[1] Some days after the crash, it was learned that the pilot, Reed Pigman, who also happened to be the president of American Flyers, was under care for arteriosclerosis.

[9] An autopsy of Pigman determined his cause of death to either be multiple injuries or coronary artery sclerosis.

[10] It was also determined that Reed Pigman had falsified his application for a first-class medical certificate.

He had not disclosed that he was diabetic or that he had a history of heart issues dating back almost two decades; either of these would have been disqualifying factors for the certificate.

The CAB determined that the probable cause for the accident was: [T]he incapacitation, due to a coronary insufficiency, of the pilot-in-command at a critical point during visual, circling approach being conducted under instrument flight conditions.