During a dark night cross-country flight, the instrument-rated pilot was approaching the intended airport for landing when the Piper PA32R-300 collided with the blades of a wind turbine tower near Highmore, S.D., killing all four aboard.
The weather had started to deteriorate and precipitation echoes were observed on radar. Witnesses in the area described low clouds, windy conditions, and precipitation. In addition, weather briefing records and statements made to a witness indicate that the pilot was aware of the current and forecast weather conditions for the route of flight.
Investigators were unable to determine why the airplane was operating at a low altitude, however, the pilot was likely attempting to remain clear of the clouds even though both the pilot and the airplane were capable of flying in instrument meteorological conditions.
The investigation revealed that the wind turbine farm was not marked on either sectional chart covering the accident location, however, the pilot was familiar with the area and with the wind turbine farm.
Investigators were not able to determine what the pilot was using for navigation just before the accident. The light on the wind turbine tower that was struck was not operational at the time of the accident, and the outage was not documented in a notice to airmen.
The wind turbine that was struck was the fifth tower in a string of towers oriented east to west, then the string continued south and southwest with an additional 13 towers. If the pilot observed the lights from the surrounding wind turbines, it is possible that he perceived a break in the light string between the wind turbines as an obstacle-free zone.
The NTSB determined the probable cause as the pilot’s decision to continue the flight into known deteriorating weather conditions at a low altitude and his subsequent failure to remain clear of an unlit wind turbine. Contributing to the accident was the inoperative obstruction light on the wind turbine, which prevented the pilot from visually identifying the wind turbine.
NTSB Identification: CEN14FA224
This April 2014 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.