- Location: Peter Barker path, near Aspen Mountain
- State: Colorado
- Date: 2015/02/23
- Summary Description: One skier caught, buried, and killed
- Primary Activity: Sidecountry Rider
- Primary Travel Mode: Ski
- Location Setting: Accessed BC from Ski Area
- Caught: 1
- Partially Buried, Non-Critical: 0
- Partially Buried, Critical: 0
- Fully Buried: 1
- Injured: 0
- Killed: 1
- Type: SS
- Trigger: AS - Skier
- Trigger (subcode): u - An unintentional release
- Size - Relative to Path: R2
- Size - Destructive Force: D2
- Sliding Surface: O - Within Old Snow
- Slope Aspect: W
- Site Elevation: 9990 ft
- Slope Angle: 38 °
- Slope Characteristic: Sparse Trees,Gully/Couloir
The avalanche was a soft slab, unintentionally triggered by a skier, small relative to the path, large enough to bury and kill a person, and broke into old snow layers (SS-ASu-R2D2-O). The avalanche released on a below-treeline slope (9,990 feet) that faced west-northwest. The avalanche broke at the bottom of an 11 cm thick layer of faceted snow grains, 1 to 2 mm in size with a Hand Hardness of 4F (four fingers). This weak layer was approximately 20 to 50 cm feet below the snow surface, and below a slab comprised of recent storm snow. The overlying slab had a Hand Hardness of 4F (four fingers) near the snow surface and stiffened slightly to 4F+ (four fingers plus) near the bottom of the slab. The crown was 20 feet wide at the highest point but widened to about 60 feet after traveling a short distance. The average height of the crown face was 35 cm and the maximum height was 50 cm. The slide ran 630 vertical feet. The slope angle in the start zone ranged from 38-40 degrees. The slope angle in the track was between 30 and 35 degrees and the alpha angle for this side was 31 degrees.
After a stormy start to the winter, the mountains around Aspen endured a prolonged period of dry weather between January 1 and February 15. During that interval, the Aspen Mountain Ski Patrol (AMSP) recorded just 18 inches of snow and 1.17 inches of Snow Water Equivalent (SWE) at the top of Aspen Mountain (1 mile southeast of the accident site). The weather pattern shifted in mid February, and two storms the week prior to the accident produced about 22 inches of snow and 1.66 inches of SWE. Six inches of snow fell during the first storm (February 16-17); the second storm (February 21-23) produced 16 inches of snow and ended on the morning of the accident. The second storm was relatively cold and windless, with high and low temperatures of 19 F and 7 F, respectively. Winds shifted from west to southeast during the three days. The average wind speed for each 24 hour period (ending at 9:00 AM) was between 4 and 7 mph.
At 9:00 AM on the morning of the accident, AMSP reported overcast skies, light snow (S-1), light winds from the southeast, and an air temperature of 19 F. By 2:00 PM, the clouds had broken and temperatures had warmed to 26 F. Winds remained light but had backed to the north and then west. The February 21-23 storm snow had settled from 16 to 13 inches during that five-hour period.
The prolonged mid-winter dry spell left backcountry slopes around Aspen Mountain with an atypically shallow snowpack. The snow cover on many southerly slopes had melted away. On slopes that received less direct sun, the near-surface layers of the snowpack consisted of a variety of faceted crystals and melt-freeze crusts. The faceting wasn't as pronounced as it might have been with colder temperatures, so the snowpack generally remained supportable on shady aspects. By mid-February, most of the layers in the snowpack on shaded slopes had a Hand Hardness of 4F (four finger) with some F (fist) hard layers near the ground. Several early-season weak layers had become indistinguishable from the layers above and below them. The avalanche danger was rated Low (Level 1) below treeline for the first half of February.
