Avalanche Accident
Report
Sunday, December 14, 2008
Voodoo Wall, Canyons Backcountry – One member of a Five person ski touring party triggered slide, carried through trees, survived with serious injury.
Accident Investigation &
Report by Grant Helgeson and Drew Hardesty
Edited & compiled by Brett Kobernik
Location:
The avalanche was triggered just above Wall of Voodoo, skiers right of “Squaretop,” (SQ.T) a popular N facing slope near The Canyons ski area. The avalanche was triggered midslope by the victim, about 9,400’. The slope terminates at Red Pine lake, just outside of The Canyons ski area. See the aerial view.
Terrain, Accident and Rescue
Summary: (Click HERE
for photos)
A party
of 5 expert skiers left the Canyons ski area just before noon. As there were no backcountry gates open at
the time, the group “ducked the rope,” to leave the resort. The group warmed up with a few laps on “The
driveway” an E-NE facing backcountry ski run.
One member of the group assessed the snow with a few hand-pits while
lapping this slope. After tracking up
the driveway, the party debated exploring more terrain versus calling it a
day. It was suggested that the party
explore the terrain around SQ.T. The
group then toured around the SW side of SQ.T, eventually gaining the ridge that
flanks SQ.T to the skiers right. The ridge runs NE before petering out next to
Red Pine lake.
The group discussed descending the ridge down to the summer road that
borders Red Pine lake.
Staying on the ridge was the “safest” way to descend. The first skier went down the ridge and then
went skiers left into the NE facing slope just below the “Wall of Voodoo.” The second skier dropped just left of the
first skiers track, enticed by a beautiful, untracked & steep slope. This deviation from the plan nearly cost the
young man his life.
The
three remaining skiers on the ridge saw the avalanche break behind the second
skier. One member commented that he saw
the slab flow up and over the stock wall.
The three skiers on the ridge began shouting and were getting a garbled
response from below. One of the skiers
on the ridge instructed everyone to switch their beacons to receive and
immediately began descending the slide path.
It was immediately apparent that the avalanche had carried the victim
through a stand of rugged alpine pine.
The
first skier was not caught in the slide, and was already attempting to free the
victim when the skiers who had been on the ridge arrived at the victims
location. The victim was wrapped abdomen
first around a tree, another tree pinning his back in place. Blood was present, and it was clear that the
victim had sustained serious trauma during the avalanche.
While
the group made a serious lapse in judgment skiing the
slope, they did execute a great rescue.
The tree pinning the victim was removed, as was the snow surrounding his
torso. Next they constructed a makeshift
stretcher and alerted emergency response teams via cell phone to their
predicament. The emergency teams
informed the group that they would need to get the victim down to Red Pine lake to meet outside help.
One member of the group broke trail while the other three did their best
to support & move the victim. The
party lowered the victim some 200 vertical feet to the lake where they met
Canyons ski patrol who then took control of the situation and loaded the victim
& group into the waiting snowcat. When the snowcat
reached a suitable heli landing location, the victim was loaded into the
medical helicopter and flown to the local hospital. He arrived at the hospital hypothermic with a
broken pelvis, vertebrae as well as other injuries.
The
Avalanche Data:
The
avalanche is classified as: SS-ASu-R2D2-O
Meaning
it was a soft slab, skier triggered size 2 avalanche (could bury injure or kill
a person), that ran to the middle of the runout zone, and failed in old
snow. The slope inclination at the crown
was 42 degrees & N-NE facing. The
slide was approximately 60’ wide and ran 400’ down the slope. The crown averaged 20” in height. The slab broke below an ice lens in large
grain facets. The 2.5 mm facets were not
cohesive, but, behaved as a soft slab none the less.
The
avalanche occurred in complex terrain where a slight deviation from the ridge
can spell disaster. The
Weather and Avalanche History: (Click HERE for a snowpit profile)
The
Comments:
The group was composed of 5 expert
skiers. Avalanche skills/education among
the group ranged from a former ski patroller to no formal avalanche education
with most of the group having attended a level 1 class. Unfortunately, only one member of the group
had read the avalanche forecast in its entirety. Had the group known of the nearby large
avalanches the day before the accident, would they have still skied the
slope? It’s tough to say.
It’s always easy to see what went
wrong in hindsight, and this accident is no exception. Most of the group had skied this terrain
before, falling into the Familiarity trap.
Before descending the ridge, the group had committed to the idea of not
turning back aka, the Commitment heuristic.
It’s likely that there was some Social Facilitation at play as two
members of the group had more backcountry experience than the other three. One member of the group states that he did
not feel good about the decision making going on, but, fell victim to the
Expert Halo heuristic and didn’t voice his concerns. I invite anyone interested in these Heuristic
Traps to check out Ian McCammon’s work in the
area. All the snow science training in
the world will not keep you out of avalanches when these powerful heuristic
forces are at work. This was an expensive
lesson for the 4 men and one woman involved, especially the victim who remains
in the hospital with numerous serious injuries.
