Emergency locator transmitters are emergency transmitters required in almost all U.S. registered civil aircraft under 14 CFR Part 91.207. The ICAO Annex 6 Part IIA recommends an automatic unit for extended over-water flights. To install and maintain an ELT, the operator must guarantee it is properly attached so the probability of damage in the event of crash impact is minimized. The ELT must be inspected every 12 calendar months for proper installation, sufficient signal from its antenna and a functioning crash sensor; the rule further demands a separate sign-off at each annual inspection.
Inspection must decide battery condition: batteries used in the emergency locator transmitters must be replaced when 50% of their useful health has expired or after one cumulative hour of activation, and the ELT must be marked with an externally visible expiration date. The device may be activated by impact or manually and is therefore a key element of search-and-rescue readiness for any compliant aircraft.
Expert behind this article
Jim Goodrich
Jim Goodrich is a pilot, aviation expert and founder of Tsunami Air.
Do all aircraft need an ELT?
According to the 14 CFR 91.207 rule, all aircraft except gliders, balloons, airships, gyroplanes, powered parachutes, trikes, and homebuilts other than airplane are required to have an ELT. Even for airplanes that normally must carry one, 14 CFR 91.207(e) allows operation without an ELT under certain conditions, so a flight legally departs if the unit is temporarily removed for repair, inspection, or while a replacement is being obtained. Outside these spelled-out exceptions, however, an operable ELT is required, and the device must be registered.
What are the aircraft ELT requirements?
The aircraft ELT requirements are detailed below.
- Canada requires an ELT that can transmit a signal on 121.5 MHz and highly recommends an ELT that can transmit over 121.5 MHz and 406 MHz for aircraft ELT requirements.
- The FAA, ICAO, and Cospas-Sarsat require 406 MHz ELTs for international distress signaling as part of aircraft ELT requirements.
- The International Civil Aviation Organization (ICAO) standard is the 406 MHz ELT, which is included in aircraft ELT requirements.
- As per the ELT requirements, each emergency locator transmitter must be attached to the airplane in such a manner that the probability of damage to the transmitter in the event of crash impact is minimized.
- ELTs operate on 121.5 MHz, 243 MHz, or 406 MHz as part of aircraft ELT requirements.
- As per ELT requirements, aircraft records must contain an entry which includes the date of initial removal, the make, model, serial number, and reason for removing the transmitter, and a placard located in view of the pilot to show that the ELT is not installed.
- New installations of ELT equipment must meet the requirements in TSO-C126.
- The FAA requires ELT be registered with NOAA as part of aircraft ELT requirements.
- On and after January 1, 2004, aircraft with a maximum payload capacity of more than 18,000 pounds when used in air transportation are subject to the ELT requirements.
- The ELT must be secured with metal fasteners as recommended by the FAA for aircraft ELT requirements.
- No person may operate the aircraft more than 90 days after the ELT is initially removed from the aircraft under aircraft ELT requirements.
- Batteries used in the emergency locator transmitters must be replaced when 50% of their useful health has expired as per aircraft ELT requirements.
- The new 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 as per aircraft ELT requirements.
- After June 21, 1995, an ELT that meets the requirements of TSO-C91 may not be used for new installations according to aircraft ELT requirements.
- Each emergency locator transmitter must be inspected within 12 calendar months after the last inspection for proper installation as stated in aircraft ELT requirements.
How to test an aircraft ELT?
Every few months, or when originally installed and whenever parts are moved or replaced, pilots test their ELT in accordance with the manufacturer's instructions. A two-station test positions the aircraft about one-half kilometre from a tower, FSS or listening aircraft on 121.5 MHz. A single-station test tunes the aircraft receiver to 121.5 MHz. For a quick 121.5 MHz check, place an AM radio tuned to between-stations static within six inches of the antenna. If the antenna is removable, substitute a dummy load. With the 406Test, the beacon's self-test function satisfies annual inspections without satellite alert.
Which components should be checked during ELT inspection on an aircraft?
All components of an ELT are checked during an inspection. Each ELT must be inspected within 12 calendar-months after the last inspection. The unit must be removed from the mount so that mounting hardware is inspected for proper installation and security. While removed, the ELT is examined for physical condition, secure mounting, and no visible damage, and the battery compartment is checked for damage or corrosion. The battery itself is inspected for leakage, corrosion, or internal damage and its expiration date verified. Wiring and connections must be secure and corrosion-free. All interconnections to the ELT unit and antenna are disconnected so that connector pins can be visually inspected for proper seating. The control switch operation is tested for proper arming and activation, and an audio check confirms the signal tone without prolonged transmission. Antenna inspection covers proper attachment and condition, and signal strength is measured to guarantee the radiated signal is sufficiently strong to be received by a satellite in an emergency. After any maintenance involving ELT removal or reinstallation, or after inadvertent activation or use exceeding one cumulative hour, the same inspection sequence must be repeated.
