Detailed Accident Report
Submitted By: Craig Gordon, UAC
Place: Seeley Canyon; Wasatch Plateau
Summary: Snowmobiler survives hour long burial
FOREST SERVICE UTAH AVALANCHE CENTER AVALANCHE ACCIDENT REPORTING FORM
2242 West North Temple, SLC, UT 84116 t: (801) 524-5304 f: (801)
524-4030 e: UAC@avalanche.org
Investigation completed by: Craig Gordon, Avalanche Forecaster, FS Utah
Avalanche Center, Salt Lake City, Utah
Date of Investigation: March 24, 2001
I. General Information
1. Date of accident: March 24, 2001
2. Time of Accident: Approximately 11:05
3. Exact Location: Seeley Canyon; Wasatch Plateau
4. Fatalities: 0
Victim: Jeff Braithwaite, 38 years old.
5. Eyewitnesses: Relatives
6. Damage to vehicles, building, lifts, etc.: None
I. Accident Summary
A party of 5 snowmobilers left the Miller Flat Trailhead and headed
south towards Seeley Canyon. Two snowmobilers, Jeff Braithwaite and his
son, were ?high-marking? a slope. The son was about mid slope and the
father above him when the slide released. The son was able to outrun the
slide, but his father was caught and buried. The son remained at the
scene and began probing, while the other three party members returned to
the trailhead to retrieve shovels and notify Search and Rescue with a
cell phone. An outsider, who was equipped with a beacon, shovel, and
probe, and knew the terrain well, overheard the commotion and raced to
the scene. Upon arriving he questioned the son as to the areas he had
probed and began probing in the opposite direction. At that point
additional searchers arrived on the scene and they began to organize a
hasty search. Someone thought they heard a voice from underneath the
partially buried sled. They began moving the debris from around the sled
and discovered the buried rider. Jeff was buried for an hour, was very
cold, had sustained minor injuries to his shoulder and leg, and was
flown from the scene.
II. Weather and Snowpack Data
This winter the snowpack on the Wasatch Plateau has been unusually thin
and weak. An initial stormy period in early November created an early
season snowpack which subsequently weakened during long spells of clear
weather in early December, late December, and in early January. Although
the region did experience a good slide cycle in mid December, a weather
pattern characterized by small storms did not produce another widespread
avalanche cycle to really clean things out. Throughout the season our
advisories have hovered in the MODERATE and CONSIDERABLE ranges,
occasionally bumping into the HIGH category. Warm temperatures, cloudy
skies, and marginal refreezes for 4 nights prior to this accident had a
dramatically weakened the snowpack. Conditions were barely supportable
on March 23 below 9,800? on all aspects. Stability test in the snowpack
at this elevation failed while isolating the column. A solid, but
short-lived refreeze on the night of the 23rd did provide supportable
conditions until about 11:30 am on the 24th. The advisory issued for the
day of the incident described a generally LOW hazard in the morning,
increasing to MODERATE on all aspects steeper than 35 degrees as the day
progressed. A CONSIDERABLE hazard was given to areas with a weak,
III. Avalanche Data
1. Type of slide(s) (classification): HS-3-AS
2. Dimensions width: 500?
vertical: Approx. 600?
3. Crown height: Averaging 3?
4. Debris width: 750?
depth: 12-15? at its deepest
5. Other comments: The run out was a low angle bench.
IV. Terrain Data
1. Elevation at the crown: 10,000?
at toe: 9,400?
2. Aspect: ENE
3. Slope angle in degrees, starting zone: 40 degrees
toe of debris:
1. Alpha angle from toe to starting zone:
2. Vegetative cover (open, timbered, etc.): Sparsely timbered.
3. Shape of path (open slope, gully, etc.): Open slope with a couple of
trees in the middle of the path; the bed surface was a rock slab.
V. Conclusions and Recommendations
This slide ran close to the ground on the faceted snow developed early
in the season. Visible clues to instability, such as glide cracks and
roller balls, were apparent on the slope adjacent to the slide. It is
very unusual for an avalanche victim to be recovered alive after being
buried for a hour. Very likely, an air pocket was created by the
snowmobile. He was not wearing a beacon, though his son did have a
probe. Rather then keeping everyone at the scene to assist in the
rescue, the bulk of the party exited to gather gear and additional
assistance. This was about a 14 mile round trip.