SOMBA K'E/YELLOWKNIFE - Mechanical failure has been ruled out as a possible explanation as to why a Yellowknife-based helicopter crashed on a mountain near Watson Lake, Yukon last month.

None of three occupants, including the pilot, on board the Trinity Helicopters chopper were seriously injured during the incident April 16. The company started operations out of Yellowknife in January, and has seven Bell helicopters in its fleet, according to the company's website.

On the day of the crash, a Trinity Bell 206 Long Ranger from Yellowknife had stopped in Watson Lake on its way to Whitehorse, Yukon. The pilot and two surveyors then took a trip up to a mountain ridge about 5,000 feet above sea level, and as it was trying to land it took an "unanticipated yaw," which caused the helicopter to roll on to its side when it hit the ground.

Mike Tomm, an operations investigator with the Transportation Safety Board of Canada, said the helicopter was recovered a few days later and taken to a maintenance facility in Kamloops, B.C., where it was determined that there were no mechanical problems with the craft.

Tomm called it was just "a low level investigation."

"We just collected basic information on (the crash). We didn't pursue in a big way."

All three occupants were able to walk back down to a resort camp at Watson Lake "no worse for wear," according to Tomm.

"The intent was to land on top of the ridge to do some photography. As the pilot attempted to land, the helicopter took an unanticipated yaw," said Tomm.

He said the cause of the crash is still unknown, but "atmospheric conditions could have contributed to it."

Rob Carroll, president of Trinity Helicopters, said the company is still looking into whether or not the crash was a pilot error.

"We're not sure at this point what this issue was," said Carroll.

"All we know is that there was an incident and there were no injuries."