Detailed Accident Report

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Date: 2000-12-29
Submitted By: BTNFAC
Place: Upper Middle Piney Creek
State: WY
Country: USA
Summary: 1 snowmobiler caught, buried, and rescued by own group

Observation provided to the Bridger Teton National Forest Avalanche Center on 1/3/00

Subject: Avalanche Observation

Date: Wed, 3 Jan 2001 11:24:39 -0500 (EST)



Time and date of observation: Approximately 3 PM, Friday December 29, 2000 Date and time of avalanche event: Approximately 2 PM, Friday December 29, 2000. Member of party placed 911 call at 2:11 PM. Location of avalanche and name of slide path: T30N, R116W, Sec. 14, Upper Middle Piney Creek, Bridger-Teton National Forest, Big Piney Ranger District, Big Piney, WY Type of avalanche: Combination of Hard Slab and Soft Slab. Majority came down as Hard Slab with resulting debris field approximately 20 feet deep. Elevation of avalanche path start zone: Approximately 10,500 ft. (3200 meters) Estimated width and running length of avalanche: Approximately 1400 ft in width. Length not reported. Reported as entire bowl slid from top to bottom, length of this bowl is approximately 1000 feet. Aspect of avalanche path: East Size of avalanche (1 to 5 with 5 being full path): Reported to be a 4 plus by Tip Top SAR. Reported by party members that this was the largest avalanche observed by them in the Wyoming Range and that they had never seen this bowl slide in the last eight years. Triggering mechanism of avalanche event: Snowmobiles. Five (5) snowmobilers had played in bowl area then departed high to the south for Cheese Pass. One (1) snowmobiler returned north from Cheese Pass and came down bowl from top towards Middle Piney Lake. Remaining four (4) snowmobiliers returned to north low in single file approximately 50-100 yds apart. The crossed lower portion of bowl and last two (2) snowmobilers were caught. Avalanche involved entire bowl starting at north end and proceeding south. Avalanche started at old snowmobile track on north end. Were people caught in avalanche?: Yes. Two(2)persons were caught in avalanche. Second to last person in party of four (4) crossing bowl was caught in edge of avalanche, he was able to remain on surface. The last person crossing bowl was totally engulfed.

Were people buried in avalanche?: Yes. One(1)person was buried. The last person in the party of four (4) crossing bowl saw person in front of him being hit by avalanche. Victim attempted to turn uphill (west) into avalanche to ride over it. Avalanche washed out front end of snowmobile (skies) and victum was thrown from machine. He swam as hard as he could and was able to remain on the surface. As the slide stopped he stopped swimming too soon and was buried approximately 2 feet (head). Depth of crown face of avalanche at deepest place (was old snow involved?): Approximately 5 to 7 feet at middle of bowl, at south end of bowl it was 2 feet and at north end it was 3 feet. Bed surface upon which avalanche occurred: Dirt/ice. Weather conditions at time of observation: Dusk, clear, wind approximately 20 MPH, temp. 20-25 degrees F. Additional comments: Victim and two other members of party were members of Tip Top SAR and trained in avalanche conditions and rescue. Avalanche beacons were worn (Pieps with 457 kHz). Victim stated snow conditions were stable. Victim was buried approximately 15-20 minutes. Search with Pieps was started within 5 minutes of avalanche. Three hotspots were found and victum found at third spot with avalanche probe. Victim was wearing an open face helmet and was able to place hand in front of mouth prior to avalanche setting up to make breathing pocket. Snowmobile was partially buried and victum was located 4 feet from machine. Victim was examined by EMT's on scene and cleared.