Accident Overview
The aircraft departed Blackbushe from Runway 08 in fog with visibility reported as less than 500 metres. As the aircraft reached the upwind end of the runway, it was observed banking to the left before disappearing from view. Thirteen seconds later, it crashed into a factory complex, triggering a major fire. All five occupants—the pilot and four passengers—were fatally injured. A substantial portion of the aircraft structure was consumed by the fire.
Investigation Findings
Engineering examination of the remaining structure found no malfunctions in the engines, propellers, or flight controls that would have affected the flight. However, analysis of the cockpit voice recorder (CVR) revealed a reduction in the revolutions per minute (rpm) of one propeller at rotation, which would have resulted in thrust asymmetry. The pilot lost control due to a combination of a lack of visual reference, confusion about the cause of the power reduction, and possible disorientation. Although the pilot may have recognized the situation seconds before impact, insufficient altitude remained for a safe recovery.
Probable Cause
The official probable cause, as stated in the investigation, is as follows: "While the CVR does not provide any comments by the pilot as to the problems he was experiencing, spectral analysis of the CVR recording indicates that a significant difference in propeller rpm occurred at rotation when the pilot would normally have removed his right hand from the power levers. There was no evidence of a malfunction in either engine or the propeller control systems thus it is probable that migration of a power lever(s) occurred due to insufficient friction being set on the power lever friction control. The friction control had been slackened during recent maintenance and it was possible that it was not adjusted sufficiently by the pilot during his checks prior to takeoff. His simulator training had included engine failures but as far as could be established, the pilot had not encountered or been trained for the situation of power lever(s) migration during takeoff. With his level of experience the pilot should have controlled the resultant asymmetric thrust and in reasonable conditions continued the takeoff to a safe height where analysis of the problem could have been carried out. In the event the takeoff was carried out in extremely low visibility conditions leading to the pilot's total loss of any ground references within seconds of lift off. Having controlled the aircraft initially the lack of visual reference with the ground, possible confusion with attitude instrument bank angle display, physical disorientation brought about by cockpit activity and confusion as to the exact nature of the problem led the pilot to lose control of the aircraft at a low altitude. The unusual attitude developed by the aircraft and the reason for the power asymmetry may have been recognised by the pilot several seconds before impact however there was insufficient height available for him to effect a safe recovery. The transition from visual to instrument flight in the low visibility conditions existing at the time of departure was considered to be a major contributory factor in this accident."