The Recco rescue system is an electronic method of finding people buried in an avalanche or lost in the outdoors.
Video RECCO
History
The Recco system was developed in response to an avalanche tragedy that involved the inventor, Magnus Granhed, in Åre, Sweden, in 1973. He was riding the ski lift to the Mörvikshummeln when he heard a tremendous roar. An avalanche had ripped down the very steep slopes of Svartberget. The result was chaos. Nobody knew how many people, or who, had been swept away in its path. "We started to search with our ski poles," recalls Magnus. Later, probes and avalanche rescue dogs arrived, but in those days that was the only help available. Magnus remembers feeling "utterly helpless poking a ski pole into the snow" in an area the size of two soccer fields. By the time they found the two buried skiers the search had gone on for hours and both skiers had died.
The accident in Åre set him thinking about the possibility of an electronic locating device to locate buried people. Granhed had just graduated with a Master of Science degree, and turned to Professor Bengt Enander, Department of Electromagnetic Theory at the Royal Institute of Technology in Stockholm.
After some testing they saw that thermal imaging did not work and transceivers were too limited. It led Magnus to come up with the concept of a passive reflector that could be carried by a skier at all times and would be a simple and practical solution. During the winter of 1978-1979 Magnus worked together with the Royal Institute of Technology in Stockholm, testing 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. It took Enander's team another two years to develop a harmonic radar that could be used to detect passive reflectors.
Magnus formed Recco AB in 1980 and soon created a first prototype; while it was heavy and cumbersome but it worked.
As of 2009 the active part of Recco system utilizes a small hand-held detector, which can easily be carried by one rescuer traveling on foot or from a helicopter. These detectors are now standard equipment with more than 800 ski resorts, mountain rescue teams, and parks worldwide.
Maps RECCO
How it works
The Recco system consists of two parts: a reflector (integrated into clothing, boots, helmets, and body protection) and a detector (used by professional rescue teams).
The detector sends out a highly directional signal and if the signal 'hits' a reflector it bounces back. The returned signal is translated into an audio tone if the detector is pointed in the direction of a reflector. Judging from the audio tone a trained professional can determine the location of a buried victim. 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 reflector is a small (13 mm × 51 mm × 1.5 mm), light (4g) and flat capsule that 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 reflector is passive meaning it has no batteries and it never has to be switched on. Recco recommends users be equipped with two reflectors placed on opposite sides of the body. Many garment manufacturers now place one in one jacket sleeve and one in the opposing side trouser leg.
Recco's newest, 9th generation, detector (R9) was released in 2009. The detector is the size of a school book and weighs 900 grams allowing for easy handling, and transportation. The signal sent from Recco detector passes through air, snow and ice. It's maximal range is up to 200 meters through air and up to 30 meters through snow. Signal's range through snow is dependent on snow's dryness. Liquid water absorbs the signal, therefore in spring time when the snow contains more liquid the snow range decreases. Rescuers need to make slight adjustments to their search tactics when searching in wet snow conditions. It is equipped with an avalanche transceiver which allows a single rescuer to perform both the search for Recco reflectors and 457 kHz avalanche beacons at the same time.
Usage
The search with the Recco detector is very similar to that of an avalanche beacon. The avalanche debris area is searched in 20m wide corridors. The detector can be used by a rescuer on foot, skis, or from a helicopter who aims the detector toward the snow. Once a signal is heard the operator orients the detector in the direction of the strongest signal and follows the tone along a straight line. When the tone disappears the rescuer is right above the victim. The detector is then aimed downwards at the snow and several rapid crisscross sweeps are done to pinpoint the signal. Unlike an avalanche beacon the Recco detector is truly directional and accurately pinpoints the location. A probe pole is recommended to determine the burial depth.
The time to search with the Recco detector is about the same as the search time with a transceiver so large areas can be searched very quickly.
Other applications
The Recco technology has gained popularity among researchers of some amphibian species, especially tropical frogs. The system allows researchers to track small frogs in their natural habitat. It "is enabling scientists to begin unravelling the complex world of small-amphibian behavior in the hope that better understanding will improve conservation."
Capabilities
The Recco system is not intended for companion rescue and is not a substitute to transceiver use in the backcountry. The Recco detector is another tool for organized rescue teams that complements their other search methods including rescue dogs, transceiver, and probe lines.
The system was originally developed for use at ski resorts where it is already recognized to be extremely valuable for ski-resort-based rescue teams and ski patrols. However, its value is not confined only to ski resorts. Even in the backcountry, Recco has demonstrated its capability to find buried victims quickly.
Time is the enemy of all buried avalanche victims, and devices and technologies that can significantly reduce search times can make a difference for buried victims. Transceivers, Recco, and dogs are all much faster than probe lines.
In 2015, Recco introduced the SAR-1 helicopter detector that expands the use of technology from avalanches to finding missing people in mountains, forest, and water.
The June 2016 issue of the Journal of Wilderness and Environmental Medicine presents the case report of a live rescue of a buried off-piste skier using Recco equipment that occurred in Spain 2015.
References
External links
- Recco AB homepage
Source of article : Wikipedia
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