They were analyzing conditions, digging snowpits and doing everything by the book when the avalanche broke loose above Silverton, Ryan Moomey said last week.
Moomey was skiing with Olivia Buchanan on Jan. 6 when Buchanan triggered a slide on a gully called Rabbit Ears at about 11,000 feet. The slide carried Buchanan several hundred feet down the mountain, and she was unresponsive and not breathing by the time Moomey reached her.
Buchanan, 23, a 2010 Durango High School graduate who was studying snow science at Montana State University, was evacuated by rescue crews to Silverton and taken via helicopter to Mercy Regional Medical Center. Staff there could not revive her.
"She was just so smart about everything she did all day," said Moomey. "She took every protocol you're supposed to do."
Avalanche conditions were classified as "moderate" when Moomey and Buchanan went out. Brian Lazar, deputy director of the Colorado Avalanche Information Center, said "moderate" means that natural, slides are not expected.
"But on some of those suspect slopes it's not necessarily likely but it's certainly possible for a person to trigger a large and destructive avalanche," Lazar said.
Moomey and Buchanan climbed most of the way up Kendall Mountain from Silverton, then headed down.
They took turns skiing, stopping and watching each other.
"Within the blink of an eye the snow just let go, and then she went down," Moomey said.
After the slide, he switched his avalanche beacon to receive and skied down a rocky slope nearly shorn of snow. Avalanche forecasters measured the slide as 2 to 4 feet deep and about 150 feet wide; it started on an average 40- degree slope.
It took a couple of minutes, but Moomey found her in a grove of trees, her torso wrapped around a tree trunk and her head slightly buried.
Moomey pulled her off the tree, and tried to get her airway open. She was not breathing, and he called 911.
He continued with CPR for about an hour before four members of San Juan Search and Rescue arrived.
"I felt so alone," Moomey said. "I could see the town, and I could see everybody (mobilizing for the rescue), but I was just up there by myself with her. ... I was so scared for her."
Search and Rescue took Buchanan down the mountain in the growing darkness.
Moomey has been skiing the backcountry for a decade, has attended an avalanche school. Buchanan interned with the Silverton Avalanche School in 2011.
Both were wearing helmets and had beacons, shovels, probes, first-aid kits and extra gear, Moomey said.
Lazar, with the Avalanche Information Center, offered condolences to Buchanan's family and friends. He encouraged backcountry users to avoid slopes that seem at all questionable.
"Have fun recreating on all the other types of terrain available. ... There's plenty of other options available," he said. "This was a fairly committing steep terrain feature with serious consequences should something even small go wrong. And unfortunately that's what happened."
Freelance writer Samantha Wright contributed to this report.