The avalanche season is now well underway in Switzerland. Until 9 January 2016, there had been only one victim for the season, which officially started on 1 October 2015. Now after the weekend there are five. The average death toll per season is around 25. Last season was worse than normal and claimed 35 lives in Switzerland.
The Valais police in Switzerland have called on people not to go off-piste if they lack the necessary knowledge and experience and are not with mountain guides or very experienced people.
While knowledge of the mountains and snowfall that experienced mountain guides possess is likely to reduce the risk of avalanche death it offers no guarantee. Even experienced guides and their clients get caught in avalanches. A sobering study by the Swiss Institute for Snow and Avalanche Research (SLF) (in French or in German) shows the percentage of avalanche victims who were guided. In the roughly five year period to 31 March 2006, 18% of victims were guided.
The study does however, suggest that guides got better at their job. In the 1980s 38% of those dying in avalanches were guided.
Guides in this study included mountain guides, ski instructors, backcountry guides, youth and sports instructors, members of the army and in two cases school teachers. Experienced amateurs were excluded from the definition. Over the most recent 15 year period in the study the percentage of total avalanche deaths among those travelling with a guide held steady at around 20%.
The chart above shows the number of avalanche deaths among those venturing off-piste with a guide (in solid red), and those without a guide (in solid yellow). The dotted lines are smoothed trend lines. The chart is from SLF and spans the period from 1 October 1981 to 30 September 2006. The worst season shown for guide-accompanied deaths was 1989 /90 when 17 died. The best was 1995/6 when no one who went off-piste with a guide in Switzerland perished.
It is however difficult to draw any conclusion from these numbers without knowing how many people in each category ventured off-piste. If we knew how many people were skiing off-piste guided and how many were going unguided then these figures could be combined with the respective number of guided and unguided victims to compute comparable survival rates. A simple split of avalanche victims into those who were guided and those who weren’t yields little information on the risk-reducing powers of a guide.
Taking a hypothetical example, if there were four times as many unguided skiers heading off-piste as those accompanied by a guide then the survival rate would be the same, assuming 20% of the victims were guided.
- Swiss avalanche deaths (Le News – 17.01.16)
- The colourful history of Swiss mountain air rescue (Le News – 07.10.15)
According to another survey, Sport Suisse 2014, an estimated 3.9% of Swiss residents (based on an interview sample of 10,652) go backcountry touring on skis, snowboards or snowshoes an average of 10 times a year. This adds up to an estimated 3.2 million outings a year. Unfortunately, the percentage of trips made with a guide versus those without was not included in the survey.
The only conclusion that can really be drawn from this data is that off-piste skiing carries risks even when accompanied by a guide. It might be possible to reduce the risk but it can’t be eliminated.
SLF avalanche bulletin (in English)