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 (typically 121.5 MHz, 243.0 MHz, and 406 MHz) to help search and rescue services locate a downed aircraft.
Plain English
A small emergency radio fitted to the aircraft. If the aircraft crashes, it switches itself on and sends out a signal so rescuers can find where the aircraft came down.
Context Anchor
Pilots encounter ELTs during preflight checks, aircraft equipment inspections, emergency procedures, and search-and-rescue discussions.
Derivation
From 'emergency' (a sudden serious situation requiring action), 'locator' (something that helps find a position), and 'transmitter' (a device that sends out a radio signal). The name describes exactly what it does — sends a signal to help locate you in an emergency.
Why Pilots Care
Federal regulations require ELTs on most powered aircraft because a working unit can mean the difference between a timely rescue and remaining lost after an off-airport landing.
Intuition Check
An ELT is not a radio for talking to rescuers. It mainly sends out a distress signal so the aircraft can be found.
Example Sentence 1
During preflight, the pilot checked that the ELT switch was in the ARM position so it would activate automatically if needed.
Example Sentence 2
During the preflight inspection the pilot verified that the aircraft ELT battery was within its replacement date.