Amateur-built STEEN SKYBOLT accident near Easton, Minnesota, May 6, 2013

The NTSB's narrative final · quoted from the NTSB record

The pilot performed aerobatic maneuvers for about 5 minutes near a friend's farm and then departed the area. About a minute later, the airplane reappeared and began a left bank that became a spiral descent until ground impact. An examination of the airplane revealed no preimpact anomalies that would have precluded normal operation. The autopsy revealed that the pilot had severe coronary artery stenosis in the proximal left anterior descending coronary artery. According to the pilot's wife, although he had symptoms that may have been related to this disease, he had not received medical attention for them, so the disease was undiagnosed. She added that he had experienced dizziness while previously flying aerobatic maneuvers. In addition, both the pilot's father and grandfather experienced premature sudden cardiac death, which doubled the his risk of having sudden cardiac death. The autopsy was unable to determine whether an acute cardiac event occurred at the time of the accident. However, based on the pilot's recent medical symptoms, severe fixed coronary artery stenosis, and family history of sudden cardiac death and the additional physiologic stress of performing aerobatics, it is likely that the pilot became incapacitated due to an acute cardiac event and lost control of the airplane.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.