Item: Statistical analyses on multiple burial situations and search strategies for multiple burials
Title: Statistical analyses on multiple burial situations and search strategies for multiple burials
Proceedings: 2002 International Snow Science Workshop, Penticton, British Columbia
Authors: Manuel Genswein, Stephan Harvey, Swiss Federal Institute for Snow and Avalanche Research (SLF), Davos
Abstract: Recent statistical analysis based on 466 skier triggered avalanches in Switzerland from almost 30 years (winter 1970/71 to 1998/99) causing 698 completely buried people show that a surprisingly high percentage of victims get caught and completely buried in avalanches producing multiple burial situations. The analysis where focused on victims which could not be found by visible parts, so all of them clearly match the criteria for transceiver search. This surprisingly high percentage is an important sign for the importance of the multiple burial criteria in transceiver training, in testing, as well as in the further development of transceivers and specialized training solutions. The transceiver search for multiple burials always presents lay and professional rescuers with a difficult task. Manufacturers suggest various, transceiver technology specific search approaches, which makes training demanding and time consuming. The proposed search approach requires, on the one hand, a thorough analysis of the burial situation, and on the other, a systematic search procedure that can be applied in any situation and independently of the transceiver technology. This systematic way makes the system teachable and therefore learnable. The experience in the field of transceiver based pinpointing systems for deep burials has already shown that many experienced and professional rescuers have developed their own, for themselves highly efficient search strategies. However, it is often very difficult to formalize such highly individualistic approaches in order to make them available to a wider public. The thorough and continuous analysis of the burial situation tells the rescuer at any time how many victims there are in which radius around him. This information allows to define an appropriate search strategy. The systematic search procedure is based on the idea that a clear signal isolation makes locating an avalanche victim easier for human ears with an analogue transceiver - but as well for a digital transceiver. Taking differences in signal strength as criteria to separate the different transmitters from each other, all zones where one individual signal is significantly stronger relative to the other signals have to be discovered. This situation can be found where the rescuer is close to a certain victim relative to the others. Applying the micro search strip search strategy the searcher systematically scans the potential area for those zones close to transmitters where one signal is significantly stronger than the other ones. The more victims there are and the closer they are together, the narrower is the micro search strip width: The strip width is reverse proportional to the spatial density of the burials.
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Keywords: avalanche accident, avalanche incident, avalanche accident statistics, avalanche rescue, transceiver search, multiple burials
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