Casualties unknown

2003-08-09: Cessna 340A (N340DC) — Bishop, CA

Bishop, CA, US

On August 9, 2003, a Cessna 340A (registration N340DC) was involved in an aviation accident near Bishop, CA. 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 U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 1781061362Data APIEditorial standards

During a nighttime takeoff initial climb, the airplane collided with terrain near the airport after witnesses observed unusual attitude changes and a descent.

Accident Narrative

During a nighttime takeoff initial climb, the airplane collided with terrain near the airport. The departure direction was toward a mountain range with sparse population and few ground reference lights.

Witness Observations

Witnesses reported watching the airplane accelerate on runway 12, rotate, and climb to 200 to 300 feet above ground level. The climb rate decreased and the airplane appeared to initiate a left turn, with the roll continuing to a wings vertical attitude. At this point the airplane descended into the terrain. One witness north of the accident site described the landing lights going from horizontal to vertical followed by a decrease in engine sound just before impact.

Pilot Background

According to the airplane owner, the pilot had never flown the accident airplane before the first leg to the accident location to drop off the owner and another passenger. Examination of the pilot records failed to locate any previous flight time in Cessna 300 or 400 series airplanes. In the last 30 days he had given instruction in a smaller light twin engine airplane.

Aircraft Examination

Post accident examination of the wreckage revealed the landing gear to be 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. The impact site was east of the airport about 0.68 nautical miles.

Environmental Conditions

The moon's disk was 25 degrees above the southeastern horizon and was 89 percent illuminated. The FAA AC61-23C Pilot's Handbook of Aeronautical Knowledge addresses the environmental factors and potential in-flight visual illusions, which could affect pilot performance. The reference material describes Somatogravic Illusion as, "a rapid acceleration during takeoff can create the illusion of being in a nose up attitude. The disoriented pilot will push the airplane into a nose low, or dive attitude. A rapid deceleration by a quick reduction of the throttles can have the opposite effect, with the disoriented pilot pulling the airplane into a nose up, or stall attitude."

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20030812X01317. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.