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SWITCH TO 406

By Carole Smith, NSS

All false emergency locator transmitter (ELT) alerts place a burden on Canada’s search and rescue (SAR) system, and most importantly, may divert resources from responding promptly to an actual aircraft in distress. Pilots, air traffic controllers, and flight service specialists who overhear ELT signals on 121.5 MHz also take time away from other duties to forward these alerts to rescue authorities.

A few simple rules of thumb can help aircraft owners, operators, and maintainers minimize false ELT alerts. SAR is a shared responsibility, and we can all do our part.

406 MHz ELTs

An ELT operating on a primary frequency of 406 MHz sends a half-second digital burst transmission once every 50 seconds. This coded signal is captured by the COSPAS-SARSAT satellites, and relayed automatically to SAR authorities. The unique code is then crossreferenced with the Canadian Beacon Registry to obtain vital information about the aircraft in distress.

It is important to note that all 406 MHz ELTs also transmit a continuous analog homing signal on 121.5 MHz. While the 121.5 MHz signal is no longer detected by satellite, it is used by SAR aircraft and ground crews to travel the final distance to the scene of an accident, particularly when visibility is reduced due to precipitation, terrain, vegetation, or darkness.

The following actions can help minimize false alerts from 406 MHz ELTs:

• Register your 406 MHz ELT with the Canadian Beacon Registry System. It’s required by the Canadian Aviation Regulations (CARs). Registration is free, and can be completed on-line at www.canadianbeaconregistry.forces.gc.ca; by calling 1-877-406-SOS1 (7671); or by faxing a completed registration form to 1-877-406-FAX8 (3298). It is recommended that registration be completed even before installation. If a 406 MHz ELT is activated by mistake while being installed, an alert can be more quickly resolved if a point of contact has been registered.
• Carry out routine operational checks of 406 MHz ELTs in strict accordance with the manufacturer’s instructions, as each model has its own unique test procedure. Consider building this protocol into your operating checklists, as applicable. The manufacturer’s documentation will also indicate how often these checks should be carried out to ensure that the maximum battery life of the unit is preserved.
• Routine 406 MHz ELT tests that involve transmission of the 121.5 MHz homing signal should only be carried out during the first five min of every UTC hour, and for a duration of five seconds or less.
• The digital signal from a 406 MHz ELT that is turned on for approximately 50 seconds or more will be captured by the SAR satellites, and interpreted as a distress transmission. If you believe that this may have happened in error, contact the Canadian Mission Control Centre at 1-800-211-8107. The staff will welcome your call, and there is no fine or charge levied by the SAR system for inadvertent activations of this kind.
• Keep your Canadian Beacon Registry information up to date. If you or your emergency contacts move, or if you buy, sell, or substantially reconfigure your aircraft (e.g. new paint colours, change floats to wheels, etc.), be sure to update your record. If the aircraft is sold, and the 406 MHz ELT registration is not updated, the original owner will be called if the ELT is triggered. This confusion could delay a rescue effort. It is also a good idea to update your record when the ELT is removed from the aircraft for re-certification or for extended storage.

121.5 MHz ELTs

As of February 1, 2009, signals from ELTs operating on a primary frequency of 121.5 MHz (and/or 243 MHz) are no longer captured by SAR satellites. However, 121.5 MHz is still monitored by air traffic control towers and flight service stations during their hours of operation, and by some aircraft. ELT signals overheard on 121.5 MHz are reported to SAR authorities as possible distress transmissions.

The following actions can help minimize false alerts from 121.5 MHz ELTs:

• Test your 121.5 MHz ELT only during the first five min of every UTC hour, and for a duration of five seconds or less.
• Contact your closest joint rescue coordination centre if your 121.5 MHz ELT activates by mistake. Include the location, time, and duration of the inadvertent transmission, if known. There is no fine or charge levied by the SAR system, and the rescue controller will welcome the opportunity to focus on another case that might involve an actual aircraft in distress.

An important note on ELT disposal

An increasing number of 121.5 MHz ELTs are being removed from service as aircraft are fitted with newer 406 MHz units. It is very important to ensure that these 121.5 MHz units are properly decommissioned, including removing the battery from the unit and disabling the electronics. Several unnecessary searches have concluded at local garbage dumps due to an emergency beacon that had been improperly discarded. Curious children have also activated ELTs and other types of emergency beacons after finding them around the house or workshop.

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