Analysis of Fatal Avalanche Faults Guides' Decisions

Two months after the deadliest avalanche in modern California history, a new analysis by leading US experts questions the decisions by the guides to lead such a large group through dangerous terrain during avalanche warnings. The backcountry skiers were traveling in a tightly packed line, when the tour leaders with Blackbird Mountain Guides should have spaced them out to reduce the risk, according to the final report prepared by the Sierra Avalanche Center and published Saturday on the National Avalanche Center site, per the AP. Nine backcountry skiers were killed by the avalanche Feb. 17 in California's Sierra Nevada when a massive wall of snow plunged down a slope near Lake Tahoe. Six others survived.

"Exposing only one person at a time to avalanche terrain is an accepted best practice for backcountry travel," the report said. "Analysis of past avalanche accidents has indicated that larger group sizes (4 or more people) have higher chances of being caught in avalanches." The report also noted that several members of the group wore avalanche air bag backpacks, but none of the lifesaving equipment deployed during the tragedy. Blackbird said Monday that an investigation is ongoing. "The report does not reflect the full scope of what transpired and does not include all of the facts and information currently under review," the company said in an email, adding that it is cooperating with authorities and will release more information when it's confirmed.

The report said the group of 15 was traveling through the potential path of an avalanche near Castle Peak following a period of intense snowfall when a slide was likely. The avalanche center has no enforcement powers. Its reports typically provide safety guidance. The Nevada County Sheriff's Office is conducting a criminal investigation, and state workplace regulators are investigating the company's decisions leading up to the avalanche. One avalanche expert told the AP that in this case, keeping the group together while traveling through safer terrain made sense, given the poor visibility and the risk of people getting lost. The report pointed out that many details aren't known, per the Reno Gazette-Journal, such as the avalanche's exact characteristics.