrew high school in Richmond Hill, Ontario, Canada* TCN-9, a Sydney television station...
  
  : TACAN
• TCU: TACAN Control Unit.
• TDOP: Time Dilution Of Precision.
• TDR: Transponder
  Transponder
  In telecommunication, the term transponder has the following meanings:...
  
   (in some cases).
• TERPS: Terminal Instrument Procedures or Terminal EnRoute Procedures.
• TFR: Temporary Flight Restrictions.
• TFT: Thin Film Transistor.
• TGT: Turbine Gas Temperature or Target.
• THDG: True Heading.
• TIAS
  Tias
  TIAS or Tias can refer to:*Tías, Las Palmas, a municipality in the Canary Islands*Treaties and Other International Acts Series published by the United States Department of State...
  
  : True Indicated Airspeed.
• TIS: Traffic Information Service.
• TK: Track Angle.
• TKE: Track Angle Error.
• TLA: Three Letter Acronym.
• TOGA: Take Off/Go Around thrust
• TOT: Turbine Outlet Temperature.
• TR or T/R: Transmitter Receiver or transceiver
  Transceiver
  A transceiver is a device comprising both a transmitter and a receiver which are combined and share common circuitry or a single housing. When no circuitry is common between transmit and receive functions, the device is a transmitter-receiver. The term originated in the early 1920s...
  
  .
• TRACON: Terminal Radar Approach Control.
• TRANS
  Trans
  Trans is a Latin noun or prefix, meaning "across", "beyond" or "on the opposite side".Trans may refer to:- Science and technology :* Cis-trans isomerism, in chemistry, a form of stereoisomerism...
  
  : Transmit, Transmission
  Transmission (telecommunications)
  Transmission, in telecommunications, is the process of sending, propagating and receiving an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired, optical fiber or wireless...
  
  , or Transition
  Transition
  Transition or transitional may refer to:* Transition economy* Transition function* Transition * Transitional government* Transition * Transition , a flying car made by Terrafugia...
  
  .
• TRK: Track
  Ground track
  A ground track or ground trace is the path on the surface of the Earth directly below an aircraft or satellite. In the case of a satellite, it is the projection of the satellite's orbit onto the surface of the Earth .A satellite ground track may be thought of as a path along the Earth's surface...
  
  .
• TRP: Mode S Transponder.
• TTR: TCAS II Transmitter/Receiver.
• TTS: Time to Station.
• TVE: Total Vertical Error.
• TWDL: Two-Way Data Link, or Terminal Weather Data Link.
• TWDR: Terminal Doppler Weather Radar
  Terminal Doppler Weather Radar
  Terminal Doppler Weather Radar is a doppler weather radar system used primarily for the detection of hazardous wind shear conditions on and near major airports in the United States. As of 2011, there were 48 active radars, across the United States & Puerto Rico. Several more radars have also been...
  
  .
• TWIP
  Twip
  A twip is a typographical measurement, defined as 1/20 of a typographical point...
  
  : Terminal Weather Information for Pilots.
• TWR: Terminal Weather Radar.
• TX: Transmit.

U

• UART: Universal Asynchronous Receiver Transmitter.
• UHF: Ultra-High Frequency.
• ULB: Underwater Locator Beacon
  Underwater locator beacon
  An underwater locator beacon or underwater acoustic beacon is a device fitted to aviation flight recorders such as the cockpit voice recorder and flight data recorder. ULBs are also sometimes required to be attached directly to an aircraft fuselage...
  
  .
• USB: Universal Serial Bus
  Universal Serial Bus
  USB is an industry standard developed in the mid-1990s that defines the cables, connectors and protocols used in a bus for connection, communication and power supply between computers and electronic devices....
  
  .
• UTC: Universal Time Coordinate.

V

• V
  Volt
  The volt is the SI derived unit for electric potential, electric potential difference, and electromotive force. The volt is named in honor of the Italian physicist Alessandro Volta , who invented the voltaic pile, possibly the first chemical battery.- Definition :A single volt is defined as the...
  
  : Volts or voltage
  Voltage
  Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...
  
  .
• VASI: Visual Approach Slope Indicator
  Visual Approach Slope Indicator
  The visual approach slope indicator is a system of lights on the side of an airport runway threshold that provides visual descent guidance information during the approach to a runway...
  
  .
• VDL: VHF Data Link
  VHF Data Link
  The VHF Data Link or VHF Digital Link is a means of sending information between aircraft and ground stations . Aeronautical VHF data links use the band 117.975 - 137 MHz assigned by the International Telecommunication Union to Aeronautical Mobile Route Services...
  
  .
• VDR: VHF Digital Radio.
• VFO: Variable Frequency Oscillator.
• VFR: Visual Flight Rules
  Visual flight rules
  Visual flight rules are a set of regulations which allow a pilot to operate an aircraft in weather conditions generally clear enough to allow the pilot to see where the aircraft is going. Specifically, the weather must be better than basic VFR weather minimums, as specified in the rules of the...
  
  .
• VG/DG: Vertical Gyroscope/Directional Gyroscope.
• VGA: Video Graphics Array
  Video Graphics Array
  Video Graphics Array refers specifically to the display hardware first introduced with the IBM PS/2 line of computers in 1987, but through its widespread adoption has also come to mean either an analog computer display standard, the 15-pin D-subminiature VGA connector or the 640×480 resolution...
  
  .
• VHF: Very High Frequency
  Very high frequency
  Very high frequency is the radio frequency range from 30 MHz to 300 MHz. Frequencies immediately below VHF are denoted High frequency , and the next higher frequencies are known as Ultra high frequency...
  
