What happened
The flight originated from Washington D.C., making several stops including Cleveland, Chicago, and Fargo before continuing toward Seattle. During the segment following a stop in Chicago, the aircraft experienced rough operation of the left engine, prompting a return to the airport where a spare magneto was installed. After further stops in Minneapolis, Billings, and Spokane, the flight proceeded under an IFR flight plan toward Seattle.
During the final leg of the journey, the pilot reported an engine failure while communicating with Seattle Approach Control. Subsequent transmissions indicated that the aircraft was experiencing icing and losing altitude. The pilot's signals became increasingly weak and difficult for controllers to monitor. The final communication from N 65743 occurred at 0222, reporting an altitude of 4,800 feet. Following this transmission, search and rescue operations were initiated.
The accident resulted in 7 fatalities and the rescue of 18 individuals. The Douglas DC-6 was destroyed during the impact.
Findings
Investigations concluded that the crash was caused by the progressive failure of both engines due to inadequate maintenance. While the crew had noted engine irregularities earlier in the flight, these issues were not corrected. Evidence indicated that both engines suffered from detonation and preignition, which ultimately led to master rod bearing failures. Additionally, it was determined that spark plugs in both engines had been used beyond their recommended service intervals.