LAKE LOUISE, Alta. — The mother of a search and rescue technician who went missing when an avalanche apparently swept him off a ledge says she understands why the search is taking so long.

Liz Quinn says the search area in Banff National Park is still under threat from more avalanches and must be secured before ground teams can try to find her son, Sgt. Mark Anthony Salesse.

The Canadian Armed Forces says in a news release that snowfall around the ice-climbing route known as Polar Circus has been “unrelenting” since the accident late Thursday afternoon.

The release says Parks Canada is using dog teams and air support to try to find Salesse, but that the snow and avalanche hazard continues to hamper the search.

Quinn says military officials have told her that searchers will need to trigger more avalanches to make the area safe for ground crews to enter.

She says that means more snow and debris will land on the area where it’s believed her son landed.

“They cannot risk the lives of any other search and rescue personnel and I can’t blame them,” Quinn said on Saturday afternoon from her home in Moncton, N.B.

“Those people — those search and rescue — all have families, they have parents, they have wives. So we are prepared to receive the worst.

“If anyone can survive this Mark can, but the elements are against him.”

Park Canada said in a news release Saturday that it was waiting for the weather to improve before it could begin “explosive control.”

“At this point we believe the chances of survival to be minimal and have therefore moved into a recovery operation,” said Tania Peters, a Parks Canada spokeswoman, in an email.

Salesse, 44, was training at the time of the avalanche with other search and rescue personnel, according to the military.

Quinn said the military told her that her son was climbing up the ice wall when the weather, which was supposed to be good, suddenly worsened. The climbers, who were in two teams of two, turned around and headed back down.

Salesse was in the lead and stopped on a ledge to wait for his partner, Quinn said. But when his partner got to the ledge, Salesse was gone.

“Mark was no longer to be seen. His footprints were in the snow and then they disappeared where there was debris and everything that had gone over the ledge,” Quinn said.

“Mark fell about 800 feet, and more snow and debris from one or more avalanches fell on top of him.”

Parks Canada said Salesse’s partner searched the avalanche debris extensively but wasn’t able to find him.

Salesse, who was born in Bathurst, N.B., is with the 435 Transport and Rescue Squadron based at 17 Wing Winnipeg.

Quinn said her son is an experienced ice climber with 25 years experience. She said he was severely injured in 2011 in a fall during a military ice-climbing exercise near Ouray, Colo., which required almost a year of hospital stays and rehabilitation.

At the time, Salesse was with 5 Wing Goose Bay, N.L. He suffered injuries to his lower back, ribs, leg and pelvis.

Salesse was also stationed for a time at CFB Comox in British Columbia, and has been a member of the Governor General’s Foot Guards in Ottawa. He won a Governor General’s Medal for bravery for service in Croatia.

He isn’t married and doesn’t have any children.

Quinn said her son didn’t think it was fair to have a wife and family and not be there for them. Recently, though, she said he was considering settling down and having a family.

“My only consolation at this time is that Mark was doing what he loved best,” she said.

—by Rob Drinkwater in Edmonton