General (ICAO)

The Emergency Locator Transmitter (ELT) is an emergency beacon triggered on impact, water contact, or manually, transmitting a distress signal that can be located by the COSPAS-SARSAT satellite system and SAR direction-finding equipment. Coverage in ICAO Annex 6 Part II, Annex 10 Vol III and Annex 12.

Frequencies (ICAO Annex 10 Vol III):

406 MHz — primary distress frequency, digitally encoded, received by COSPAS-SARSAT satellites worldwide. Transmits a 24-bit ID (hex code) uniquely identifying the aircraft, and optionally GPS position (if the ELT is GPS-equipped). Accuracy: 2–5 km without GPS, <100 m with GPS.
121.5 MHz — analogue swept tone, direction-finding capable by on-board kit and SAR helicopters; no longer satellite-monitored since 1 Feb 2009 (COSPAS-SARSAT terminated 121.5 MHz monitoring). 121.5 MHz now serves only for homing by SAR aircraft.
243 MHz (military UHF distress) — additionally transmitted by many ELTs.

ELT types:

Automatic Fixed (AF) — permanently installed, triggered by G-switch (impact).
Automatic Portable (AP) — permanently installed, removable.
Automatic Deployable (AD) — automatically ejected on impact (e.g. life-jacket ELT).
Survival ELT (ELT(S)) — portable, manually activated, in emergency kit.

Test/maintenance: Permitted only within the first 5 minutes of each hour and only brief tests (max. 3 audio sweeps) — to prevent false alarms.

Registration: 406 MHz ELTs must be registered with the national authority so the ELT ID is linked to the aircraft, owner and emergency contacts.

Europe (EASA / EU)

Carriage obligation EU-wide via Regulation (EU) 965/2012 (Air Operations):

Part-NCO.IDE.A.170 for non-commercial aeroplane operations.
Part-CAT.IDE.A.280 for commercial air transport.
At least one ELT of an appropriate type must be carried; over water additional requirements apply.

Frequencies: 406 MHz is the standard; many units also transmit on 121.5 MHz for homing.

Germany (national)

Registration authority: Bundesnetzagentur (BNetzA) administers the 15-digit hexadecimal ELT identifier. The owner must update registration upon sale/transfer.

False alarm: Anyone who triggers an ELT inadvertently must immediately notify the nearest FIS or RCC Münster (+49 251 135 757) to avoid unnecessary SAR launches. Otherwise the response costs can be charged to the owner.