Background
United Air Lines Flight 409 originated at New York, New York, on October 5, 1955, with a destination of San Francisco, California. The flight included intermediate stops at Chicago, Illinois; Denver, Colorado; and Salt Lake City, Utah. The leg to Denver was routine except for traffic delays due to weather, and the flight arrived at Denver at 0551 on October 6, one hour and 11 minutes late. Routine crew changes occurred at Chicago and Denver. The crew that operated the final leg consisted of Captain Clinton C. Cooks, Jr., First Officer Ralph D. Salisbury, Jr., and Stewardess Patricia D. Shuttleworth. No discrepancies were reported by the previous crew, and none were found at Denver.
Flight History
While at Denver, the aircraft was refueled to a total of 1,000 gallons of gasoline. Prior to departure, Captain Cooks was briefed by the company's dispatcher on en route weather, based on U.S. Weather Bureau sequence reports and forecasts, as well as the company meteorologist's forecasts and analysis. Following the briefing, the flight was dispatched to Salt Lake City via airways V-4, V-118, V-6, and V-32, to cruise at 10,000 feet in accordance with Visual Flight Rules (VFR). The estimated en route time was two hours and 33 minutes. The only obligatory reporting point was Rock Springs, Wyoming. The flight departed Denver at 0633 with 63 passengers, including two infants. At takeoff, the gross weight was 64,147 pounds, 653 pounds under the allowable 64,800 pounds; an error of 100 pounds in excess of the allowable rear baggage compartment weight was made in loading. Flight 409 reported its departure to the company, which was the last known radio contact. When the flight failed to report at Rock Springs at 0811, repeated attempts to establish radio contact were unsuccessful, and the company declared an emergency.
Accident
A widespread search was coordinated by Air Search and Rescue, including the Wyoming Air National Guard, the Civil Air Patrol, and United Air Lines. At approximately 1140 the same day, the wreckage was sighted near Medicine Bow Peak, 33 miles west of Laramie, Wyoming. The Laramie weather at 0728 included scattered clouds at 5,500 feet, visibility 40 miles, wind west-northwest at 13 knots, and snow showers of unknown intensity over the mountains. The aircraft struck the almost vertical rock cliff of the east slope of Medicine Bow Peak (elevation 12,005 feet) at an elevation of 11,570 feet, 60 feet below the top of that portion of the mountain. Two large smudge marks were observed on the cliff face, containing four evenly spaced scars in a horizontal line from the engines and propellers striking the cliff. The aircraft disintegrated on impact, with wreckage strewn over a wide area; some parts were thrown to the mountaintop, others rested on ledges at various levels, and the remainder fell to the slope below. All 66 occupants were killed.
Investigation
Examination of recovered aircraft sections indicated no evidence of fire, structural failure, or malfunctioning of the aircraft or its components prior to impact. The aircraft was observed flying in and out of clouds at an approximate altitude of 10,000 feet, 10 miles southeast of the accident scene and 21 miles west of the prescribed course. The weather along the prescribed route was good, and the aircraft could have been flown safely at 10,000 feet.
Probable Cause
The Board determined that the probable cause of the accident was the pilot's deviation from the planned route for reasons unknown.