Emergency Locator Transmitter

The ELT answers exactly one question after a forced landing: will rescuers find me, and how fast? A registered 406 MHz beacon answers it far better than the legacy 121.5, and the difference can be the difference between hours and days.

406 MHz versus 121.5 MHz

There are two generations of ELT, and the distinction is worth knowing cold:

• 121.5 MHz is the old analog beacon. The crucial fact: satellites no longer monitor 121.5. The international Cospas-Sarsat system stopped satellite processing of 121.5 MHz on February 1, 2009 — so a 121.5-only ELT is detected only by aircraft and ground stations that happen to be listening, with no automatic satellite alert and only a coarse fix. It survives as a homing frequency that search aircraft use to walk in on a signal once they're already looking.
• 406 MHz is the digital beacon, and it's a different category of capability. It is detected by satellites, it transmits a registered digital identity (so responders instantly know whose airplane it is and how to reach your contacts), and a GPS-equipped 406 ELT encodes your latitude and longitude — turning a wide search into a pinpoint.

The takeaway: a 406 ELT converts "somewhere out there" into "right here," and does it automatically. That's why it's the modern standard.

Register it, and know how to fire it

A 406 ELT is only as good as its registration (with NOAA). An unregistered 406 beacon still alerts the satellites, but it strips responders of the owner, aircraft, and contact data that lets them confirm a real emergency and launch quickly — it becomes an anonymous blip instead of a name and a phone number. Registration is free and it's the single highest-leverage thing an owner does for their own rescue.

Know how yours activates. ELTs fire automatically on a crash g-switch (a sharp deceleration), and they can be triggered manually from a cockpit remote switch or on the unit itself. After any hard landing, two habits: check it didn't false-trigger — monitor 121.5 and listen for your own beacon, because an inadvertent activation ties up search resources — and conversely, if you're ever down and the automatic switch didn't fire, turn it on manually. Don't assume it activated.

Keeping it legal

<CFR id="91.207" /> makes the ELT a maintained, current item, not a box that lives in the tail forever:

• Battery must be replaced (or recharged, if rechargeable) after one cumulative hour of transmitter use, or when 50% of its useful life has expired — with the new date marked on the unit and logged.
• The ELT gets a 12-month inspection covering proper installation, battery corrosion, the controls and crash sensor, and a sufficient signal from the antenna.

And mind testing etiquette (AIM): if you ever test a 121.5 ELT, do it only during the first five minutes of the hour, for no more than three audible sweeps, so you don't trip a false alarm during the windows responders watch most closely.