Nathan VanderKlippe
Northern News Services

Trenton, Ont. (Oct 29/01) - Sitting at the Rescue Coordination Centre (RCC) at Canadian Forces Base Trenton, air controller Pierre Bolduc watches satellites glide over maps of Canada.

About 100 times a day, a blip flashes on the screen where the satellite has picked up an emergency signal. Most of the time, those blips are errant signals picked up by the six search and rescue satellites in polar rotation around the earth.

The hyper-sensitive eyes in the sky, set in orbit in the early 1980s by Canada, Russia, France and the U.S., can be triggered by a malfunctioning microwave.

But occasionally the blip is the first indication of an emergency.

When an aircraft crashes, like the one in Fort Liard two weeks ago, its emergency locator transmitter is jolted into action, broadcasting a distress signal on 121.5 MHz. An overhead satellite picks up that signal and uses the doppler effect (which measures signal frequency changes due to motion) to determine its approximate position.

The satellite downloads that information to a ground receiving station, known as a local user terminal (LUT), which forwards it to the satellite mission control centre at Trenton, located on the north shore of Lake Ontario about 100 kilometres east of Toronto. About 20 minutes later, a computer finishes crunching the raw data and spits out two sets of coordinates for the crash: one real, one called a "phantom" signal.

Then the wait begins for coordinates from a second satellite pass, which can take anywhere from two minutes to two hours. High-flying aircraft in the vicinity are contacted to verify the ELT signal. When the two sets of coordinates are matched in Western Canada, the RCC places a call to CFB Winnipeg and a Hercules C-130 search and rescue plane is dispatched. Depending on the signal strength the RCC can provide a coordinate that is accurate to anywhere from 10 to 35 kilometres.

Winging along at 700 km/h, the Hercules is outfitted with direction-finding equipment that hones in more precisely on the signal. When the location is found, search and rescue teams are usually parachuted in. Aircraft from local air companies are chartered to fly to the site and rescue victims. So far this year, the Trenton RCC has responded to almost 300 distress beacons.