Aviation Dictionary

On this page you will find a searchable and comprehensive alphabetical list of aviation terms. You can help us make it the most comprehensive list in the world. If we have missed anything, click on the ‘send us your word’ button to send us your word, acronym or definition and we will consider adding it to our dictionary.

Aviation Dictionary: E

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EAS	Equivalent air speed
ECT	Evening Civil Twilight. This begins when the sun is 6 degrees below the horizon and ends at sunrise
EET	Estimated elapsed time
EFATO	Engine failure after take-off
EFIS	Electronic flight instrument system
EGT	Exhaust gas temperature
EICAS	Engine indication and crew alerting system
Electronic Flight Bag (EFB)	An Electronic Flight Bag (EFB) is an electronic device that hosts applications which allow flight crews to perform functions that were traditionally done using paper products and tools. Two Australian examples are AvPlan and Oz Runways. A US example is Jeppesen Aviator.
Elevation	The height of any point on the ground above mean sea level (AMSL). As an example, an aerodrom could be 50 feet AMSL, which means it is 50 feet above the level of the sea.
Elevator	The horizontal control surface located on the tail plane and controls the pitch of the aircraft around the lateral axis.
ELR	Environmental lapse rate
ELT	Emergency Locator Transmitter. A device, which can either be portable or fixed in the aircraft that transmits a signal in the event of an emergency. Depending on the ELT, it may have to be manually turned on, or in most cases will be automatically turned on after some high impact. There is the possibility that a hard landing could activate an ELT. There are specific time periods to test an ELT on 121.5 MHz
Emergency	An inflight emergency would mean that the aircraft and/or occupants are in severe danger and a mayday call would be submitted
Engine Failure	Is when the engine stops producing power, either due to a loss of fuel or other fluids, or due to mechanical failure. Partial engine failures also occur, and some power may still be available.
EOBT	Estimated off-block time. The estimated time that the aircraft moves off the gate to proceed for a departure
EPR	Engine pressure ratio
EPT	Effective performance time
Equator	An imaginary circle that divides the Northern and Southern hemisphere. It is directly in the middle between the North and South pole
Equilibrium	This refers to the forces acting upon the aircraft in flight, which would all be in balance. In other words, lift = weight and thrust = drag
ERC	En route chart
ERSA	En route supplement Australia
ETA	Estimated time of arrival
ETD	Estimated time of departure
ETI	Estimated time interval
ETOPS	Extended range twin operations
ETP	Equi-time point
Exosphere	The outermost layer of the earth’s atmosphere

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Aviation Dictionary