SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/cap-406-beacons

Which emergency beacon frequency can search and rescue satellites detect today?

406 MHz, the only frequency satellites can pick up.

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  1. 121.5 MHz
  2. 243 MHz
  3. 406 MHz ✔

Why: 406 MHz beacons send a digital signal to satellites. Older 121.5 MHz beacons are no longer detected by satellites.

Huh, didn't know that: NOAA says 406 MHz beacons built for aircraft are called Emergency Locator Transmitters, or ELTs.

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References

Answer: 406 MHz. 406 MHz beacons send a digital signal to satellites. Older 121.5 MHz beacons are no longer detected by satellites.

  1. NOAA SARSAT: 406 MHz Emergency Distress Beacons www.sarsat.noaa.gov/emergency-406-beacons
    406 MHz is the only frequency satellites can pick up in the event of a distress activation.
    Checked 2026-10-10.
  2. NOAA SARSAT: 406 MHz Emergency Distress Beacons www.sarsat.noaa.gov/emergency-406-beacons
    406 MHz beacons designed for use in an aircraft are known as an Emergency Locator Transmitter (ELT).
    Checked 2026-10-10.

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Test yourself in the game

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