Incident Details
The pilot of the airplane called a friend on a cellular telephone as he approached the friend's residence, indicating he was about to pass by. This was a routine call to notify the friend to leave for the airport. During the call, the friend observed the airplane drop rapidly about 1,000 feet while flying toward his house. The airplane was maneuvering very low in a nose-high configuration with full power, flying fast through a slight valley approximately 75 feet above ground level. The friend noted winds from the east, providing a tailwind, estimated at about 40 miles per hour.
Witness Observations
The friend heard the telephone drop, followed by a few inaudible comments from the pilot. The airplane then made a rapid ascent as it neared power lines, climbing in a near-vertical nose-high maneuver to about 1,000 feet above ground level. Subsequently, it performed a 90-degree pivot about the longitudinal axis and continued into a barrel roll, disappearing behind the tree line.
Wreckage and Impact Analysis
Ground scar analysis, impact signatures, and wreckage fragmentation patterns disclosed that the airplane impacted terrain in a near-level attitude with high forward velocity. The impact geometry, combined with witness statements of the airplane rolling immediately after a near-vertical climb, is consistent with the pilot recovering from an accelerated stall and subsequent roll just prior to impact. No evidence of a pre-mishap mechanical malfunction or failure was observed during examination of the engine or airframe.
Weather Conditions
A pilot report in the immediate vicinity and prior to the accident reported continuous light to occasional moderate turbulence between 2,000 and 5,000 feet mean sea level. GOES-11 satellite imagery surrounding the period depicted orographic clouds over and downwind of higher terrain. Five minutes after the accident, a band of tubular or "arcus" clouds, similar in appearance to roll clouds, moved over the accident site. These clouds were short duration and moved southeastward, becoming less distinct about 15 minutes later. Additionally, Vandenburg Air Force Base soundings around the accident time indicated a strong low-level temperature inversion with northerly winds favorable for mountain wave activity formation downstream from high terrain.
Investigation Findings
Based on analysis of the terrain, wind flow pattern, and potential arcus clouds over the area, it is likely the accident aircraft encountered moderate or greater turbulence and downdrafts during the flyby of the residence.