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Glossary of Aviation Acronyms

Acronym Description
A&P Airframe and Power plant — Generally refers to an aircraft mechanic who is certified to work on both the power plant (engine) and the airframe for aircraft. (Ref.: FAR §65.85, §65.87)
AC Advisory Circular — The FAA issues advisory circulars to inform the aviation public of non-regulatory material. Unless incorporated into a regulation by reference, the contents of an advisory circular are not binding on the public.
AD Airworthiness Directive — The FAA issues airworthiness directives in response to deficiencies or unsafe conditions found in aircraft, engines, propellers, or other aircraft parts. For type-certified aircraft, ADs must be followed to remain in compliance with the FAA. (Ref.: FAR §39.7)
ADAHRS Air Data, Attitude and Heading Reference System — Similar to AHRS (see below) but providing additional information, such as airspeed and OAT.
ADS-B Automatic Dependent Surveillance - Broadcast — A surveillance technology in which an aircraft determines its position via satellite navigation and periodically broadcasts it, enabling it to be tracked. (Ref.: Wikipedia)
ADS-R Automatic Dependent Surveillance - Rebroadcast — A client-based service that relays ADS-B information transmitted by an aircraft broadcasting on one link (1090MHz or 978MHz) to aircraft equipped with ADS-B In on the other link. (Ref.: FAA: ADS-B Ins and Outs)
AHRS Attitude and Heading Reference System — A system of electronic sensors on three axes that provide attitude (roll, pitch, yaw) and heading (directional) information. Often integrated with an EFIS in either panel mounted (permanent) or portable configurations.
AIM Aeronautical Information Manual — Official guide to basic flight information. (Ref. FAA PDF)
AMT Aviation Maintenance Technician
AOPA Aircraft Owners and Pilots Association
BFR Biennial Flight Review – All certificated pilots must complete a Flight Review (formerly known as a biennial flight review) every 24 months. (Ref.: FAR §61.56)
CFI or CFII Certified Flight Instructor [Instrument]
CFR Code of Federal Regulations (also e-CFR for “electronic” CFR)
CHT Cylinder Head Temperature
DA Density Altitude — Pressure altitude corrected for nonstandard temperature. As temperature and altitude increase, air density decreases. In a sense, DA is the altitude at which the airplane "feels" its flying. (Ref.: AOPA)
DAR Designated Airworthiness Representative — An individual designated by the FAA to act on its behalf in the certification of type-certificated and amateur-built aircraft for the issuance of airworthiness certificates, special flight permits, import aircraft, export certificates for products and articles, conformity inspections and field approvals for repair and alterations. (Ref. Wikipedia)
DPE Designated Pilot Examiner — A person designated by the FAA to conduct the practical test (checkride).
EAA Experimental Aircraft Association
EA-B or EAB Experimental Amateur-Built — See FAQ.
EFB Electronic Flight Bag — Instrument (such as a tablet or smartphone) that manages pilot information electronically. This could include charts, location, flight plans, weather reports, aircraft documents, and other information. Examples include ForeFlight and Garmin Pilot running on an Apple iPad.
EFIS Electronic Flight Information System — Electronic instrument that displays attitude, airspeed, altitude, turn rate, time, or other information. Typically part of a "glass" panel or cockpit.
EGT Exhaust Gas Temperature
ELSA or E-SLA Experimental Light Sport Aircraft — A kit version of a S-LSA. (Ref.: Sport Aviation Specialties)
EMS Engine Monitoring System — Electronic instrument that monitors and displays engine information such as: fuel level and burn rate, RPM, manifold pressure, cylinder hear temps, oil temp and pressure, amperage, voltage, exhaust gas temps, and other information.
FAR Federal Aviation Regulations (e-CFT link to FAR)
FIS-B Flight Information Service - Broadcast — A component of ADS-B technology that provides free graphical National Weather Service products, temporary flight restrictions (TFRs), and special use airspace information. (Ref.: SkyRadar.net, FAA)
FSDO Flight Standards District Office — FSDO is a locally affiliated field office of the FAA. Delta and Montrose counties in Colorado are serviced by the Utah FSDO in Salt Lake City. (Ref. FAA website)
GPS Global Positioning System — Often GPS refers to a device capable of receiving information from a global navigation satellite system.
GUMPS Gas, Undercarriage, Mixture, Prop, Seatbelts and/or Switches — Widely used pre-landing mental checklist to remind the pilot to check: fuel (tank, pressure, pump), landing gear (down), mixture (rich), propeller (high RPM), seatbelts (fastened) and switches (lights, pitot heat, etc.).
IA Inspection Authority — Generally refers to an A&P mechanic who is certified to perform inspections. Sometimes called an A&I, meaning "A&P with IA" (Ref.: FAR §65.91)
ICAO International Civil Aviation Organization — A UN specialized agency established to manage the administration and governance of international air navigation.
MEI Multi-Engine Instructor
LODA Letter Of Deviation Authority — A formal authorization issued by the FAA Flight Standards office authorizing a deviation from specified section(s) of FAR.
LOP Lean Of Peak — Leaning the fuel/air mixture to peak EGT, then continuing the leaning process to a certain temperature lean of peak.
LSA Light-Sport Aircraft — Any aircraft that meets the LSA definition can be flown by Sport Pilots with the appropriate endorsements. See FAQ. (Ref.: FAR §1.1, search the page for "light-sport")
LSRM Light-Sport Repairman - Maintenance
OAT Outside Air Temperature
OL Operating Limitations
PA Pressure Altitude — Used in aircraft performance calculations. To find pressure altitude, set your altimeter to 29.92 (standard pressure).
POH Pilot’s Operating Handbook — This is essentially the “owner’s manual” for the airplane.
PPL Private Pilot License — There is no such distinction in the FAR. Informally, this term is synonymous with “private pilot certificate”. (Ref.: FAR §61.113, Wikipedia)
ROP Rich Of Peak — Leaning the fuel/air mixture to peak EGT, then enriching the mixture to a certain temperature rich of peak.
SLSA or S-LSA Special Light Sport Aircraft — Factory-built aircraft constructed to an industry consensus standard and sold with a special airworthiness certification. See FAQ. (Ref.: Sport Aviation Specialties)
STOL Short TakeOff and Landing
TCAS Traffic Collision Avoidance System — An aircraft collision avoidance system designed to reduce the incidence of mid-air collisions between aircraft. (Ref.: Wikipedia)
TIS-B Traffic Information Service - Broadcast — A component of ADS-B technology that provides free traffic reporting services to aircraft equipped with ADS-B receivers. TIS-B allows non-ADS-B transponder equipped aircraft that are tracked by radar to have their location and track information broadcast to ADS-B equipped aircraft. (Ref.: SkyRadar.net, FAA, AOPA article)
TSO Technical Standard Order — A minimum performance standard established by the FAA for specified materials, parts, and appliances used on civil aircraft.
WAAS Wide Area Augmentation System — An air navigation aid developed by the FAA to augment GPS. WAAS is intended to enable aircraft to rely on GPS for all phases of flight, including precision approaches. (Ref.: Wikipedia)


For more definitions, see Part 1 of the Federal Aviation Regulations, including §1.1 General definitions and §1.2 Abbreviations and symbols.

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