Don't Be Darwin's Fool

Avalanche-safety wisdom to help you survive with the fittest

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The odds might seem tempting: if you get totally buried in an avalanche, your chance of dying is merely 28 percent. Not bad. You figure you'll buy some safety in the form of an avalanche beacon and be on your way. Well, first consider one other cheery stat: Nobody who's been buried under more than seven feet of snow in a North American slide has ever been rescued—transceiver or no. The weight crushes the victim's chest, preventing even the slimmest possibility of drawing another breath. "The compression is unreal," says Jill Fredston, coauthor of the authoritative Snow Sense: A Guide To Evaluating Snow Avalanche Hazard (Alaska Mountain Safety Center, 1999). "It's like those pig-piles when you were a kid."

Indeed, crucial as safety equipment is for mountaineers and backcountry skiers and boarders (see "Stayin' Alive," below), don't assume that a beacon will save your bacon. Simply put, when you go off-piste, you assume risk. "You can learn to recognize avalanche terrain and then just choose to avoid it," says Karl Birkeland, director of the Gallatin National Forest Avalanche Center in Bozeman, Montana. "But that's not the reality. Most of us want to ski that terrain."

Boost your odds by learning how to determine snow stability and pick sensible routes. To start, study the following bare-bones lesson plan, drawn up compliments of Fredston and Birkeland. To master these skills, take an avalanche safety course (see "Get Schooled"), read Fredston's book, study snowpack on flatter terrain, play hide-and-seek with your transceiver, practice rescues, and then, when conditions allow...get out and enjoy the pow. 

FINDING YOUR WAY

Slope Angle Though avalanches can occur on any slope with an angle of 25 degrees or more, slide activity is greatest at 35 to 40 degrees. Measure the steepest section with an inclinometer.

Slope Size Fredston reports that about half of all accidents occur on slopes less than 300 feet long. Avoid terrain traps like gullies, where a piddling
20-foot wall could bury you.

Slope Aspect Leeward slopes collect deposits of dense, windblown snow; shady slopes preserve weak layers. Thus, shady leeward slopes often have weak layers beneath cakes of windblown snow—a perfect recipe for a slab avalanche.

Elevation The higher you go, the colder it is, and the more likely that weak layers persist underneath a thickening slab of snow.

Slope Anchors Exposed rocks and trees tend to hold snow in place, while buried obstacles make good trigger points. But if those exposed trees are widely spaced, beware. "If you're enjoying the tree-skiing, it can slide," says Birkeland. "And when it does, you're in a giant bread slicer."

Partner Up Always travel with a partner, but keep your distance: Traverse or ski iffy slopes one at a time. If one of you gets buried, the other can do the digging.


DETERMINING SNOW STABILITY

Call Local avalanche centers have snowpack and weather information. Check in early and often. Evaluating snow stability is a seasonlong endeavor.

Dig A snow pit will tell you two things: where there's a weak layer, and how unstable it's making the slope. Dig down at least six feet. Depth hoar looks like granules of sugar: It's multifaceted, it glitters, it doesn't make good snowballs. It can kill you. Once you've found the weak layer, perform the rutschblock test (taught in any avalanche school) to determine the slab's shear strength.

Look "If you see slide activity on similar aspects," Birkeland says, "you know the snow is unstable. You don't even have to dig a pit."

Listen A hollow sound underneath your weight means there's a strong layer over a weak layer. This is bad. If you hear a whoomph, the strong layer has just collapsed the weak layer. This is worse. No noise is good noise.

Stomp Extend one leg and smack the snow with your ski tip. If cracks shoot out, the top layer is cohesive and could fracture—two essential components of a slab avalanche.

Repeat Even if everything is telling you to ski that slope, you might have missed something. "It's very rare for a mystery slide to kill someone," Fredston says. "There are usually plenty of clues. It's taking only one piece of information from one particular area that kills people." 

 

STAYIN' ALIVE
A truly essential packing list

Sam Davis has logged thousands of days in avalanche territory as a patroller for Utah's Snowbird ski resort. Aside from the bare minimum of a probe, shovel, snow saw, and transceiver (pictured), here's what you should own for backcountry travel:

  • Snow study kit (inclinometer, snow-crystal card, brush, magnifying glass, thermometers)
  • Forty meters of 8.5-millimeter climbing rope for emergency rappelling, cutting cornices, and belaying while digging a pit
  • Surveyor's tape to flag the perimeter of a debris pile
  • First-aid kit including a small cardboard splint
  • A river rafter's whistle
  • Bivy sack and half an Ensolite pad to warm a victim
  • Water and energy gel
  • Waterproof matches and firestarter

To bone up on avalanche conditions, check out the following Web sites:

U.S. Forest Service National Avalanche Center

Cyberspace Snow and Avalanche Center

Canadian Avalanche Association

Alaska Avalanche School
Anchorage, Alaska 907-345-3566

American Avalanche Institute
Wilson, Wyoming 307-733-3315

Canadian Avalanche Association Training School
Revelstoke, B.C. 250-837-2435

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