What happened
During a nighttime flight conducted under instrument flight rules (IFR), a twin engine aircraft collided with the slope of a mountain in the vicinity of Yakima. At the time of the impact, the aircraft's autopilot system was engaged. The wreckage of the plane was located by search teams one day after the incident occurred.
The accident resulted in the total destruction of the airframe and one fatality, involving the pilot. No other occupants were reported injured.
Findings
Investigations into the crash determined that the aircraft was operating approximately 10 miles away from its planned flight path at the time of the collision. The official conclusion identified the primary cause as controlled flight into terrain.