Detailed Accident Report
Submitted By: Ron Johnson; GNAFC
Place: Lionhead, Near West Yellowstone
Summary: 1 snowmobiler caught, buried, and rescued wearing a tranciever
ONE SNOWMOBILER CAUGHT, BURIED AND UNINJUIRED,
NEAR WEST YELLOWSTONE,MONTANA
JANUARY 31, 2002
During the afternoon of January 31, 2002, a snowmobiler released an
avalanche. He and a partner were riding near Lionhead, which is about 15
miles (24 km) northwest of West Yellowstone, Montana. He got stuck
trying to climb a steep, 600-foot (180 m) hill. The avalanche released
about 400 feet (120 m) above him while he was trying to free his sled.
His partner witnessed the avalanche from a small ridge near the bottom
of the avalanche path.
Both riders wore avalanche transceivers and carried shovels. They stated
that they rarely rode on the same slope at the same time, which was the
reason only one person was on the slope. When the ?dust? settled, the
rider who witnessed the avalanche rode onto the debris. He didn?t see
any surface clues and commenced a beacon search. As soon as he turned
his beacon to receive, he acquired a signal. Within a few minutes, he
decided he was close enough to start digging. About ten minutes after
the avalanche, he had dug through about 5 feet of debris and struck his
partners helmet. The buried person, though unconscious was breathing.
The rescuer left the site for several minutes while he used a cell phone
to notify the authorities in West Yellowstone. He returned to the site
and spent another 10 to 15 minutes removing the remainder of the snow
that covered his partner. The buried person regained consciousness after
being buried for a total of about 20 minutes. He remembered being caught
in the avalanche and heard his partner searching for him before he
?blacked out?. He was buried lying on his side, perpendicular to the
slope and wasn?t injured.
The next day, I went to the site and talked to the people involved in
the incident. They were retrieving a snowmobile, which was buried under
5 feet (1.5 m) of debris, at the same elevation and 20 feet (6 m) from
where the rider had been buried. These guys were from Wyoming and had
ridden in this area during previous visits. They were experienced
The avalanche was about 500 feet (150 m) across and ran about 600
vertical feet (180 m). The crown was at 8400 feet (2520 m) in elevation
and was 2 to 4 feet (.6 to 1.2 m) deep. The avalanche using the U.S.
Classification was HS-3-AV-O. Using the Canadian Scale this was a size 2
to 3 avalanche. The avalanche fractured on a weak layer of faceted
crystals that formed near the snow surface during a cold, dry spell
around Christmas. The average slope angle of the bed surface was 37
In summary: A person is alive because his partner watched him ?highmark?
from a safe location, his partner carried and knew how to use the
appropriate rescue gear, and his partner did all ?the right stuff? to
facilitate a successful rescue.
Ron Johnson, Avalanche Specialist, Gallatin National Forest Avalanche
Center, firstname.lastname@example.org , 406-587-6984