The mid-February storms initially did little to change stability of the snowpack. The six inches of snow recorded on February 17 did not form a cohesive slab and the few avalanches that people triggered in the backcountry were small because the slab remained relatively soft. On Saturday, February 21, stability tests did not produce consistent propagation on easterly and northerly backcountry slopes around Aspen Mountain, and few shooting cracks or collapses were observed. At that point, the load on the recently-buried faceted layers was about a foot of snow and less than an inch of SWE. The avalanche danger on below-treeline slopes was rated Moderate (Level 2).
Conditions had grown more dangerous on February 23 with the addition of another six inches of new snow and 0.625" of SWE. The recent snow settled quickly as the day warmed, and numerous skier-triggered slides were reported from easterly and northerly slopes in the backcountry around Aspen Mountain, including some remotely-triggered slides. A large natural avalanche was reported in McFarlane's Bowl around midday. These broke on the faceted crystals that were buried by the mid-February storms.
Events Leading to the Avalanche
Two skiers (Skier 1 and Skier 2) met at the top of Aspen Mountain shortly after 1:00 PM on February 23. Both had already been skiing at the ski area for several hours. Skier 1 had been skiing inside the ski area boundary, and Skier 2 had made solo descents of two popular backcountry runs on the east side of Aspen Mountain. Skier 1 immediately suggested skiing the Peter Barker run (the site of the accident). Skier 2 was reluctant because he was not carrying avalanche rescue gear. After some discussion, the two skied to Skier 1's locker at the base of the mountain, where they retrieved a second beacon, shovel and probe.
At about 2:00 PM, the pair contacted AMSP in patrol headquarters at the top of the mountain. AMSP reports alerting them to fresh slides in the backcountry adjacent to the ski area. Skier 2 reports that the beacon checker at the door of the building showed that both of their beacons were transmitting. They left the patrol building and made their way to the top of Ruthies lift. There they looked down the main run into Ophir Gulch, where they saw four snowboard tracks from that morning. They interpreted that as evidence of stability, so they continued a few hundred feet to the entrance for Peter Barker.
The pair left the ski area boundary and entered a stand of conifer trees on the skiers' left side of an open, west-facing slope which can be a start zone for avalanches. They worked their way down about 600 vertical feet through the conifers and some stands of aspen trees. Midway down they crossed an old road bed. Later, the first rescuers to the accident saw the crown of a small slab avalanche at this point as they approached, but it is not clear whether Skiers 1 and 2 triggered the slope or saw the crown. At some point during their approach Skier 1 dug briefly into the snow with his shovel. They stopped at a spot above where the trees open into a long, steep, narrow gully. They discussed how to enter the slope and who would ski first.
Skier 1 entered the slope from conifer trees on the skier's left. Skier 2 was standing on a flat spot slightly above and to the right of Skier 1. After Skier 1 made two or three turns, Skier 2 saw the snow fracture about 10 yards above Skier 1 and approximately at the same elevation as his own position. Skier 2 yelled as loud as he could, but Skier 1 continued skiing down. The fracture broke across the slope, starting on the skier's left side. Skier 2 yelled "Go Left!" three times, but Skier 1 didn't appear to hear the yells. The moving snow caught up with Skier 1 on his fifth or sixth turn and swept him around a corner into the main gully and out of sight of Skier 2.
Skier 2 followed the debris down the avalanche path, as it seemed like the safest route. Roughly a third of the way down the track he found a ski and called 911, who connected him to AMSP dispatch at patrol headquarters. AMSP received this call at 2:50 PM, contacted the Pitkin County Sheriff, and began organizing patrollers for a rescue. Dispatch also contacted Aspen Highlands Ski Patrol (across the Castle Creek Valley) and requested a spotter to observe the site.
After calling for help, Skier 2 took out his beacon but got no signal. Skier 2 continued down and found a second ski near the toe of the debris. Skier 2 zigzagged back and forth across the debris but did not get a signal, despite turning the beacon on and off several times. Skier 2 moved up to near the lower ski and found a ski pole strap around a small aspen tree but this clue did not lead to Skier 1.
