UDOT PLANNED AVALANCHE CLOSURES!!

Accident: Mt Aire

Observer Name
Hardesty and Hosford
Observation Date
Monday, February 7, 2011
Avalanche Date
Saturday, February 5, 2011
Region
Salt Lake » Parleys Canyon » Mt Aire
Location Name or Route
Mt. Aire
Elevation
8,400'
Aspect
North
Trigger
Skier
Trigger: additional info
Unintentionally Triggered
Avalanche Type
Hard Slab
Depth
10"
Width
90'
Vertical
800'
Caught
1
Carried
1
Buried - Partly
1
Injured
1
Accident and Rescue Summary

A party of two very familiar with the terrain were skinning up through the trees in the bowl. They were spread out following safe travel protocol. Climber's left had only weak snow, no slab. As the first skinner moved up and right to gain the ridge, he collapsed the newly formed wind slab (in the lee of the north/northwest ridge) above the faceted grains and it pulled out 10' above him.

Never caught how far he was carried, but he relayed that he was wrapped around a tree, lost a ski and suffered two broken ribs and a fractured tibial plateau. The two were able to self-evac with significant self-reliance and suffering.

By the individual caught, carried and injured -

"A bit of a rough ride after triggering a slide on the up track nearing the top of Mt Aire. Thankfully aside from some injuries all is well. The failure occurred on the new snow/old snow interface with wind loading being the culprit of the new snow. Even though the majority of the loading was happening on the south facing slopes enough had loaded to from a 6" slab that broke free about 10 feet above me. The fracture followed the ridge down for an undetermined distance. Just goes to show to that even some loading with no new snow can get things moving especially on solid crust. Thanks UAC for keeping us all informed."

Comments

Photo below is what we found high along the ridgeline on a test slope while accessing the accident site. New wind slab over the gray facets. Video below also describes the snowpack structure on Mt. Aire.

Comments

Hard slabs were forecasted due to the strong winds. They destroy the arms of the snowflakes and pack them tight into a hard slab. Soft slabs you ski or ridge through, hard slabs you stay above, as with the pic below.

Comments

The crown was 8-12" in depth, but continued propagating 400' down the ridgeline. I found the ski with the skin still attached perhaps 500' down the slope. Hard slabs have the propensity to pull out above you when you've perhaps collapsed a thinner part of the slab onto the failure plane below. This seems to have been the case as the two were skinning up the slope and moving into the thinner part of the 'lens' of hard slab. Heading up and into the slab, having it break above you, and skinning doesn't give you much of a chance to escape. Fortunately, the two were spread out enough so that only one was caught.

Comments

Looking down the slide path.

Video
Coordinates