What happened
A company operating under a VFR only 135 certificate performs daily flights to transport workers to a mine. Prior to this flight, no weather information was obtained from the FAA or NWS; instead, the pilot checked the weather by looking outside and calling the mine.
The aircraft was part of a group of three that departed on an outbound morning trip. Pilots of the other two aircraft reported encountering snow showers, mountain obscuration, and ceilings while en route, which prompted them to turn back and fly south along the mountains to find a clear area for crossing.
On the accident aircraft, four passengers reported encountering snow showers and lowering clouds. The pilot subsequently turned around and flew south for a period of time before heading toward a saddle in a mountain range. As the aircraft entered the saddle, the clouds lowered further, resulting in a loss of outside visibility. The pilot attempted to climb, but as trees began appearing past the side windows, he leveled the wings and pulled the power off. The aircraft then collided with trees and a snow-covered mountainside.