What happened
On August 22, 2016, a GROB G109 motor glider, registration SE-UDM, was conducting a training flight at Karlskoga Airport. The pilot, an experienced instructor, intended to familiarize himself with operating the aircraft from the right-hand seat. Because the aircraft's airbrake lever is positioned on the opposite side depending on which seat is occupied, the pilot sought to practice this reversed control layout. An instructor sat in the left seat acting as a safety pilot.
The flight proceeded normally until the short final approach. While flying at 12/h, the aircraft experienced an abnormal rate of descent, falling below the intended glideslope. In an attempt to correct the altitude, the pilot adjusted the pitch and managed the airbrakes, but these actions resulted in a loss of lift. The aircraft subsequently struck the ground approximately 50 meters before the grass runway threshold and 250 meters short of the intended touchdown point. The impact was severe enough to cause the left landing gear to detach from the fuselage.
The investigation
The Swedish Accident Investigation Authority (SHK) examined the aircraft and interviewed both the pilot and the safety pilot. The investigation focused on the sequence of control inputs during the final moments of the flight. While the safety pilot noted turbulent conditions and a strong downdraft near the forest edge, he confirmed that the approach speed was correct and did not observe an obvious confusion of controls by the pilot.
Physical evidence at the crash site, including propeller marks in the ground, indicated that the engine was producing power at impact and that the aircraft arrived with a low nose attitude. The investigation also noted that the structural failure of the landing gear caused the seatbelts to tighten with extreme force due to their shared attachment to the same airframe component.
Findings
- The pilot was performing a familiarization flight to learn the reversed control layout of the GROB G109 when seated in the right seat.
- Unlike most gliders where controls are symmetrical, this model features an airbrake lever on the left side of the left seat and the right side of the right seat.
- The pilot's inexperience maneuvering the aircraft from the right seat likely caused an unintentional confusion of the flight controls.
- The sudden loss of altitude and subsequent hard touchdown were the results of improper management of the airbrakes and pitch during the final approach.