What happened
On May 21, 2018, a SF-28A motor glider departed from the Scharnstein airfield in Upper Austria for a local flight with one passenger on board. During the flight, the pilot shut down the engine to continue in a gliding mode, but failed to move the propeller into the feathered position.
While gliding, the aircraft entered a downdraft characterized by a high rate of descent. In an attempt to return to the Scharnstein airfield, the pilot attempted to restart the engine, but the engine failed to ignite. This necessitated an unplanned forced landing on a meadow approximately 900 meters southwest of the airfield.
During the final approach to the landing site, the right wing of the aircraft struck a low-voltage power pole. The impact caused the aircraft to yaw right, leading to a subsequent impact with the ground on its right side. The aircraft suffered total loss of the airframe, with the right wing separating from the fuselage and the propeller blades breaking off upon impact. There were no injuries to the pilot or the passenger.
The investigation
The Austrian SUB examined the flight sequence, the aircraft's maintenance history, and the pilot's experience. The investigation confirmed that the aircraft was properly maintained and that all required flight documents and certifications were valid. The investigation also reviewed the weather conditions, which were stable with visual meteorological conditions (VMC) and no significant weather-related impediments to the flight itself.
Findings
- The primary cause of the accident was a collision with an obstacle on the ground.
- The pilot lacked sufficient gliding experience specifically on the SF-28A type, which led to errors in estimating the glide ratio.
- The pilot's attempt to restart the engine late in the descent increased cockpit stress levels.
- This heightened stress led to a loss of situational awareness and a distraction that resulted in the wing striking the power pole.
- The aircraft entered a high-sink-rate downdraft area, making the return to the home airfield difficult without engine power.