Amateur-built RV-9A N7872 accident near Tribune, Kansas

Probable cause

The pilot’s failure to maintain airplane control while conducting high-g turns, which resulted in impact with terrain. Contributing to the accident was the pilot’s improper decision to initiate the flight with a severe progressive neurological disorder that likely impaired his ability to safely operate the airplane.

NTSB analysis

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.

Text from the NTSB. Open the NTSB docket for CEN14LA148 for the full record.