Detailed Accident Report
Submitted By: GNFAC; Schmidt
Place: Yellow Mountain near Big Sky, MT
Summary: 1 skier caught, buried, and killed
***OFFICIAL REPORT FROM GNFAC***
YELLOW MOUNTAIN AVALANCHE FATALITY
03 March 2007
One skier was caught and killed in an avalanche that occurred on Yellow Mountain near Big Sky, Montana. The avalanche released on a wind-loaded slope with a southerly aspect. The crown was 2 feet at its deepest point, had a slope angle of 39 degrees, fractured 75 feet across, and ran 2070 vertical feet. The victim, who triggered the avalanche on his second turn, was caught and carried over a cliff and down through a rocky chute. Cause of death was blunt force trauma. US classification of the avalanche is SS-AM-R2-D2-O.
This area received snow every day for 9 days prior to the avalanche. Total snow accumulation during this period was 36 ? 42 inches. Of this total accumulation, 6 - 10 inches fell in the 48 hour before the avalanche, which occurred on 3 March. Strong north winds (25 ? 40 mph) blew the night of the 1st and into the morning of the 2nd. Temperatures were seasonal, with nighttime lows below zero and daytime highs in single digits.
21 year old Ben Richards and a partner skinned to the top of Yellow Mountain intent on skiing a steep, south-facing gully locally name ?The Titanic Chute?. The top of the chute is 38 ? 42 degrees, but quickly flattens into the mid-30?s before making a sharp right-hand bend half way down. Immediately after the bend is a steep cliff which terminates in a narrow, rock strewn gully. The victims partner skied a short distance onto the slope to test the stability. He stopped just above the point where the slope rolls over to steeper angles. When nothing happened, Ben entered the chute. On his second turn he initiated the fracture which propagated 75 feet across. The fracture depth was 1 ? 2 feet deep. He was caught and carried over the cliff mid-track. The avalanche continued down the gully for another 1000 feet slope distance before coming to rest. The victim was buried 4 feet deep near the toe of the debris.
The avalanche was triggered at approximately 12:00 in the afternoon. Ben?s partner skied to the bend in the chute and then made his way up and over a rib into adjoining terrain. He was able to negotiate this steep, rocky slope and reach the burial location approximately 30 minutes after the avalanche released. He located and dug up the victims who had suffered significant trauma. The victim had no pulse and was not breathing. The partner left the scene and went to a near by house to report the incident. Search and Rescue was called out at approximately 1:00 pm. Big Sky SAR responded and was on-scene within an hour. The Gallatin County Helicopter Rescue Team was also dispatched and the helicopter was used to short-haul the body from the scene. The Gallatin County Deputy Coroner ruled that the victim died from multiple blunt force trauma.
A layer of small-grained facets formed during a short period of clear weather the second week on February. This layer was subsequently buried by almost continuous snowfall over next several weeks. Strong north winds 36 hours prior to the event deposited a pencil hard wind slab in the starting zone of the avalanche path. Compression test preformed during the investigation produced clean shears with moderate force on the weak layer of facets.
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Gallatin National Forest Avalanche Center