AVALANCHE, FALL ON SNOW – SKI MOUNTAINEERING, IGNORED RECENT AVALANCHE ACTIVITY, MISJUDGED SNOWPACK, USING SKI- CUTS TO ESTIMATE STABILITY, TRYING TO STICK TO A SCHEDULE

Alaska, Mount McKinley, West Buttress, Rescue Gully

On June 25, a climber (34) set out from 14,200-foot camp with her three teammates, intending to ski a line above 17,200-foot camp known as “Thunderbird”. As the team was climbing on the ridge between the fixed lines at 16,200-feet and the 17,200-foot camp, they became concerned with weather conditions up higher on the mountain. They arrived at 17,200-foot camp in high winds. They talked about the conditions and decided not ski “Thunderbird” but to ski down from 17,200-foot camp via the Rescue Gulley instead. The team worked their way down through the steep entrance of the Rescue Gulley and regrouped at the mouth of it to dig a snow pit and evaluate both snow conditions and the terrain below.

Based on their analysis of the snow conditions, the team decided to continue into the open terrain below the Rescue Gulley with plans of skiing one at a time. Being one of the stronger skiers, the climber in question was the first to go. She skied approximately 500 meters straight down, where she triggered an avalanche that swept her off her skis. At first, she slid approximately 200 meters trying to self-arrest and stay above the debris, but after sliding, she began to tumble another 100 meters before coming to a stop on top of the debris. Her initial assessment of herself was that she had a small laceration on the top of her head and an injury to her left knee. She was unable to ski out, so she called the National Park Service for assistance.

About 1830, at the 14,200-foot camp, an NPS Ranger and four patrol volunteers observed the climber begin her ski descent and trigger the avalanche she was caught in. The ranger set up a spotting scope to observe her after she stopped tumbling to see if she was in need of assistance. Before she had called, the ranger observed her stand up after the event and try to sideslip on her skis down the debris field. It was apparent that she had some type of lower leg injury, which led the ranger to have his patrol volunteers gear up as a hasty team and stand by. At 1845, there was an FRS radio call from a climber at the base of the fixed lines who had voice contact with the injured climber. The contact person stated that she was asking for assistance and informed the ranger of the climber’s injuries.

The ranger organized four climbers from the 14,200-foot camp to assist his patrol volunteers in a lowering from the patient’s location to the 14,200- foot camp. She was directed to stay where she was while a rescue team was organized. The rescue team traveled up the debris field created by the avalanche in order to stay off of other potentially loaded slopes surrounding the patient. When the rescue team arrived on scene, a medic performed an initial assessment, which confirmed a laceration on top of the head that had stopped bleeding, and an injury to the patient’s left knee. She was packaged in a sleeping bag for warmth and lowering began with the Cascade Litter at 2120. The lowering team conducted three 200-meter single rope pitches on moderate/low angle terrain to get the patient down to the medical tent at 14,200-feet. Here she was reassessed. It was determined that the injury to her knee was not conducive to skiing down the mountain under her own power. At 0900 on June 26, the park helicopter was called to fly her to base camp the next morning, where she waited to meet up with the rest of her team who were skiing down from the 14,200-foot camp.

Analysis

Skiing off of the West Buttress route and in and round the 14,000-foot camp has gained popularity over the last few years. In 2007 a group of friends based out of the 14,200-foot camp for a 14-day trip were able to ski many classic lines as well as a few first descents. Their trip was characterized by a series of storms that created stable conditions favorable for skiing. This year Denali was again the goal of at least eight expeditions focused on skiing big lines. The 2009 skiing conditions were much different and were characterized early on by icy hard-pack snow and unstable wind slabs toward the end.

The most significant components in this incident were ignoring the recent avalanche activity, misjudging the spatial variability of the snowpack, underestimation of scale of the terrain, and team dynamics. All were very experienced skiers with significant collective knowledge of avalanche formation, mitigation, and snowpack stability. Storm totals are difficult to calculate with the limited availability of wind-sheltered areas, but best estimates were approximately 18 inches with moderate wind transport. There had been a climber-triggered avalanche the day before on the fixed-lines adjacent to the descent line. This size two avalanche slid on an early season ice layer with a crown height of the storm total of approximately 18 inches. The skiers were dusted by the powder cloud from this avalanche, so they were well aware of the instabilities in the snowpack.

When the skiers entered into the gully, they used ski cuts as a method for testing the stability of the snow. They found no instabilities and much less snow in the gully. This is common for the top of the Rescue Gully because of the way the wind funnels through the terrain. Ski cuts, although effective in soft slabs and loose snow, lose their effectiveness as soon as they are not penetrating to the bed surface. Ski-cutting large slopes with high consequences is a dangerous practice that will in time catch even experts off guard.

Their snow pit showed no significant instabilities and was dug at the bottom of the Gully as the slope fans out. The terrain changes from a small more easily managed gully to a large, unsupported, open slope with no safe areas. What they failed to recognize was that their snow pit did not represent the snowpack on a subde, wind loaded, convex roll lower on the slope. Their methods for testing for instabilities, ski cuts, and their snow pit were un-representational of the larger more dangerous slope below. Because their tests showed stable snow with no wind slab, they assumed the entire slope to be the same and did not take into account the high degree of spatial variability represented on this slope.

They also underestimated the size and consequences of the terrain. From the 14,200-foot camp and their climb up to the fixed lines, they had identified the subtle convex roll on the slope and agreed to stay away from it. Once the injured climber exited the gully and the slope widened, she indicated that she lost track of her position on the slope and could not tell where the convex roll was. As she committed to the slope, the snow changed from loose, manageable snow to a supportable wind slab.

There were obvious signs of instability. The terrain is characterized as a large, open, unsupported slope with a small convex roll, and because of the elevation and wind, a high degree of spatial variability. All of these are red flags that when the team members were asked later, each recognized them at some point. So why did they over look these obvious clues? All members of the team were highly motivated expert skiers and wanted to ski. The snow conditions up until this storm cycle had not been good and now it was excellent. A few days before, a team of skiers had successfully skied the Rescue Gulley early on in the storm. But for this team, it was the last day of their trip and they had not skied any of their big objectives yet. The schedule, therefore, dictated their attempt.

(Editor’s Note: While the objective for this team was to ski on a big mountain, this incident fits the category of ski mountaineering because of the techniques and equipment required to get to and from the objective. We will decide on a case by case basis as to which incidents resulting from skiing the big and steep will qualify for this category.)