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 transceivers were most effective, their disadvantages such as high cost, the need to turn them on and off, and their need for batteries, made him decide that some sort of passive reflector carried by the skier would be a simple and practical solution.

In 1975, John Lawton had proposed that a reflector could be put on a lift ticket, John also developed the Skadi avalanche transceiver. During the winter of 1978/9 Magnus, in conjunction with the Royal Institute of Technology, Stockholm, painstakingly conducted an experiment. 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.

Magnus formed RECCO AB in 1980 and soon created a first prototype, which was heavy and cumbersome, but it worked.

25 years (2006) later the RECCO system now consists of a small portable detector which can easily be carried by one searcher, on foot or in a helicopter. These receivers are now standard equipment with search and rescue teams in most major ski resorts worldwide.

How it works
The reflector consists of a small, flat capsule, only about 1/2" by 2" by 1/16" thick, which contains a pair of foil aerials, joined by a diode. The size of the aerials makes the unit a tuned circuit resonating at one specific frequency.

The detector sends out a highly directional signal on that frequency from an aerial projecting from the front of the unit,  and if the signal ‘hits’ a reflector it is bounced back. And, due to the diode the returned signal is doubled in frequency, (Harmonic radar). Thus the detector tells the operator that it is pointing at a reflector, and not just a piece of metal the right 'length'.

The returned signal is translated into an audio tone whose volume is proportional to the returned signal, and by means of a volume control a trained rescue operator can literally go straight to the buried reflector once a signal is detected.

Notes on usage
Due to the water in a human body blocking the signal transmission, two reflectors placed on opposite sides of the body are recommended. Many high end garment manufacturers now place one in one jacket sleeve and one in the opposing side trouser leg. Some ski boots manufacturers, such as Atomic, place one in each boot. The reflectors are also available as self adhesive stickers to stick on your own boots.

Drawbacks
While extremely valuable for ski-resort-based rescue teams and ski patrols, the RECCO does not replace the older avalanche beacon technology Since the RECCO reflector is a passive locating device, users must realize that they have no ability within their party to locate each other (ie: reflectors cannot locate). Since the detector is heavy (1.6 kg ) approximately 4-5 times larger than most avalanche beacons, and expensive, it is not practical for ski touring parties, mountaineers or backcountry skiers to own or carry. In the event of an avalanche, the receiver would have to be brought to the accident location, which can take some time. Since 50% of avalanche victims deaths due to suffocation happen within the first 20 minutes, this makes it impractical for anything but ski resort use.