When Dave Boon first saw the avalanche that swept his car over a guardrail on Interstate 40 in Denver, Colorado, it was only "a puff of powder, 10 yards ahead" of his two-door Honda Accord. After that brief warning, a snowy burst of wind knocked the car out of control. "Not even a second later," Boon said, "a freight train hit us"—what he later learned to be a roaring boxcar blast of tons of mountain snow.

Boon had traveling with his wife, June, and a 13-year-old boy named Gary Martinez on their way to a youth group ski trip. According to Martinez, the three of them had been discussing the possibility of an avalanche before they were struck. "It was before we turned the corner," he said, "and we were talking about avalanches and how there was so much snow and stuff. Then we turned the corner and saw some white powder, and it slammed us into the guardrail."

The wall of snow knocked the car up over the rail and sent it crashing and rolling hundreds of feet down a steep mountain slope. In the middle of the descent, the car struck a tree and was knocked out of the avalanche's grasp. It came to a stop upside down and pointing back uphill.

Fortunately, Boon and his wife were well trained. After clearing an airway and freeing himself from the seatbelt, Boon was able to exit the car along with Martinez, then cut his wife free from her restraints. Despite several bumps, bruises, and scrapes, none of the three required hospitalization.

For Boon, the experience was a reminder that warnings and hints of danger need to be respected. "The signs say, 'Avalanche Area, No Stopping,'" he said. "We've driven by there hundreds of times…. We have skied avalanche chutes, worn (emergency) beepers, always carried an avalanche shovel. We've seen avalanches. But in our wildest dreams, we never imagined getting hit in a car by one."