What happened
On April 23, 2005, a Valentin Kiwi motor glider, registration PH-1247, departed from the Nistelrode glider airfield using the auto-tow method for a local flight. Shortly after takeoff, the aircraft reached an altitude of approximately 50 meters but failed to climb further. Believing the aircraft was suffering from engine failure, the pilot initiated a right-hand turn to return to the airfield.
While flying parallel to the runway at an altitude of about 40 meters, the pilot attempted to turn into a crosswind leg. Fearing a collision with a nearby farm if altitude continued to drop during the turn, the pilot executed a 180-degree left-hand turn toward an adjacent field. During this maneuver, the aircraft lost excessive altitude and struck the ground in a short field approximately three meters before the intended landing site. The impact caused the aircraft to slide through a ditch and undergo a 180-degree ground loop, resulting in heavy damage to the airframe, including a broken tail, displaced engine mount, and damaged propeller blades.
The investigation
The investigation focused on why the aircraft failed to climb and the subsequent loss of altitude during the turn. Investigators discovered that the air brakes were not locked in the retracted position, meaning they had deployed during flight.
Witnesses provided critical testimony, noting that the air brakes were visible and open during the initial climb. One witness reported this via radio to the pilot, but received no response. A second radio warning regarding the open brakes was also ignored. Subsequent examination confirmed that the air brakes remained extended throughout the flight duration.
Findings
- The pilot failed to notice that the air brakes were deployed, leading to the incorrect conclusion that the engine was malfunctioning.
- The pilot performed the pre-flight cockpit check from memory rather than using a checklist, which resulted in the failure to verify that the air brakes were properly locked.
- The deployment of the air brakes during the climb phase was the primary factor preventing the aircraft from maintaining altitude.