Emergency Locator Transmitter
The ELT is a battery-powered transmitter that will detect automatically any unusual deceleration force such as that associated with a crash and subsequently transmit a distress signal on a designated frequency.
There are currently in service two types of ELTs, the older ELTs that transmit on frequency 121.5 MHz, and the newer ELTs that transmit on 406 MHz. 121.5 ELTs used to be monitored by a dedicated satellite system, but this was phased out in 2009 and replaced by 406 ELTS, which continue to be monitored by the COSPAS-SARSAT satellite systems.
If properly maintained, the ELT is designed to have sufficient power to transmit the signal (which is a wailing sound similar to a siren) for 48 hours at -20°C. An 406 ELT signal is detected by the satellites within minutes. As well, high altitude commercial and military aircraft normally monitor 121.5 MHz and can typically detect the 121.5 ELT signals within 100 miles of crash site. All aircraft should monitor 121.5 MHz when able, especially in sparsely settled areas.
An ELT signal announces your distress and enables the satellite systems to determine your approximate position. Search and Rescue systems are then alerted and use the ELT signal to home in on your location rapidly.
On every flight, ensure the ELT is armed (if practical), and ensure every passenger is aware of the ELT location and operation. ELT information should be displayed in the aircraft. After landing, if your aircraft is equipped with a 121.5 ELT, check 121.5 MHz to ensure that your ELT has not been inadvertently activated.
In the event of an emergency you should of course, while airborne, transmit “Mayday,” squawk 7700 on the transponder, and broadcast your position. After the crash or forced landing, place the ELT function switch to “ON” immediately. Once the ELT is turned on, do not switch it off until you have been rescued. Satellites and rescue aircraft need a continuous transmission to locate the aircraft and home to its position.
An ELT signal can be improved by, if possible, removing the ELT from the aircraft and setting it vertically on the highest nearby point, ensuring that it remains connected to its antenna.1 Always stay with the aircraft and set up a survival camp, and prepare signal fires or some other means of attracting the attention of search aircraft.2
In the event that no emergency exists—e.g., you have conducted a precautionary landing to wait out bad weather—make attempts to contact overflying aircraft or Air Traffic Services. If not successful, switch on the ELT one-hour after the expiry of your flight plan or itinerary, as this is when the search for an overdue aircraft will begin. The ELT transmission in such cases will lesson the costs of the search and upon arrival of the search aircraft you can contact them via radio and advise of your intentions.
An ELT is only as good as the batteries. The replacement of batteries must be in accordance with the manufacturer’s instructions. ELTs maay only be tested in the first five minutes of every hour.
To avoid false alarms, always switch “OFF” the ELT whenever it is removed from the aircraft. Disconnect the batteries if the ELT is being shipped. In the event of an inadvertent broadcast, advise Air Traffic Services that there is no emergency.
1 Raising the ELT 8 feet will increase its range by 20 to 40%. Additionally, by placing the transmitter on a piece of metal such as the aircraft wing will provide reflectivity and will extend transmission range.
2 If you land in an uninhabited area, the best course of action is to stay with the aircraft and the ELT. The idea here is that the aircraft is far easier to see than people are. Make all efforts to make yourself visible from the air—i.e., have smoke, flares, signal fires, etc., ready to attack attention.