Emergency Locator Transmitter (ELT)
An emergency locator transmitter (ELT) is a self-powered radio beacon carried aboard an aircraft that activates automatically under the G-forces of a crash — or manually from a cockpit switch — and broadcasts a distress signal so search and rescue can find the aircraft. Under Canadian regulations, ELTs must now transmit simultaneously on 406 MHz, the digital frequency monitored by satellite, and 121.5 MHz, used by rescue crews for final homing.
How it works
When the ELT activates, it sends a coded digital burst on 406 MHz to the international COSPAS-SARSAT satellite system. The satellites fix the beacon’s position and relay it, along with the aircraft’s registered identity, to the Joint Rescue Coordination Centre. Once searchers are in the area, they home in on the ELT’s continuous 121.5 MHz signal — which is also why you monitor 121.5 in flight and report any ELT signal you hear to ATC.
Why the 406 part matters: satellites stopped monitoring 121.5 MHz in 2009. An old 121.5-only ELT can crash with you into the bush and nobody is listening unless an overflying aircraft happens to hear it. A 406 MHz beacon is detected by satellite within minutes — but only helps searchers identify you if it is registered, free of charge, with the Canadian Beacon Registry.
The Canadian rules
CAR 605.38 requires an ELT on board for most Canadian aircraft, with a short list of exemptions: gliders, balloons, airships, ultralight aeroplanes and gyroplanes. Transport Canada phased in the 406 MHz requirement over several years — commercial and private operators by November 2021, recreational operators by November 2025 — so a 121.5-only unit no longer meets the general requirement.
Testing is tightly controlled, because a live test is indistinguishable from a real distress signal. An ELT may only be tested during the first five minutes of any UTC hour, and only briefly, in accordance with the manufacturer’s instructions. If you activate one accidentally — a hard landing will sometimes do it — switch it off and tell the nearest ATS unit immediately so a search isn’t launched.
On the exam
ELT questions on the PSTAR, PPAER and in the ROC-A tend to test four things: the two frequencies and which does what (406 alerts the satellite, 121.5 is for homing), the testing window (first five minutes of the UTC hour), the exempt aircraft types, and what to do when you hear an ELT signal or trigger one accidentally. Know those four and you have the topic covered.