N8634, a DC-8-63CF, did not have the long service life for which it had been built and purchased. It first entered service on January 9, 1969. The following month, it ran off a wet runway after landing at London's Heathrow Airport but was not severely damaged.
About eight months later, on October 16, 1969, N8634 made its last flight. On 12:50 p.m., local time, it took off from Oakland International Airport, California, on a training flight. Aboard were a check pilot, Capt. Bill Headley; a flight engineer, and three first officers who were to receive recurrent training and annual proficiency checks. The training was to include takeoffs and landings at Stockton Municipal Airport, about sixty miles away. After one landing, Headley told the first officer flying, Jim Grant, that it was a touch-and-go landing and he reset the flaps and elevator trim for takeoff as Grant advanced the throttles to takeoff thrust. As he did, the takeoff warning horn sounded intermittently and the blue ground spoiler warning light was on, indicating that the ground spoilers were extended. Headley checked that the spoiler handle was in the retracted position but the blue light stayed on and the horn continued to sound. He decided to abort the takeoff but they were not able to stop in the remaining distance on the runway. He later told the accident investigators that he did not extend the ground spoilers, or tell Grant to extend them, because he believed that they were extended. They ran off the end of the runway, across a dirt road that was approximately ten inches higher than the surrounding land, and onto soft farm land. Impact with the road and ditches caused the left main and nose landing gears to collapse, and a fire to start. The two fire trucks that responded were delayed reaching the scene by the soft ground. The five crewmembers evacuated the aircraft without injury but the aircraft was destroyed by the fire. The $11 million dollar hull loss was the highest in airline history to that point.
The National Transportation Safety Board's accident investigators determined that the ground spoilers were retracted. Their review of the aircraft's maintenance record revealed that there had been three previous occasions when the ground spoiler warning light came on when the spoilers were retracted. Among their conclusions were:
"The ground spoiler extend indicator light remained on and the takeoff warning horn sounded due to a faulty electrical circuit."
"The captain's decision to abort the takeoff was reasonable under the circumstances involved."