Accident Report          Forest Service Utah Avalanche Center

 

Saturday, February 03, 2007

 

Pfeifferhorn – Two climbers caught, one reported as critically injured.

 

Accident Report by Drew Hardesty  2-3-07 8pm

 

Location:

The avalanche was on the southeast facing slope just beneath the east summit ridge of the Pfeifferhorn (large scale map) at approximately 11,000’.  The Pfeifferhorn sits along the Little Cottonwood/American Fork ridgeline at an elevation of 11,326 feet.  It is a common mountaineering and ski-mountaineering objective. 

 

Accident Summary and Rescue Summary:

The two 43 year old men were attempting to climb the east ridge of the Pfeifferhorn and triggered a small pencil hard wind slab on the steep southeast flank of the ridge.  While the avalanche was reported to be small, both were carried over 150’ cliff-bands onto the snow-slope below.  A rescue call came in at 1014 a.m., and the Search and Rescue teams with both Salt Lake and Utah counties responded, along with Wasatch Backcountry Rescue.  As strong winds precluded the initial use of aircraft, WBR teams skied in from the White Pine Trailhead, only to be met by other team flown in a couple hours later.  The rescue personnel were able to stabilize both men and sled them down to a safe landing zone on the Utah county side, where helicopters transported them down to a hospital in Salt Lake.  It is not known whether they carried any rescue equipment, had avalanche training or had called the avalanche advisory.

 

Avalanche Data: 

From photo observation and personal communication with rescuers, the new wind slab appeared to be 3-6” deep and 70-100’ wide, running 700’ vertically down the mountain.  The avalanche would be classified as a HS-AF-R2D1-I, a hard slab artificially triggered by a person on foot.  It is also likely that the new wind drift failed on a weak interface of low density snow or small faceted grains above a stout melt freeze crust.  Clearly, the danger from the avalanche centered on the steep mountainous terrain the two were in, rather than the overall size of the avalanche, similar to an event that killed a friend of mine climbing in the Canadian Rockies just last spring. 

 

Weather History: 

The Wasatch Range received 6-10” of new light density snow from January 30th-early February 2nd.  Densities were generally less than 8%.  Strong winds the evening of Feb 1st resulted in numerous Class 1 and Class 2 avalanches in steep wind drifted terrain, with most being less than a foot deep and 60 feet wide.  Sustained strong west to northwest winds allowed avalanche control teams at the ski areas and backcountry skiers to trigger similar avalanches on Saturday February 3rd as well.   The reported avalanches were generally class 1 or 2 (harmless to could potentially bury a person), and localized to steep wind drifted terrain.  No natural avalanche activity was reported during the day.