What happened
An instrument-rated private pilot departed for a personal flight under instrument meteorological conditions (IMC). Shortly after takeoff, while climbing in instrument conditions, the pilot attempted to increase the climb rate using the vertical speed bug on the electronic Primary Flight Display (PFD). However, due to a system error, the changes made via the bug were not transmitted to the autopilot computer.
Following these attempts, the aircraft's vertical speed began to fluctuate significantly, oscillating between climbing and descending for approximately nine minutes. During this period, the aircraft completed three left-hand orbits at varying altitudes. The pilot reported an autopilot problem to air traffic control and requested a diversion to a nearby airport. Despite the request, the aircraft's course deviated further to the left, and the vertical speed continued to oscillate for another four minutes. The aircraft then entered an uncontrolled descent, impacted terrain, and was destroyed. There were no survivors.
The investigation
Investigators analyzed recorded non-volatile memory (N/V/M) data from the electronic cockpit flight display system. This analysis revealed that the PFD had failed to align during both a power cycle earlier in the day and the power cycle immediately preceding the accident flight. While the aircraft was moving during the first power cycle, it remained stationary during the critical alignment phase of the second cycle; however, the departure occurred 375 seconds after the power cycle start-up, which may have been insufficient for a successful alignment.
Because the PFD had not aligned, bug settings for altitude and vertical speed were suppressed and not transmitted to the autopilot. Examination of the wreckage showed the pitch trim jackscrew was in the full nose-down position. Investigators determined this condition likely resulted from the pilot applying manual pressure on the control wheel while the autopilot was engaged. No other preimpact malfunctions of the flight control systems, engine, or structure were discovered.
Findings
- The PFD failed to align during the power cycle prior to departure.
- The failure of the PFD to align resulted in the suppression of altitude and vertical speed bug settings, preventing the autopilot from responding to pilot inputs.
- Spatial disorientation occurred while the pilot was attempting to maneuver with reference to a degraded PFD during IMC.
- The aircraft was equipped with standby instruments and dual GPS units that could have provided sufficient information to maintain situational awareness.