Definition
A self-contained, battery-powered radio transmitter installed in an aircraft that automatically activates on impact and broadcasts a distress signal on designated emergency frequencies (121.5 MHz, 243.0 MHz, and/or 406 MHz) to help search and rescue services locate the aircraft after a crash or forced landing.
Plain English
A small radio beacon fitted to the aircraft that switches itself on if the airplane crashes, sending out a signal so rescuers can find it.
Context Anchor
Pilots encounter this term when checking required emergency equipment, reviewing aircraft records, or learning what happens after an accident or forced landing.
Derivation
Each word carries its operational meaning directly: 'emergency' (the situation it serves), 'locator' (helps find the aircraft), 'transmitter' (sends a radio signal). The name describes exactly what the device does.
Why Pilots Care
It enables search and rescue teams to locate a downed aircraft quickly, which can be critical for survival after an off-airport landing.
Intuition Check
Do not think of it as a normal two-way aircraft radio. An emergency locator transmitter mainly sends out a distress signal; it is not used for ordinary conversation with air traffic control.
Example Sentence 1
During the preflight inspection, the pilot confirmed the emergency locator transmitter was armed and the battery was within its replacement date.
Example Sentence 2
During the preflight inspection the pilot verified the emergency locator transmitter battery expiration date was still valid.