CAIC: Colorado Avalanche Information Center

2019/03/23 - Colorado - Black Mountain, east of Arapahoe Basin Ski Area

Published 2019/03/30 by Mike Cooperstein, Spencer Logan - Forecaster, CAIC

Avalanche Details

  • Location: Black Mountain, east of Arapahoe Basin Ski Area
  • State: Colorado
  • Date: 2019/03/23
  • Time: 9:00 AM
  • Summary Description: 4 backcountry tourers caught and carried, 5 injured
  • Primary Activity: Backcountry Tourer
  • Primary Travel Mode: Foot


  • Caught: 4
  • Fully Buried: 0
  • Injured: 5
  • Killed: 0


  • Type: SS
  • Trigger: AF - Foot penetration
  • Trigger (subcode): u - An unintentional release
  • Size - Relative to Path: R1
  • Size - Destructive Force: D1.5
  • Sliding Surface: I - New/Old Interface


  • Slope Aspect: SW
  • Site Elevation: 12600 ft
  • Slope Angle: --
  • Slope Characteristic: Gully/Couloir

Accident Summary

On March 23, 2019, two groups of three riders arrived at the Arapahoe Basin Early Rise parking lot. Both groups intended to climb and ride a couloir on Black Mountain, just east of the Arapahoe Basin Ski Area. The two groups bumped into one another in the parking lot and it turned out that they all knew each other. They discussed their plans for the day and decided to remain separate. One group of three would climb and ride a couloir locally known as “The Dog Leg” and the other group would climb and ride a couloir locally known as “S#@t for Brains”. 

They left the parking lot around 7:00 am and skinned through the ski area to reach Black Mountain. When they arrived at the bottom of the couloir they changed their plan and decided to stay together as a group of six. The full group consisted of  2 snowboarders and 4 skiers (1 female and 5 male). They decided they would bootpack up the couloir, gain the ridge, and then ride back down the way they came. They spaced out and began bootpacking up the couloir. 

They had reached an area that they described as “about three quarters of the way up the couloir just below a steep bulge”. Just before 9:00 AM they triggered an avalanche that broke about 10 feet in front of the lead climber. The avalanche broke about 18 inches deep and propagated the entire width of the couloir. 

Climber 1, the highest uphill, was hit by the avalanche and tumbled over Climber 2 who saw the slide coming and was moving out of the way. Climber 2 was not caught, but sustained a laceration most likely from the crampon of Climber 1. Climber 1 ended up about 600 vertical feet below, just uphill from the mouth of the couloir. He was on the snow surface and sustained minor lacerations. The avalanche swept Climber 3 off her feet.  She “was able to open her eyes, and saw periods of light and dark as she was swept underneath the snow.” She ended up on the snow surface about 50 vertical feet below Climber 1. She also sustained minor lacerations as well as some torn clothing and broken equipment. Climber 4 was able to get out of the way and did not sustain any injuries. Climber 5 was swept off his feet, but was able to stop after 40 or 50 feet. Climber 6, the last in the group, was knocked the farthest downhill and ended up on the surface approximately 700 vertical feet below where the avalanche first hit him. He sustained deep lacerations and needed to seek further medical attention. 

The group called Arapahoe Basin Ski Patrol to report the avalanche. They informed the patrol dispatcher that they could get out under their own power. The group was met by patrollers as they entered the ski area and they were taken to the base area for evaluation and medical treatment. They were eventually released to seek further medical care if necessary.

The group described themselves as experienced backcountry riders. They were all carrying an avalanche transceiver, shovel, and probe. Only one person from the group had ridden in this couloir before.

This was a soft slab avalanche. It was most likely triggered from the bottom of the slab by the first person in the group. It was small relative to the path, and if the group was not in steep confined terrain the avalanche would have been relatively harmless. It most likely released on the interface between the freshly drifted snow and the old snow surface beneath (SS-AF-R1-D1.5-I).


We are happy that nobody was seriously injured in this accident. We write these accident reports to help backcountry users learn and practice safer travel techniques not to criticize those involved in an accident. There are some important takeaways from this event. 

First, if you are traveling in an operating ski area it is important to stay out of closed areas. You should always exit a operating ski area through a marked backcountry gate. You do not want to inadvertently travel into an area where the ski patrol is doing avalanche control or set tracks that lead other people into trouble.

Second, it is always a dangerous proposition to expose more than one person at a time to avalanche terrain. If this avalanche was larger it could have resulted in multiple burials. If multiple people are buried or injured the complexity of the rescue and evacuation increases dramatically. 

Finally, as this group found out, it does not take a very big avalanche to knock you off your feet when you are in a steep, confined avalanche path. Even a small avalanche like this one resulted in a rough, dangerous, ride and most of the group sustained injuries. 

We would like to thank the Arapahoe Basin Ski Patrol for their help with this investigation.