What happened
While en route from San Francisco to Chicago, the crew reported a fire breaking out in the rear section of the Douglas DC-6. The pilots decided to divert to Gallup Airport for an emergency landing. During the approach, the aircraft became difficult to control and touched down while still on fire. Once the plane came to a complete stop, all 25 occupants disembarked rapidly. Local rescue personnel assisted the evacuees before the structure was completely consumed by the blaze.
Findings
The investigation identified that gasoline had entered the cabin heater combustion air intake scoop. This occurred due to an inadvertent overflow from the No 3 alternate tank vent while fuel was being transferred from the No 4 alternate tank. The combustion of this leaked gasoline was determined to be the primary cause of the accident. Contributing factors included the manufacturer and the Civil Aeronautics Administration failing to exercise sufficient caution in analyzing the fuel system design, specifically regarding the location of tank vents for safe drainage. Additionally, there was insufficient attention paid by the manufacturer, regulators, and air carriers to the specific fuel management procedures required for pilots operating this aircraft type.