RECCO
The Recco system is an electronic method of finding a person or persons buried in snow as a result of an avalanche.
History
The Recco system was developed in response to an avalanche tragedy that involved the inventor, Magnus Granhed, in Åre, Sweden, in 1973.
Magnus collaborated with researchers at the Royal Institute of Technology in Stockholm, at first studying all the existing technologies. Although active avalanche transceiver were found to be most effective, but transceivers had disadvantages of high cost, the need to turn them on and off, and a requirement for batteries. This led Magnus to look at a passive reflector that could be carried by a skier all times and would be a simple and practical solution.
In 1975 John Lawton, the developer of the Skadi avalanche transceiver, proposed that a reflector could be put on a lift ticket. During the northern-hemisphere winter of 1978/1979 Magnus worked in conjunction with the Royal Institute of Technology in Stockholm, painstakingly conducting an experiment to measuring radio frequency penetration of snow. All winter, radio waves were sent into the snow, and by varying the frequencies every few hours an optimum frequency for penetration of the snowpack was arrived at.