1982-02-16: Piper PA-31 Cheyenne (N2517X) — GNC Energy Corporation — Lebanon-Springfield, United States of America

8 fatalitiesLebanon-Springfield, United States of AmericaLanding (descent or approach)

An aircraft crashed while attempting a visual approach in low visibility conditions, resulting from an incorrect altimeter setting and failure to maintain altitude.

What happened

While operating under visual flight rules, the pilot was cleared to maintain an altitude of 3,000 feet MSL until passing the airport. Approximately 15 miles from the destination, the pilot reported seeing ground lights. As the aircraft approached within roughly 6 miles of the airfield, the pilot expressed intent to cancel the existing flight instructions. During this period, witnesses near the site reported encountering dense, patchy fog with visibility restricted to approximately 200 feet.

Observers on the ground noted the aircraft flying at a very low altitude and performing unusual maneuvers. The aircraft struck the terrain in a left-wing-low attitude while positioned near an approximate downwind-to-base leg turn. While the airport operator could see stars, the heavy fog significantly obscured the area near the impact site.

Findings

The investigation identified several contributing factors to the crash. The aircraft was operating during dark night conditions in heavy fog. A critical error involved the altimeter setting; while the airport operator had provided a setting of 29.77, the pilot's altimeter was set between 30.29 and 30.30. This discrepancy, combined with the pilot's failure to maintain the required altitude and the decision to attempt an approach despite visibility being well below the 1-mile requirement for the VOR/DME approach, led to the in-flight collision with terrain.

Probable cause

The accident was caused by the pilot's failure to maintain proper altitude and use the correct altimeter setting during an approach in low-visibility fog.