Loss of Control in Flight · NTSB CEN14LA148
VANS RV-9A — Tribune, KS
| Date | February 23, 2014 |
| Location | Tribune, KS |
| Aircraft | VANS RV-9A (amateur-built) |
| Purpose of flight | Personal |
| Conditions | Day · Visual Meteorological Cond |
| Phase / occurrence | Uncontrolled descent Collision with terr/obj (non-CFIT) |
| Pilot age | 63 |
| Pilot total time | 835 hrs · Building experience |
| Time in type | Unknown |
| Fatalities | 1 |
Probable cause
NTSB findings
- Personnel issues-Task performance-Use of equip/info-Aircraft control-Pilot - C
- Aircraft-Aircraft oper/perf/capability-Performance/control parameters-(general)-Not attained/maintained - C
- Personnel issues-Action/decision-Info processing/decision-Decision making/judgment-Pilot - F
- Personnel issues-Physical-Impairment/incapacitation-Neurological-Pilot - F
What happened
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.