  .
• V/L: VOR/Localizer.
• VMC: Visual meteorological conditions
  Visual meteorological conditions
  In aviation, visual meteorological conditions is an aviation flight category in which visual flight rules flight is permitted—that is, conditions in which pilots have sufficient visibility to fly the aircraft maintaining visual separation from terrain and other aircraft. They are the opposite of...
  
   or minimum control speed with critical engine out.
• V/NAV: Vertical Navigation.
• VNE: never exceed speed.
• VNO: maximum structural cruising speed.
• VNR: VHF Navigation Receiver.
• VOR
  VHF omnidirectional range
  VOR, short for VHF omnidirectional radio range, is a type of radio navigation system for aircraft. A VOR ground station broadcasts a VHF radio composite signal including the station's identifier, voice , and navigation signal. The identifier is typically a two- or three-letter string in Morse code...
  
  : VHF Omnidirectional Range
  VHF omnidirectional range
  VOR, short for VHF omnidirectional radio range, is a type of radio navigation system for aircraft. A VOR ground station broadcasts a VHF radio composite signal including the station's identifier, voice , and navigation signal. The identifier is typically a two- or three-letter string in Morse code...
  
   and Ranging.
• VOR/DME: VOR
  VHF omnidirectional range
  VOR, short for VHF omnidirectional radio range, is a type of radio navigation system for aircraft. A VOR ground station broadcasts a VHF radio composite signal including the station's identifier, voice , and navigation signal. The identifier is typically a two- or three-letter string in Morse code...
  
   with Distance Measuring Equipment
  Distance Measuring Equipment
  Distance measuring equipment is a transponder-based radio navigation technology that measures distance by timing the propagation delay of VHF or UHF radio signals....
  
  .
• VOR/MB: VOR Marker Beacon.
• VORTAC: VOR and TACAN combination.
• VOX: Voice Transmission.
• VPATH: Vertical Path.
• V/R: Voltage Regulator
  Voltage regulator
  A voltage regulator is an electrical regulator designed to automatically maintain a constant voltage level. A voltage regulator may be a simple "feed-forward" design or may include negative feedback control loops. It may use an electromechanical mechanism, or electronic components...
  
  .
• V/REF: Reference Velocity.
• V/S: Vertical Speed.
• VSI: Vertical Speed Indicator.
• VSM: Vertical Separation Limit.
• VSO: stall speed in landing configuration.
• VSWR: Voltage Standing Wave Ratio.
• V/TRK: Vertical Track.
• VX: speed for best angle of climb.
• VY: speed for best rate of climb.

W

• WAAS: Wide Area Augmentation System
  Wide Area Augmentation System
  The Wide Area Augmentation System is an air navigation aid developed by the Federal Aviation Administration to augment the Global Positioning System , with the goal of improving its accuracy, integrity, and availability...
  
  .
• WD/WINDR: Wind Direction
  Wind direction
  Wind direction is reported by the direction from which it originates. For example, a northerly wind blows from the north to the south. Wind direction is usually reported in cardinal directions or in azimuth degrees...
  
  .
• WMA: WXR Waveguide Adapter.
• WMI: WXR Indicator Mount.
• WMS: Wide area Master Station.
• WMSC: Weather Message Switching Center.
• WMSCR: Weather Message Switching Center Replacement.
• WPT: Waypoint
  Waypoint
  A waypoint is a reference point in physical space used for purposes of navigation.-Concept:Waypoints are sets of coordinates that identify a point in physical space. Coordinates used can vary depending on the application. For terrestrial navigation these coordinates can include longitude and...
  
  .
• WRT: WXR Receiver Transmitter.
• WX
  Weather
  Weather is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. Most weather phenomena occur in the troposphere, just below the stratosphere. Weather refers, generally, to day-to-day temperature and precipitation activity, whereas climate...
  
  : Weather
  Weather
  Weather is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. Most weather phenomena occur in the troposphere, just below the stratosphere. Weather refers, generally, to day-to-day temperature and precipitation activity, whereas climate...
  
  .
• WXR
  Weather radar
  Weather radar, also called weather surveillance radar and Doppler weather radar, is a type of radar used to locate precipitation, calculate its motion, estimate its type . Modern weather radars are mostly pulse-Doppler radars, capable of detecting the motion of rain droplets in addition to the...
  
  : Weather radar system
  Weather radar
  Weather radar, also called weather surveillance radar and Doppler weather radar, is a type of radar used to locate precipitation, calculate its motion, estimate its type . Modern weather radars are mostly pulse-Doppler radars, capable of detecting the motion of rain droplets in addition to the...
  
  .
• WYPT: Waypoint
  Waypoint
  A waypoint is a reference point in physical space used for purposes of navigation.-Concept:Waypoints are sets of coordinates that identify a point in physical space. Coordinates used can vary depending on the application. For terrestrial navigation these coordinates can include longitude and...
  
  .

X

• XCVR: Transceiver
  Transceiver
  A transceiver is a device comprising both a transmitter and a receiver which are combined and share common circuitry or a single housing. When no circuitry is common between transmit and receive functions, the device is a transmitter-receiver. The term originated in the early 1920s...
  
  .
• XFR: Transfer.
• XMIT: Transmit.
• XMSN: Transmission
  Transmission (telecommunications)
  Transmission, in telecommunications, is the process of sending, propagating and receiving an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired, optical fiber or wireless...
  
  .
• XMTR: Transmitter
  Transmitter
  In electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating...
  
  .
• XPDR: Transponder
  Transponder
  In telecommunication, the term transponder has the following meanings:...
  
  .
• XTK: crosstrack
  Crosstrack
  Crosstrack, the "unique track switching game", is an abstract strategy game created by Shoptaugh Games in 1994. Players place special track pieces onto an irregular octagon board, winning by being the first to create an unbroken path between two opposite sides.-All games:Play begins with an empty...
  
  .