A cousin of a Colorado man who disappeared over the weekend in the Swiss Alps while "speed flying" told FoxNews.com Tuesday the nearby terrain is “impossible to traverse on foot, making a thorough search difficult to impossible.”

Harrison Fast, a 28-year-old from Boulder, vanished Saturday when bad weather rolled in while he and a group of friends were participating in the hybrid sport, a combination of skiing and paragliding.

Here is where we believe Harrison is.

Posted by Harrison Fast Rescue on Tuesday, March 29, 2016

“Based on one cell phone ping at the beginning of the search, the local authorities [had] focused all of their efforts in this single spot,” Cassie Carothers told FoxNews.com.

“I was able to view the area where they suspect Harrison is located from a helicopter and get a full picture of the situation,” she added, noting that the search area would likely expand.

Swiss authorities called off their search Monday, but the family raised more than $49,000 on a crowdfunding site by Wednesday morning to keep the search going with the help of private helicopters and drones.

“We know the odds are against us, but we aren't giving up hope until we exhaust every option,” Carothers said. “Harrison is an amazing person and deserves at least this.”

Carothers, who is building a team with family and friends to keep up the search, said police are not helping them with the drone searches.

“I don’t really go to that place where bad things live, if you will. I keep joking with the family that he’s in some mountain-side bar, talking to a girl with a dead cell phone, not knowing what we are all going through,” his brother-in-law, John Solis, told Fox 31 on Monday.