christopher carlson, who was wearing a helmet cam, came very close to documenting his own death. it's an avalanche. he is buried about five feet under the snow, unable to move. [ yelling ] >> carlson is hoping the skiers he was with find him before he suffocates. and they do. he's a very lucky man. on the average in the u.s., 28 people die each year from avalanches, often with hundreds of tons of snow plummeting down the mountain. i ski at colorado's copper mountain with one of the top avalanche experts in the united states. >> how are the conditions? >> good for skiing. >> reporter: ethan green is the director of the colorado avalanche information center. his state agency's responsibility in part to forecast the probability of avalanches. >> this is mayflower gulch. >> reporter: he takes me away from the resort and into the back country where most avalanches occur to learn about