Amateur-built RV-9A accident near Tribune, Kansas, February 23, 2014

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

According to data recorded by the experimental, amateur-built airplane's multifunction displays, about 10 minutes after the airplane took off for the personal flight, it entered two sequential 360-degree left turns with gravitational accelerations (g) of 2.10 g and 2.80 g, respectively. The airplane then entered its final left turn with an acceleration of 3.20 g, passed through about 180 degrees, and subsequently descended into terrain. Examination of the airplane wreckage revealed no mechanical anomalies that would have precluded normal operation. A review of the private pilot's primary care physician and neurologist records revealed that the pilot had a 10-month history of a rapidly progressive neurological disorder that affected his muscle movements. Three months before the accident, the primary care physician advised the pilot not to drive or fly due to his impaired response time. Four days before the accident, the neurologist noted that the pilot had asymmetric moderate rigidity in his arms and severely slowed movements generally. The postmortem neuropathology analysis identified widespread degenerative disease in multiple areas of the brain. It is likely that the pilot's neurologic disorder impaired his ability to safely operate 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.