04.11.2025
The typical skier avalanche is around 50-70 meters wide and has about three times the flow length. The fracture depth (also known as the break-off height ) is around half a meter on average. Most people die in avalanches as a result of suffocation (approx. 57%) or fatal injuries (30%). As a general rule, the chances of survival decrease with increasing burial time.
You don’t have to die in an avalanche, and many avalanche accidents fortunately have a mild outcome, i.e. almost no consequences. However, freeriders often suffer serious or even life-threatening injuries. As soon as you are caught in an avalanche, you are a passenger and it is difficult to influence the outcome of this event.
It is therefore important to avoid an avalanche as far as possible and to always consider the consequences of an avalanche in the current situation (burial depth, risk of collision and falling, burial time, number of buried people and helpers, emergency call and flying weather, etc.).
Several components always come together in an avalanche accident:
The graphs illustrate very clearly how important it is to rescue companions quickly. Almost two thirds (i.e. 2 out of 3) of all avalanche fatalities died from suffocation. Hypothermia, on the other hand, is of secondary importance, but can very well become an issue after excavation while waiting for the rescue services (heat management!).
The survival curve, also known statistically as the survival function, shows the probability of still being alive in an avalanche over the course of a complete burial. It describes a gradual decrease in the probability of survival and allows the chances of survival during a complete burial to be divided into four phases:
During the first 10 minutes* after a burial, the probability of survival remains very high at around 90 percent. During this phase, around 10 percent of accident victims die, mainly from fatal injuries. According to statistics, around 50 percent of buried victims are freed from the snow masses in these first 10 minutes.
*According to a EURAC study, the time span in which the probability of survival of avalanche victims is higher than 90 percent has been reduced from 15 minutes to 10 minutes!
This is followed by a steep drop in the curve. Approximately two thirds of all completely buried victims die from lack of oxygen in the following 20 minutes.
After 30 minutes, only completely buried people with a sufficient oxygen supply survive. They are able to breathe in the snow, their airways are clear and there is a sufficiently large cavity in front of their mouth to prevent the air from becoming supersaturated with CO₂. Only a few buried victims die during the latency phase. The survival function therefore shows a very flat curve from 30 to approx. 90 minutes.
However, after 90 minutes of burial (which roughly corresponds to the standard time for organized rescue), the chance of survival decreases again. In this phase, three factors lead to death: severe hypothermia, lack of oxygen and an increase in carbon dioxide (due to the rebreathing of exhaled air).
In those cases in which buried persons have a larger breathing cavity, i.e. a cavity in front of their mouth and nose or a connection to the outside air, it is even possible for them to survive a burial for several hours.
In the 1990s, a study was conducted in which the survival phase was 15 minutes (Falk et al. 1994). This study by Falk et al. has now been revisited in 2024. The study by Eurac Research, Swiss emergency physicians and the Swiss Institute for Snow and Avalanche Research SLF in Davos provides interesting results. The research team examined avalanche data from the past 40 years (from 1643 avalanche victims) from Switzerland who were critically buried between 1981 and 2020 – meaning that at least their head and upper body were under the snow. People who were only partially buried or not buried at all were not included.
The results were compared with data from the 1994 study. Both studies used the same statistical approach (Turnbull algorithm) to calculate the chances of survival.
Rauch S, Brugger H, Falk M, et al. Avalanche Survival Rates in Switzerland, 1981-2020. JAMA Netw Open. 2024;7(9):e2435253. doi:10.1001/jamanetworkopen.2024.35253.
Falk M, Brugger H, Adler-Kastner L. Avalanche survival chances. Nature. 1994;368(6466):21. doi:10.1038/368021a0.
Haegeli P, Falk M, Brugger H, Etter HJ, Boyd J. Comparison of avalanche survival patterns in Canada and Switzerland. CMAJ. 2011;183(7):789-795. doi:10.1503/cmaj.101435.
Procter E, Strapazzon G, Dal Cappello T, Zweifel B, Würtele A, Renner A, Falk M, Brugger H. Burial duration, depth and air pocket explain avalanche survival patterns in Austria and Switzerland. Resuscitation. 2016;105:173-176.
Brugger H, Durrer B, Adler-Kastner L, Falk M, Tschirky F. Field management of avalanche victims. Resuscitation. 2001;51(1):7-15.