For those whose Norwegian is a little bit rusty:
http://www.ngi.no/upload/Sn%C3%B8skred/Ulykker/Fatal%20accident_2012_19March_Sorbmegaisa.pdf
The report provides some detailed assessments of the snowpack, which was poised for a deep slab avalanche.
Unfortunately, no information on the decision making, but given that the decisions were being made by a commercial guiding operation, that kind of information in such a context will most likely become known only via the possibility of some sort of government investigation or lawsuit, e.g., Bay Street.
After reading the report, a few other questions arise. No signal from the survivor's beacon was detected. Not turned on, or damaged during/prior to the incident?
ReplyDeleteAlso, the report states that the guide deployed his airbag pack but, "This was the second fatal accident in Norway this winter where a person with deployed airbag (avalanche pack) is deeply buried." Is there a correlation between a deployed airbag and the depth of burial? Could the airbag allow one to be carried into a terrain trap where the volume of snow is much greater and can overwhelm the advantage of the airbag or is a Class 5 avy just generally unsurvivable? Have you seen a report from the other incident?
Re lack of beacon signal, given the factors of a professionally guided group plus a big avalanche plus the surprisingly minimal beacon impact spec (1m drop onto hard wooden surface) = most likely explanation would appear to be damaged in the avy (which has happened previously in at least one documented U.S. incident)
ReplyDeleteRe mechanically successful yet ultimately ineffective airbag deployment, I have not seen the report for the other such Norwegian incident, but in the course of researching my article for The Avalanche Review on airbag stats, I did read summaries of lots of other incidents in which mechanically successful deployments still resulted in full burial. Airbags drastically reduce the incidence of full burials, but they still happen sometimes.
In this case, any victim entrained by this avy all the way down onto the flats was probably hopeless give the amount of snow. The only entrained survivor (partially buried, with no beacon signal) seems to have gotten hung up higher on the slope (perhaps some sort of bench?), although another victim up there was fully buried and died, apparently b/c of trauma according to the report.
Airbags do increase the speed of the victim when entrained, as measured by the few controlled tests that have been conducted. This is probably because the snow higher up in the avalanche is moving faster, which is exactly where the airbag puts the victim. So, perhaps the airbag increased the chance of the victim ending up further down the slope (in the massively deep and deadly debris down there), although that’s 100% conjecture. Plus the 20% survival rate for the non-airbag clients of the airbag-equipped guide is not exactly encouraging...
Ironically, the widely credited airbag save in the Feb 19 Stevens Pass avy might have been pure luck instead. The “safe” regrouping location was poised above a horrible terrain trap, and all four fully entrained victims were taken 2400 *vertical* feet through rock outcrops, trees and other obstacles. The three fatalities were fully buried, but might have died from trauma anyway. The airbag skier was partially buried, with a 10-minute extrication. Although this does seem like a perfect “natural experiment” with three non-airbag skiers dead and the only airbag skier alive, given the terrain dangers, the airbag might have had nothing to do with survival (even though overall airbags definitely do enhance survival odds).