Aviation Safety Letter 2/2004

Locating Aircraft In Case of Emergency

New 406 MHz Emergency Locator Transmitters (ELTs)

Reprinted from R&D Update, Transportation Development Centre (TDC), November 2003 (TP 10913).

To alert search and rescue authorities of the location of a downed plane, most Canadian aircraft are required to carry ELTs that automatically send a radio signal that can be detected by a satellite.

The first generation of these beacons operated at 121.5 MHz and has been responsible for saving thousands of lives around the world since the very first rescue in British Columbia in 1982. However, these beacons also suffered from a serious problem of false alarms. A new generation of more reliable ELTs that operate at 406 MHz offers far superior search and rescue response. The beacons are more readily detected by satellites, transmit codes that identify each beacon and its owner, and allow the origin of the signal to be detected to within a radius of between two and five kilometres.

Changing the satellite network

COSPAS-SARSAT, the international satellite search and rescue network, has announced that as of 2009, it will no longer recognize signals from 121.5 MHz ELTs.

At the same time, regulators such as Transport Canada have been reluctant to order the general aviation community to switch to 406 MHz ELTs because the significantly higher cost may deter small aircraft owners from buying one. While 121.5 MHz beacons sell for under $1 500, 406 MHz beacons currently on the market can cost as much as $3 500.

Off-the-shelf components

With support from the National Search and Rescue Secretariat's New Initiatives Fund, research coordinated by TDC found that a much less expensive 406 MHz ELT beacon was feasible using off-the-shelf components and a simplified design. Design work included the development of miniaturized electronics, power sources, and reliable activation devices, as well as component and packaging design that complies with civil aviation regulations and that can withstand a harsh operating environment. The new ELT features a lithium battery, specially designed signal amplifiers, and an automatic gain control circuit. A working prototype has been constructed and work is underway on the production engineering, which is expected to bring the cost down within the same range as 121.5 MHz beacons.

The prototype was certified by COSPAS-SARSAT earlier this year and has been submitted to Transport Canada for regulatory approval. This research program will put lifesaving technology within the reach of most aircraft owners.

For more information on this project, contact Howard Posluns at 514-283-0034 or poslunh@tc.gc.ca.

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