Education and equipment reduce Swiss avalanche deaths

There has been a significant drop in the number of avalanche deaths in Switzerland over the last 30 years despite a marked rise in the number of winter sports enthusiasts going outside of marked and secured ski runs. That is according to an article by theSwiss Federal Institute for the Study of Snow and Avalanches and published in the December edition of the Swiss Alpine Club’s house magazine.

Using their database of mountain and winter sports accidents the Davos based institute has analyzed the 30 year period from 1977 to 2006. Over that time 3434 winter sports enthusiasts were buried in 1619 avalanche incidents resulting in 703 deaths. The number of burials runs at around 35 to 40 per year, this figure hasn’t changed. However the number of deaths has dropped from 27 during the first part of the period to 20 over the last 15 years. There has been an increase in the number of skier triggered avalanches, this can be partially explained by better reporting of minor incidents.

The media talks a great deal about the dangers taken by off-piste skiers. Currently 60% of incidents involve ski tourers and 40% off piste skiers. There is a very slight trend towards off-piste, however ski touring incidents are more serious (more victims per incident).

There has been a significant decrease in serious accidents involving guided groups (UIAGM, ski instructors and qualified club ski leaders). Guided groups also appear less frequently in statistics dropping from 40% of incidents in 1977 to 20% today. It should be remembered that such accidents often have legal ramifications for the group leader. Better education and appreciation of avalanche risks by leaders accounts for part of this improvement.

The number of live rescues has increased. At the end of the 1970s 60% of buried victims died compared to 40% today. Where a victim is rescued by companions the mortality has dropped from 34% to 20% compared to 88% to 70% for organized external rescue. The biggest factor is burial time which has decreased from 150 minutes in 1977 to 80 minutes at the start of the 1990s to 30 minutes today. For beacon wearers, the overall mortality rate has dropped from 49% to 29%. The widespread adoption of avalanche beacons and the improvement in technology as well as better training accounts for much of this improvement. The average burial depth for fatalities has remained constant at 120cm and 70cm for survivors.

The debate over multiple burials looks set to continue. The study showed that the number of multiple burial incidents has decreased to just 16% of accidents since 2000. Only 5% of incidents had more than two victims. However no distinction is made in these figures for “true” multiple burials, where special techniques must be used to isolate signals from beacons. This drop can be partially explained by the size of groups involved in avalanche incidents which has decreased from 3.6 to 2.8 but also by better education about group management and route choices. The report suggests that back-country enthusiasts focus their search and rescue training on efficient single victim searching, shovelling techniques and first aid.

The study also looked at the number of incidents at individual risk levels on the 5 point scale. Although there has been a significant increase in incidents at Considerable risk (3/5) when this is normalized against the number of days at this risk level there is no discernible trend. Moderate and Considerable risks concern the majority of Swiss incidents however it would appear that back-country enthusiasts are not taking more risks than previously.

Further Information

The article was first published at the ISSW in 2008

Posted by davidof on Tuesday, 13 January, 2009 at 05:12 PM

> My experience of Swiss skiers is that they are
> more risk averse/conservative than the French

So what’s the 20 - 30 year historical trend of burials and deaths in some region of France?

Another paradigm is that there’s several kinds of backcountry skiers: some are seeking risk, some want to try to ski powder every day, but for some it’s enough to ski some powder just once every couple of weeks.

So a possible interpretation of the Swiss results is that 30 years almost everybody who went out (with the limited knowledge they had back then) and skied backcountry or off-piste any significant number of days was a “risk-seeker” (or had lots of money to hire knowledgable guides).

As people discovered that better knowledge and procedures and more accurate forecasts sorta worked, more skiers in other risk-aversion categories started skiing more days. But a higher percentage of these newer skiers are not as subject to the “McCammon” principle.

Two other observations that contradict the McCammon principle:
(1) lots more people get buried on Level=3 days than Level=2 days. (but according to the McCammon principle the skiers should take advantage of the Level=2 by skiing more dangerous lines—and of course some do—but not all).
(2) lots more people get buried when there’s fresh snow at Level=4 or Level=3 _after_ several weeks of snow drought, than at Level=4 or 3 in the midst of frequent snow showers. (but if all skiers are seeking a constant degree of risk, this should not happen).

Claim: If more accurate and wide-available knowledge enables the “risk-averse powder seekers” to get what they want every week or two, lots fewer of them will get caught on avalanches.


Posted by  on  Tuesday, 20 January, 2009  at 07:21 PM

In my own opinion, the number of partial burials _reported_ does show an increasing trend but the authors interpret that as a changing trend in how incidents are reported and/or recorded.

Posted by  on  Tuesday, 26 June, 2012  at 01:28 PM
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