NATS C-47 registered NC38942 departed Oakland Municipal Airport at 18:42 for a flight to Newark via Cheyenne. Oakland Airway Traffic Control Center authorized instrument flight via Airway Green 3 at an altitude of 11,000 feet to Salt Lake City and 13,000 feet to Cheyenne. At 21:54 Salt Lake ATC instructed the crew to cruise to Cheyenne Airport at 15,000 feet. At that time the weather at Cheyenne was being reported as: ceiling 100 feet, visibility 1/4 mile. By 22:30 the weather at Cheyenne had worsened to a reported zero ceiling and zero visibility. Prior to reaching Laramie the aircraft was cleared from 15,000 feet to 14,000 feet and at 00:05 the flight reported over Laramie. Weather at Laramie was reported ceiling indefinite, 400 feet overcast; visibility 20 miles; light rain. The captain decided to divert to Laramie and he was cleared for an instrument approach. At 00:40 the crew reported outbound on the northwest approach leg preparing for the final instrument approach. By that time visibility had dropped to 2 miles in light snow. Five minutes later the plane passed over the airport at a low altitude. A couple of minutes later the airplane’s left wing tip struck the ground while the aircraft was in a left bank of at least 70 degrees, and while dragging along the ground for a distance of approximately 75 feet, the aircraft crashed and disintegrated. PROBABLE CAUSE: “The action of the pilot in maneuvering the aircraft at a dangerously low altitude under extremely adverse weather conditions in an attempt to land. A contributing factor was the negligence of the pilot in planning a flight into an area in which adverse weather conditions were forecast without making adequate provisions for a suitable alternate airport.”