WPR21LA166 · Cessna 140

During a night cross-country flight in visual meteorological conditions, the pilot made a precautionary landing due to a failure of the airplane’s engine tachometer. The audio from an airframe-mounted camera captured the pilot’s post-flight inspection comment that the tachometer cable housing appeared to be intact, and subsequent departure on the accident flight. Shortly after takeoff, the pilot deviated left of the runway heading before entering a right turn, away from an on-course heading toward the destination airport. The departure airport was located in a sparsely populated valley with rising terrain on all sides, and the airport’s chart supplement indicated that a 479-ft hill existed about 1.4 nautical miles north of the departure end of the runway. Sound spectrum analysis of the video revealed that the engine rpm decreased slightly, and the video showed an increase in the airplane’s bank angle. There was no indication on the camera of any distress or malfunction. The increased bank angle of the airplane, along with the airplane’s descent and impact with terrain was consistent with an incipient loss of control. Examination of the airframe and engine revealed no evidence of additional mechanical failure or malfunction that would have precluded normal operation. Review of the pilot’s logbook indicated 10.1 hours of night experience and that his most recent night flight before the accident flight was over 90 days before the accident. The lack of cultural lighting in the vicinity of the airport would have provided few visual cues to help the pilot maintain attitude orientation. In addition, the pilot’s decision to fly the airplane without a functioning tachometer may have served as an operational distraction after takeoff. Given the lack of mechanical anomalies, the departure into impoverished lighting conditions, the pilot’s lack of recent night flight experience, and the descending turn into terrain, the circumstances of the accident are consistent with a loss of control shortly after takeoff as a result of the pilot’s spatial disorientation.

Verbatim NTSB analysis and probable cause from the NTSB dataset