WHEN SCOTT MACARTNEY entered the gate at the January 2008 World Cup downhill race in Kitzbühel, Austria, he gave the start referee a rare, brief smile. Positioned in the top 20 after his final practice run, Macartney was celebrating his 30th birthday, a coincidence that felt lucky. As he waited for the countdown, a coach told him, "Today's your day."

In fact, it was almost his last. Entering the final jump at 89 miles per hour, he felt what he later described as a "pop" under one foot: a kick on the takeoff as one ski hit what was likely a raised patch of snow. This imbalance magnified in the air, and Macartney's body began a grim, inexorable rotation. For two seconds—180 airborne feet—he fought unsuccessfully to right himself. When he hit, facing sideways, the impact snapped both skis and fractured his inch-thick helmet, which broke off and ricocheted across the snow. Unconscious, Macartney tumbled gruesomely and slid down the rest of the hill. Finally drifting to a stop past the finish line, he lay still for a moment and then went into a seizure and convulsions.

Watching from the sidelines, Macartney's coach, Chris Brigham, judged the wreck "one of the worst I've seen." Macartney was airlifted to a hospital in Innsbruck, where he was put into a coma. It was unclear at first whether he would live.

Back on the course, news of the disaster propagated quickly. Macartney had had an early gate time—he was only the second skier to descend—and the accident had been broadcast live to the other racers, including his teammate Marco Sullivan, who was in the lodge at the top of the course. On the room's television, the crash replayed twice before the feed was cut, and Sullivan later told me he assumed Macartney had broken his neck. "The thing that freaked everybody out was the convulsions," he said.

At the hospital, Macartney spent 13 hours unconscious while doctors tried to control the swelling in his brain. He was lucid when he woke up, although he had trouble remembering names and his vision was blurred in one eye.

Despite this, Macartney recovered, and soon announced his intention to return to competition—and to Kitzbühel. Over the summer of 2008, he met once with the Ski Team psychologist, Keith Henschen. Otherwise, he didn't discuss the accident in public and seemed to find the idea of dwelling on his feelings unpalatable. Though the science of fear therapy has burgeoned in recent years, Macartney's own plan for recovery remained decidedly old-school: He would keep his mouth shut and get back on the horse.

"In the end, it's about the amount of risk you're willing to take," he said when asked about the wreck. "Either you get used to it or you don't. The sport selects for the people who can." Not long after, he reclaimed his spot on the U.S. Ski Team, and in September 2008 he left for the squad's race camp at Portillo, a Chilean ski resort high in the Andes.