1 fatality

2003-08-08: Cessna 340 (N340DC) — WSP Leasing — Bishop, United States of America

Bishop, United States of AmericaTakeoff (climb)

On August 8, 2003, a Cessna 340 (registration N340DC) operated by WSP Leasing was involved in an aviation accident near Bishop, United States of America during takeoff. One person was killed. Investigators recorded the probable cause as: The pilot's in-flight loss of control due to a Somatogravic illusion and/or spatial disorientation. Factors in the accident were the dark lighting conditions and the pilot's lack of familiarity with the airplane. This summary draws on records from the Bureau of Aircraft Accidents Archives (B3A).

Sourcesthe Bureau of Aircraft Accidents Archives (B3A)Primary reportUpdated 1781200913Data APIEditorial standards

During a nighttime takeoff, an airplane climbed to 200-300 feet then entered a left turn and descended into terrain. Witnesses observed loss of control. The pilot lacked experience in the make/model. Probable cause: somatogravic illusion/spatial disorientation in dark conditions.

Accident Sequence

During a nighttime takeoff initial climb, the airplane collided with terrain near the airport. Witnesses reported that the airplane accelerated on runway 12, rotated, and climbed to an estimated 200 to 300 feet above ground level. The climb rate then decreased, and the airplane appeared to initiate a left turn. The roll continued until the wings reached a vertical attitude, at which point the airplane descended into the terrain.

Witness Observations

One witness located north of the accident site described seeing the landing lights transition from horizontal to vertical, followed by a decrease in engine sound just before impact. The impact site was east of the airport, approximately 0.68 nautical miles from the departure end of the runway.

Pilot Background

According to the airplane owner, the pilot had never flown the accident airplane before the first leg of the flight, which included a stop at the accident location to drop off the owner and another passenger. Examination of the pilot's records revealed no previous flight time in Cessna 300 or 400 series airplanes. In the 30 days preceding the accident, the pilot had given instruction in a smaller light twin-engine airplane.

Wreckage Examination

Post-accident examination of the wreckage showed that the landing gear was in the down position at the time of impact. The retractable landing lights were extended, and the nose gear taxi light was destroyed. Both propellers exhibited symmetrical power signatures. No preimpact mechanical malfunctions or failures were identified.

Environmental Factors

The departure direction was toward a mountain range with sparse population and few ground reference lights. At the time of the accident, the moon's disk was 25 degrees above the southeastern horizon and was 89 percent illuminated. The FAA Advisory Circular AC61-23C Pilot's Handbook of Aeronautical Knowledge discusses environmental factors and potential in-flight visual illusions that can affect pilot performance. The reference material describes the somatogravic illusion as a rapid acceleration during takeoff that can create the illusion of being in a nose-up attitude, causing a disoriented pilot to push the airplane into a nose-low or dive attitude. Conversely, a rapid deceleration can have the opposite effect.

Probable Cause

The official probable cause was the pilot's in-flight loss of control due to a somatogravic illusion and/or spatial disorientation. Factors in the accident were the dark lighting conditions and the pilot's lack of familiarity with the airplane.