Detailed Accident Report

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Date: 2001-03-24
Submitted By: Craig Gordon, UAC
Place: Seeley Canyon; Wasatch Plateau
State: UT
Country: USA
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,

shallow snowpack.

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?

length: 250?

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.