- ELT (emergency locator transmitter). A self-contained radio transmitter that automatically begins transmitting on the emergency frequencies any time it is triggered by a severe impact parallel to the longitudinal axis of the aircraft.
- Required by all U.S. civil airplane category aircraft except as provided below [91.207(e) and (f)].
- Transmits on 121.5 MHz or the newer 406 MHz (highly recommended).
- Batteries must be replaced after one hour of cumulative use or when 50 percent of their usable life has expired.
- Expiration date for replacing (or recharging) the battery must be legibly marked on the outside of the transmitter and entered in the aircraft maintenance record.
- Must be inspected every 12 calendar months.
- Testing of an analog 121.5 ELT can only be done within the first five minutes after the hour, and you may transmit no more than three audible sweeps.
- Digital 406 ELTs should only be tested in accordance with the manufacturer’s instructions.
- Airborne tests are not authorized for any ELT.
Operating without an ELT, a person may: [91.207(e)]
