What happened
A private pilot was operating a twin-engine turbojet on an instrument flight rules flight plan when air traffic control amended the existing routing. This change required the pilot to manually update the aircraft's GPS. Shortly after, the pilot reported difficulties with the navigation unit and requested a direct route to the destination. During a descent from 22,000 feet to 6,000 feet, the cockpit voice recorder captured the sound of the autopilot disconnecting. The pilot subsequently reported steering difficulties while flying in clouds and descended below the assigned minimum vectoring altitude of 4,100 feet.
Although the pilot eventually regained autopilot functionality and was able to climb back to the assigned altitude, the pilot continued to struggle with the GPS and requested further direct routing. The pilot eventually reported an inability to maintain level flight or keep the aircraft straight. After declaring an emergency and expressing difficulty identifying the runway, all radio communication with the controller ceased. Witnesses observed the aircraft perform a 360-degree roll to the left, enter a steep bank, roll inverted, and enter a vertical nose-down dive. The aircraft struck the lawn of a private residence, resulting in a post-crash fire.
Findings
Investigations into the accident highlighted several critical factors regarding the pilot's operation of the aircraft. While the aircraft had been modified for single-pilot use, there was no evidence that the pilot had completed the required annual training for the single-pilot exemption. Furthermore, the pilot's proficiency with the installed GPS was noted as a significant issue; acquaintances indicated the pilot frequently struggled with the unit's interface and became confused when flight plans were amended.
Evidence suggested the pilot relied heavily on the autopilot and failed to properly trim the aircraft before engagement, causing the autopilot to work against the aircraft's trim state. While the autopilot system showed no mechanical deficiencies prior to the impact, the pilot's history of difficulty manually flying the aircraft, combined with the confusion caused by the GPS updates, likely led to the loss of control. It is believed the aircraft entered an aerodynamic stall during its final descent, leading to the fatal impact.