On September 21, 1978, the National Transportation Safety Board adopted the accident report and probable cause of the accident. On April 25, 1983, the Bethlehem Steel Corporation submitted a petition for reconsideration of probable cause of the probable cause that was adopted in the original report. As a result of Bethlehem Steel Corporation's petition, the accident report and the probable cause have been revised.
The Safety Board determines that the probable cause of the accident was a locomotive unit axle failure that originated from an overheated traction motor suspension bearing on the second unit of the two-unit locomotive consist. Contributing to the cause of the accident was the lack of an onboard system for detecting a bearing failure independent of crewmembers' inspection.