Ian McIntosh's 1,600-Foot Fall in Alaska's Neacola Mountains

On one of his first turns down a steep face in Alaska's Neacola Mountains, professional skier Ian McIntosh dropped into a trench he could not see, lost his footing and was swept away by his own sluff. He cartwheeled more than 1,600 feet (about 490 m) down the mountain in under a minute, and survived. Teton Gravity Research released the footage on 5 November 2015, and it remains one of the most watched ski crashes ever filmed.

What happened in the Neacola Mountains

McIntosh, known to friends as "Mac", was filming for Paradise Waits, Teton Gravity Research's 2016 ski and snowboard film. A few turns into the line he fell into an unseen trench about five feet (1.5 m) deep. "From there, my slough took over and there was no way to stop," he said. He lost a ski trying to get back on his feet, and the moving snow carried him tumbling down the face.

As he fell he pulled the handle of his avalanche airbag, to reduce the risk of trauma injuries as he cartwheeled down the slope. He came to rest at the bottom shaken but alive. TGR co-founder Todd Jones called it "the most terrifying crash I've ever seen."

Watch the fall

Where are the Neacola Mountains?

The Neacolas are the northernmost subrange of the Aleutian Range, in south-central Alaska west of Cook Inlet. They rise along the edge of Lake Clark National Park and Preserve, with its lakes and lowlands to the west and south. The highest summit, unofficially called Mount Neacola, reaches 9,426 ft (2,873 m). There are no roads or lifts: skiers and film crews reach the steep, glaciated peaks by ski plane or helicopter, which is why the range became a favourite for big-mountain ski films.

Sluff, avalanche airbags and steep skiing

Sluff is the loose surface snow that a skier sets moving on a steep slope. On its own it is usually small, but on a long, steep face it can gather speed and volume and knock a skier off their feet, which is exactly what happened to McIntosh. Big-mountain skiers learn "sluff management": they ski across the slope and let the moving snow run past them before turning back into the fall line.

An avalanche airbag is a backpack with a large bag, typically around 150 to 200 litres, that inflates within seconds when the skier pulls a handle. In a flow of snow, larger objects tend to rise to the surface while smaller particles settle, an effect called inverse segregation, so the bigger "package" of skier and airbag is more likely to stay on top. Airbags are designed to prevent burial and give some cushioning; they work best together with a transceiver, shovel, probe and good terrain choices. Ski steep Alaskan lines with an experienced guide or team: the scale of these faces makes every fall longer than it looks.

Related reading

• 10 Alaska Facts: Scale, Landscapes and Life Beyond the Stereotypes
• A slow-moving avalanche in Valais
• Candide Thovex’s One of Those Days 3: A Skier’s View of an Inventive Film
• Skiing a Volcanic Slope
• Angela Kelly’s Frozen Bubbles: Ice Crystals, Reflections and Fragile Forms
• Frozen Bubbles at Mount Washington Observatory
• Soap Bubbles in a Thompson, Manitoba Winter

Sources