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ATC, ILS, MLS? Aviation Acronyms Explained

Posted on October 18, 2017

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If you spend enough time hanging around Pilots or airplanes you’re bound to hear lots of acronyms such as ILS, OAT, MSA and a whole bunch more.

Whether you’re a student pilots, considering flights training, or just an all around aviation geek, here are some of the more common aviation acronyms, explained.

 

Who’s Who

ATC – Air Traffic Control

A service provided by a state’s aviation authority to promote the safe, orderly and expeditious flow of air traffic.

AO - Aircraft Operator
Organizations and people who own or operate the equipment, procedures and information used to support the aircraft’s overall missions

CFI - Certified Flight Instructor
A pilot who's certified by a states aviation authority to offer aircraft instruction

PIC - Pilot in Command
The pilot responsible for the control and operation of the aircraft during flight

SIC - Second in Command
The pilot who is designated to take over control of an aircraft under direction of the pilot in command

FBO - Fixed-Base Operator
Supplier of fuel, maintenance, flight training and other services at an airport

FSS - Flight Service Station
Facilities that provide pilot briefings and routine en-route communications

EFAS - En Route Flight Advisory Service
Technology that provides en route aircraft with flight updates and important weather alerts

GA - General Aviation
The portion of civil aviation that refers to flights other than military, scheduled airline and cargo flights

Operational Abbreviations

VFR - Visual Flight Rules
Guidelines governing flights flown solely by reference to visual cues

IFR - Instrument Flight Rules
Guidelines governing flights under conditions in which it’s not safe to fly using only visual references

VMC - Visual Meteorological Conditions
Weather conditions that allow for VFR

IMC - Instrument Meteorological Conditions
Weather conditions that require IFR

AVGAS - Aviation Gasoline
Piston aircraft fuel

MEL - Minimum Equipment List
A list of instruments, equipment and procedures necessary to pilot a specific aircraft

UNICOM - Universal Communication
A common radio frequency used at uncontrolled (non-tower) airports for local pilot communication

METAR - Meteorological Aerodrome Report
Weather conditions observed at an airport

ATD - Actual Time of Departure
The time a pilot takes off from an airstrip or airport

ETD - Estimated Time of Departure
The time a pilot plans to take off from an airstrip or airport

ATA - Actual Time of Arrival
The time a pilot lands at a destination

ETA - Estimated Time of Arrival
The time a pilot plans to land at a destination

ATIS - Automated Terminal Information Service
Continuous broadcast of vital information including wind direction, velocity, pressure readings and active runway assignments

AFM - Airplane Flight Manuals
Documents developed by the aircraft manufacturer and approved by a state’s aviation authority, containing information and instructions required to operate the aircraft

POH - Pilot's Operating Handbook
Document developed by the aircraft manufacturer containing the approved AFM

Instrumentation

A/C - Aircraft
Refers to an aircraft, not air-conditioning

ADI - Attitude Direction Indicator
An instrument that shows the aircraft's orientation relative to the horizon, shows the roll and pitch of the aircraft

DME - Distance Measuring Equipment
An instrument that measures slant range distance from a nav aid

ALT - Altimeter
An instrument that measures an aircraft's altitude

HDG - Heading
The direction the aircraft's nose is pointing

NAV - Navigation System
The aircraft's directional system

GPS - Global Positioning System
Satellite-based navigation information

VSI - Vertical Speed Indicator
An instrument that displays an aircraft's rate of climb or descent

OAT - Outside Air Temperature Gauge
An instrument that displays the temperature of the air immediately outside the aircraft

EHSI (or HSI) - Electronic Horizontal Situation Indicator
Combines a heading indicator instrument with course deviation indicator

VOR - VHF Omnidirectional Range
Short-range, ground-based radio navigation system for aircraft

A Few Common In-Flight Terms

CAS - Calibrated Airspeed
The indicated airspeed of an aircraft, corrected for position and instrument error

IAS - Indicated Airspeed
A direct instrument reading not corrected for position and instrument error

CAT - Clear Air Turbulence
Turbulent conditions absent of visual indicators such as clouds

CAVU - Ceiling and Visibility Unlimited
Ideal flying weather

AGL - Above Ground Level
Measurement of altitude above a specific land mass

MSL - Mean Sea Level
The average height off the surface of the sea for all stages of tide

ALS - Approach Light System
Lighting system on the approach end of the airport runway

AGR - Air-Ground Ranging
Straight-line distance from the aircraft to a point on the ground

 

Disclaimer: All material provided or discussed in these blogs or articles are purely for informational and entertainment purposes. None of this information or material should be thought of, or construed as, or a replacement, or supplement for flight and ground instruction. You must always seek formal information from an approved flight training organisation before undertaking any sort of flight or ground instruction.

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