What happened
On January 21, 2023, a PZL-Brollsko Model SZD-51-1 Junior glider, registration JA2524, was performing a leisure flight at the Naganoshi glider site in Nagano City, Japan. During the landing phase on Runway 04R, the pilot experienced an unstable approach. After noticing the aircraft was lower than intended, the pilot pulled back on the control stick and partially closed the airbrakes to reach a chosen aiming point. This maneuver caused the aircraft to float higher than expected.
As the aircraft passed the flare marking, the pilot initiated a flare maneuver while the glider was still high. The resulting loss of airspeed caused the aircraft to shake, leading the pilot to fear an impending stall. In an attempt to recover, the pilot pushed the control stick forward immediately before touchdown. This rapid nose-down input caused the aircraft to sink with a downward attitude, resulting in the main wheel and the forward lower section of the fuselage striking the runway violently. The pilot was uninjured, but the aircraft's outer skin sustained damage.
The investigation
The JTSB investigation focused on the sequence of flight maneuvers and the pilot's response to the floating condition. Investigators examined the aircraft's flight manual, which notes that stall recovery involves releasing the stick forward, but also warns that pushing the stick forward at the top of a climb can lead to a rapid sink rate if airspeed is insufficient. The investigation also looked into why the incident was not immediately reported, as the pilot and the Nagano Gliding Association did not initially recognize the event as a reportable serious incident. The matter only came to light when the Civil Aviation Bureau reviewed maintenance records.
Findings
- The pilot's decision to pull the stick back and reduce airbrake extension likely caused an excessive nose-up attitude, leading to the aircraft floating.
- The pilot initiated the flare maneuver before the aircraft had begun to sink naturally, which further reduced airspeed.
- The primary cause of the fuselage contact was the pilot's rapid forward control input in response to perceived vibrations, which caused the aircraft to descend with a nose-down attitude and insufficient airspeed to recover.
- The pilot had selected an aiming point that deviated from the association's recommended center-line marking.