Detailed Accident Report

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Date: 2004-02-28
Submitted By: SNFAC
Place: Apollo Creek, about 15 miles Northwest of Ketchum
State: ID
Country: USA
Fatalities: 1
Summary: Snowmobiler caught buried and killed

Snowmobile rider was highmarking a mostly east facing 30 to 50 degrees

slope/cirque at the head of the Apollo Creek drainage.

The rider was on the slope alone. He had been alternating highmarking w/a

fellow rider. When one rider got as high as he could the next would follow

his track and try to go higher. Each rider had taken 2-3 runs on the

slope. When one person was on the slope, the other would wait in a "safe"

location off to the side of the toe of the slope. Three other companions

were waiting farther off to the side and they were not involved in the high

marking

The rider triggered an avalanche at about mid-slope at the apex of his

high mark (he was beginning to turn across the slope) w/a reported crown

depth of about one foot. The fracture occurred on buried surface hoar

beneath one foot of new snow from 2/26

The snowmobile, rider and moving snow most likely triggered a deeper buried

surface hoar layer (2.5 ot 3 feet deep) seconds after the original

avalanche was triggered. The fracture propagated to the top of the ridge

on the deeper weak layer and triggered a second avalanche. The second

avalanche entrained the previously undisturbed upper half of the slope, hit

the original crown line and dug down and swept away the original bed

surface.

The rider and the snowmobile traveled through a group of trees (fragments

from the machine were found stuck in several trees)

The victim's companions located him w/their beacons in an estimated 10

minutes and extracated him from under 6 feet of debris in an estimated 25

minutes. He did not respond to CPR and showed signs of massive trauma.

The companions rode to the last seen point and searched downhill.

The victim was located about 25-30 feet down slope from his machine.

The machine's handlebars were barely visible on the surface and the

searchers saw them but proceeded uphill (on their machines) to the LSP and

then searched down.

The victim's companions left the body at the scene at about 5pm and rode to

the trailhead and notified authorities. The body was recovered w/a

helicopter the following day (Sunday 2/29)

The riders were using good travel techiniques but obviously underestimated

the instability (the Sawtooth Av Ctr had issued a special announcement to

the local media warning of the instability and the day's advisiory had a

special heads up for the snow machiners)

The victim was male, 29, from Kimberly, Idaho (80 miles south of Ketchum)