United Air Lines Trip 4

United Air Lines Trip 4 was a Boeing 247D operating on a scheduled flight from Salt Lake City, Utah, to Cheyenne, Wyoming, on October 7, 1935. The aircraft last contacted Cheyenne at 02:16 or 02:17, reporting its position as Silver Crown. Cheyenne called the flight at 02:21, receiving no reply. The weather was virtually clear with ceiling unlimited.

United Air Lines Trip 4

A Boeing 247 similar to the accident aircraft
Accident
Date	October 7, 1935
Summary	Controlled flight into terrain caused by pilot error
Site	Laramie County, near Silver Crown, Wyoming, USA
Aircraft
Aircraft type	Boeing 247D
Operator	United Airlines
Registration	NC13317
Flight origin	Salt Lake City, Utah
Destination	Cheyenne, Wyoming
Passengers	9
Crew	3
Fatalities	12
Survivors	0

The wreckage was located 3 mi (4.8 km) east of Silver Crown. The aircraft struck the ground in a shallow descent just below a small knoll. Marks on the ground made by the propellers, fuselage, and engine showed the aircraft was in a normal flight attitude. Propeller marks and engine damage established the engines were developing normal power and the aircraft was at cruising speed. An untouched knoll 60 ft (18 m) further back on the flight path and 3 ft (0.9 m) higher established that the aircraft was descending.

The pilot was believed to be flying on instruments. The probable cause was determined to be pilot error in failing to monitor altitude or location.