Avalanche Accident Report         

Forest Service Utah Avalanche Center

Pioneer Ridge Accident – Snowboarder caught, carried, and partially buried on Thursday, December 13, 2007

Accident site investigated by Craig Gordon and Evelyn Lees, report by Evelyn Lees.

Location:

The avalanche was on a slope off the east ridge of Pioneer Peak, which runs between Pioneer Peak and the Brighton Ski area boundary, in upper Big Cottonwood Canyon. The avalanche was on a steep northwest facing slope at 10,200’, below peak 10,321.

Accident and Rescue Summary:

A party of three snowboarders spent the morning boarding in area at Brighton Ski resort for 3 hours. After lunch, they rode up Crest lift and hiked out the Pioneer gate. The three had not called the Utah Avalanche Center forecast, but noted the posted UAC danger rating of ”MODERATE” as they left the gate. They were not carrying their beacons or shovels. They followed the boot track up to the top of sub peak 10,321. As they dropped into the initially low angle terrain, they dug a quick hand pit. As the terrain steepened, all three regrouped above a steeper break over. The first person dropped in 5 or 6 turns, when he heard a yell. The slope broke out under them all three of them. The lower person shot out right to some trees, getting out of the slide. The left most person was caught and carried as he attempted to move left. After a short distance, he was able to jam his snowboard against a clump of trees, and let the slide go by. The middle person went for the full ride, approximately 400 vertical feet.

When the two boarders on top realized their partner was missing, they made a quick plan. One called Brighton Resort for help, and then started searching the upper section of the slide path, checking out any piles of debris. The other focused on the lower debris, where he saw an odd shaped lump, then the hat of the 3^rd person, and some movement. The victim had one hand partially free, and was attempting to clear his face, which was partially buried. He was in a semi prone position, face up, head up hill near the surface, and feet, with board still attached about 4 feet deep. His two companions dug him out, and kept him warm until rescue came. He was sledded to Brighton base, taken by ambulance to the hospital, and released later that night.

Terrain Summary:

This popular terrain is accessed through a well signed backcountry gate at the top of Brighton’s Crest lift. The gate was opened for the first Saturday, Dec 8th, and the area was only lightly tracked. The area had not had early season traffic. The slope to the northwest off sub peak 10,321 is deceiving. It starts off as a gentle open slope with sparse trees that then leads down to much steeper, treed and rocky terrain with no lower angle options.

Avalanche Data: 

The avalanche would be classified as a HS-AR-R3D2-O, a hard slab avalanche artificially (and unintentionally) triggered by the snowboarders. The slope angle at the crown face was about 36 degrees, and the crown face was 2 ½ to 3’ deep. The slide measured about 80’ wide, and ran approximately 400 vertical. The path was open at the top, then narrowed and steepened to over 40 degrees as it ran through a shallow gully. The track had several stands of trees. The average angle from crown to toe of the debris was 38 degrees. The debris pile is estimated to be 6 to 7’ deep.

The slab varied from fist hardness at the surface to 1 finger harness just above a thin crust, which capped the weak layer of fist hardness 2mm facets. The total depth of snowpack was about 44”. (Click here for crown face profile)

Weather and Avalanche History: 

Early season storms in October created a snow pack of about 20” which was followed by dry weather. During this time, the October snow faceted, with a few ice crusts forming near the surface. Then several December storms added another 3 to 4 feet of new snow to the pack. This resulted in numerous natural and human triggered slides on steep, upper elevation northwest, north and northeasterly facing slopes in the Cottonwood Canyons, all failing on the October facets.

Observations:

The three boarders have some snowpack, terrain, and avalanche knowledge, but just did not quite put the pieces together that day. They owned beacons and shovels, had practiced with their beacons, but did not take them that day. They had attended several avalanche awareness talks. They dug a quick hand pit just off the ridgeline, but the location and/or depth did not give them the information they needed. They also had a plan of stopping at the steeper rollover, and descending the slope one at a time, but misjudged the terrain. However, when the accident did occur, their response was ideal – one person was able to get off the slab, another stopped using trees. They then rapidly organized and performed an effective self rescue, getting their partner out alive. With this near miss having a good outcome, it could be considered a good learning experience.