ELT
Emergency Locator Transmitter
Last updated: April 20, 2026 · Maintained by Aviatr Editorial Team
What is ELT?
An ELT (Emergency Locator Transmitter) is a distress-signalling device required on aircraft operating in EASA airspace. After an impact or manual activation, the ELT transmits on 406 MHz via the COSPAS-SARSAT satellite network, providing precise location data to search-and-rescue services worldwide within minutes.
How is ELT used?
406 MHz digital ELTs have been mandatory in European airspace since 2003-2005 (by aircraft category), replacing the older 121.5 MHz analog units whose satellite monitoring ended in 2009. Modern ELTs include an integrated GPS receiver that reports position within 100 metres, and each unit is registered in the COSPAS-SARSAT database with aircraft and owner details. Activation occurs automatically via a G-switch on impact or manually via a cockpit switch. The satellite system typically detects the signal within 5-10 minutes and relays it to the appropriate Rescue Coordination Centre, which then dispatches search-and-rescue assets. ELTs are tested on the ground during scheduled maintenance — inadvertent activations from hard landings or maintenance jolts are common and require immediate notification to the relevant authority to stand down any response. Pilots also monitor 121.5 MHz (still transmitted as a homing signal alongside 406 MHz) during cross-country flights to detect nearby ELT activations.