2 U.S. Climbers Missing In China

Considered one of the top female high-altitude mountain climbers in the world, Christine Boskoff has tackled the most summits of any woman alive — including Mount Everest.

Her partner, Charlie Fowler, is among the best-known mountaineers in the United States.

Both set out for Southwest China in October. They were last heard from on Nov. 9th — five weeks ago. And now colleagues from the couple's home base in Telluride, Colo., fear they may never find them. CBS News correspondent Michelle Miller reports.

"It's a needle in a haystack," says Arlene Burns of the Fowler-Bosskoff Search Effort. "We're just basically not even sure which area to go to. The terrain is really challenging. One of the things that all of us worry about is avalanches, and this area is avalanche prone."

They set out well equipped for the harshest conditions found on high-altitude climbs. They had a high-wind capable tent, and a supply of freeze-dried food.

"Every climber knows what they're getting into. They know the risks," says climber Alan Ando.

Ando is a mountaineer who has scaled some of America's highest peaks — including Mount Hood. He's been following the fate of the climbers missing in China.

"Three weeks without water, without food, without shelter, it's a low probability that people will survive," he said.

Since Edmund Hillary and Tenzing Norgay scaled the world's tallest peak half a century ago, mountaineering has pushed the genre of extreme sport.

The ultimate challenge: Mount Everest. Thousands have attempted it. Many of them failed. Fifteen percent of them die trying.

"Remember, world class climbers are attempting things no one else has done. They're on the edge. They're challenging themselves," says Ando.

But in a sport so unpredictable, where weather, terrain and altitude shape every step, skill alone may not be enough.