Accident Overview
A commercial pilot was conducting an instrument approach in a single-engine turboprop airplane after a 3.5-hour cross-country flight under instrument flight rules (IFR). Approximately 1.6 miles from the runway threshold, the airplane began a climb consistent with the published missed approach procedure. However, instead of completing the slight left climbing turn toward the designated holding point, the aircraft continued in an approximate 270° left turn with varying altitude, before entering a descending right turn and impacting terrain. Tree and ground impact signatures indicated a 60° nose-low attitude at impact. No distress calls were received from the accident flight. A postimpact fire consumed most of the cockpit and fuselage.
Flight and Weather Conditions
Weather at the time of the accident was IFR to low IFR, with gusting surface winds, light to heavy snow, mist, cloud ceilings between 700 and 1,400 feet above ground level, and clouds extending through 18,500 feet. There was potential for low-level wind shear and clear air turbulence. The accident area was under AIRMETs for IFR conditions, mountain obscuration, moderate icing below 20,000 feet, and moderate turbulence below 18,000 feet. A winter storm warning had been issued about six hours before the flight departed. The pilot had received a weather briefing approximately 17 hours before the accident, but there was no indication of updated weather information before departure or during the flight.
Investigation Findings
Examination of the airframe and engine revealed no preimpact anomalies that would have precluded normal operation. However, fire damage precluded examination of the avionics system. The airplane was equipped with standby flight instruments. An acquaintance reported that the pilot had experienced an avionics malfunction several months earlier, during which the flight display went blank while flying an instrument approach. On that occasion, the pilot used ForeFlight on an iPad to maneuver and fly the approach again using his own navigation. During the accident flight, the airplane appeared to execute a missed approach, but rather than following the published missed approach procedure, it turned left toward the northeast, similar to the previous incident. Investigators could not determine whether the pilot was attempting to fly the approach using his own navigation or was experiencing spatial disorientation. The restricted visibility and turbulence present at the time were conditions conducive to the development of spatial disorientation, and the airplane's turning flight track and steep descent profile are consistent with its known effects.
Probable Cause
The probable cause of the accident was the pilot's loss of control due to spatial disorientation.