What happened
The airplane was on the downwind leg, approaching a point abeam the runway threshold, when it collided with terrain. Prior to the accident, auxiliary lighting had been installed in the glareshield; however, because this did not provide sufficient light, the pilot used two flashlights clipped to the glareshield and two additional handheld flashlights to illuminate the instrument panel.
The aircraft maintained a gradual descent while flying south of the airport and then executed a left turn toward the north on the downwind leg. During this maneuver, the airplane continued to descend until the impact occurred. The pilot and passenger were both thrown forward and to the right by the force of the impact.
The investigation
Investigators examined the cockpit lighting conditions and found that the use of multiple flashlights would have prevented the pilot's vision from achieving dark adaptation, likely interfering with his ability to see outside the aircraft. The pilot's medical history was also reviewed, noting significant past eye surgery, including a corneal transplant, which can cause vision impairment.
Analysis of the pilot's specimens revealed the presence of cocaine and its metabolites (benzoylecgonine and ecgonine methyl ester), as well as temazepam, oxazepam, and acetaminophen.
Structural analysis of the aircraft showed that the lack of shoulder restraints concentrated deceleration forces on the lap belt. This resulted in the separation of the floor where the seat belt was attached. The damage and fractures observed were consistent with a single overload event and indicated substantial forward rotation of the attachment point during separation, which, combined with centrifugal force, caused the pilot to strike the instrument console.