What happened
On February 1, 2015, a privately owned Schempp-Hirth Discus b glider, registration JA2531, was conducting a solo familiarization flight at the Yomiuri Kazo gliding field in Saitama Prefecture, Japan. During the approach to runway 31, the pilot was managing an approach speed of approximately 130 km/h to account for reported wind gusts of up to 12 m/s.
As the aircraft descended to an altitude of roughly 15 meters, it experienced a violent shake and a sudden sink. While the pilot initially believed the landing could proceed normally, the aircraft entered an unintended nose-up attitude during the flare maneuver at an altitude of about 5 meters. In an attempt to correct this excessive lift, the pilot reduced the upward pressure on the control column. This action inadvertently caused the glider to lose lift and enter a sudden nose-down descent. Lacking sufficient altitude to recover, the pilot performed a hard landing, causing the canopy to break and the fuselage to sustain significant damage.
The investigation
The investigation examined the meteorological conditions, the pilot's maneuvers, and the aircraft's mechanical state. Investigators noted that the gliding field is prone to topographical air disturbances when northwest winds blow, particularly due to a nearby 9-meter embankment. The investigation also reviewed the pilot's flight controls and the relationship between the approach speed and the wind conditions present at the time of the accident.