At 3:12 PM, a hasty team of four from AMSP left the ski area boundary and started following tracks down Peter Barker. The team included a paramedic. At the same time, the spotter at Aspen Highlands reported seeing debris in the gully and, a few minutes later, a person moving back and forth over the toe of the debris. At the crown of the slide, the rescue party split into two pairs. The first two rescuers continued down while the other two waited as backups. AMSP dispatch had two additional phone contacts with Skier 2 during this time. They asked him to move to a safe location and talked Skier 2 through turning his beacon off as rescuers approached.
Rescuers 1 and 2 reported finding the upper ski in the path at 3:26 PM and a beacon signal at 3:31 PM. When Rescuer 1 got a reading of 0.5 m, Rescuer 2 started digging. Rescuer 2 uncovered Skier 1's hand on the second shovel strike. Skier 1 was fully buried 25- 50 cm below the snow surface. He had one ski pole with him. The strap was still around his wrist and the pole was completely buried. At 3:35 PM the rescuers reported no response from Skier 1 and began first aid and basic life support.
Rescuers 3 and 4 skied down to the site and Rescuer 3, a paramedic, took over first aid. Three additional rescuers left the ski area at 3:40 PM with a toboggan and additional first aid and rescue equipment. The rescuers ended resuscitation efforts at 5:02 PM.
Because of fading daylight and numerous obstacles in the remaining 1000 vertical feet to the road, the rescue team chose to postpone the body recovery until the following morning. They packaged and secured Skier 1 in the toboggan and all seven rescuers and Skier 2 left the scene at 5:20 PM. Volunteers from Mountain Rescue Aspen climbed to the site the following morning, reaching Skier 1 at 6:40 AM. They returned to the Midnight Mine road with Skier 1 shortly thereafter.
The Peter Barker run leaves the ski area boundary at 10,600 feet, just below the top of the Ruthies lift. It descends about 2200 vertical feet in a drainage that is unnamed on USGS topographic maps but which is locally known as Ophir Gulch or Keno. The run ends on the Midnight Mine road, where people often have a taxi waiting to shuttle them back to the town of Aspen. Other serious avalanche accidents have occurred in Ophir Gulch in the past 20 years. One in 1998 in Peter Barker resulted in a fatality and a second in 2010 in the Ophir Trees resulted in serious injuries.
Skier 1 and Skier 2 had skied together regularly for 15-20 years. They had skied the Peter Barker run together a minimum of 15 times and had established a route they typically followed. Skier 1 had skied it on numerous other occasions and often led others there. Familiarity with the terrain and the presence of other ski tracks on a nearby slope gave the group some degree of confidence that entering Peter Barker was a reasonable decision on the day of the accident. However, these factors can also serve as heuristic traps that lead people to expose themselves to more avalanche danger (McCammon, 2002).
Skier 2 found himself in the very difficult position of being the sole rescuer. He called 911 early in the rescue effort and was able to move down the path checking surface clues and making sure they were not attached to Skier 1. He was unable to find the signal from Skier 1's avalanche beacon, and therefore unable to complete a beacon search.
Once help arrived, rescuers quickly found the signal from Skier 1's avalanche beacon. They pinpointed his location and easily extricated him from the shallow burial. Skier 1 sustained some injuries during the avalanche, but he was buried for at least 45 minutes and the Pitkin County Coroner later ruled the cause of death as asphyxia.
The likelihood of surviving a full avalanche burial is closely correlated with burial time. Survival rates decrease precipitously the longer a person is buried. A recent study of avalanche accidents in Canada and Switzerland shows that close to 90% of avalanche victims survive a burial of 10 minutes or less, while for those buried 21 to 35 minutes only 24% and 44% survive (Canada and Switzerland) (Haegeli et al. 2011). Chance also plays a role, because some people do not survive short burials while others survive hours under the snow. Although not getting caught in an avalanche is the best chance of returning from a day of winter recreation, a quick and effective companion rescue can increase your odds when something goes wrong.
Figure 12: Fracture line profile.