What happened
During a local flight intended to fly over the Glenbrook area, a two-seat aircraft experienced a sudden and dangerous loss of altitude. Witnesses observing the flight from the ground noted the aircraft flying at a relatively low altitude and performing several circles. During these maneuvers, observers reported an audible change in the engine's performance, noting that the sound fluctuated as if the engine had been throttled back or had momentarily ceased running before increasing in volume again.
As the aircraft transitioned from a southerly heading toward the northeast, it entered a sudden, steep dive while simultaneously turning or twisting to the left. Although the aircraft appeared to regain level flight at a low altitude after a few turns, it almost immediately struck a tree. The impact caused the aircraft to cartwheel into the ground, resulting in one fatality (the pilot) and one serious injury (the passenger).
The investigation
Investigators examined the sequence of events leading up to the impact, focusing on the aircraft's flight path and the audible changes reported by witnesses. The investigation established that the aircraft was operating in a pattern of circling the Glenbrook area prior to the accident. The inquiry focused on the period when the engine sound fluctuated and the subsequent loss of control that led to the steep dive and the collision with the tree.