What happened
On May 15, 2024, at approximately 13:45 JST, a privately owned SOCATA TB21, registration JA4022, was performing touch-and-go training at Fukui Airport. The aircraft, operated by a single pilot, was executing a pattern that involved an intentional delay in extending the landing gear as part of the training procedure. During the final approach, the pilot encountered wind conditions that required corrective maneuvers to stabilize the approach angle and airspeed.
As the aircraft neared the runway, the pilot noticed the landing gear warning signal and immediately moved the gear lever to the down position and set the flaps to 40 degrees. However, the aircraft touched down on Runway 18 while the gear was still in the process of extending. Because the gear was not yet downlocked, the weight of the aircraft caused the landing gear to retract into the fuselage upon impact. This resulted in the lower fuselage and the propeller making contact with the runway surface. The pilot was uninjured.
The investigation
The JTSB investigation focused on the sequence of the landing gear extension and the pilot's cockpit procedures. Investigators examined the aircraft's hydraulic system and landing gear mechanism, finding no mechanical defects in the downlock mechanism itself. While the investigation noted that the landing gear warning system failed to function correctly during the post-incident inspection, it was determined that this failure was likely caused by the impact of the belly landing rather than a pre-existing malfunction.
Investigators also reviewed the pilot's operational habits. It was established that the pilot frequently performed solo flights without using a checklist, relying instead on memory. Furthermore, the pilot's practice of intentionally delaying gear extension during training significantly reduced the available time to complete the procedure during the final approach.
Findings
- The pilot's decision to delay the landing gear extension increased the workload during the critical final approach phase.
- The need to perform corrective flight maneuvers for speed and altitude caused the pilot to forget the delayed gear extension task.
- The pilot failed to execute a go-around after realizing the gear was not downlocked, choosing instead to attempt the extension immediately before touchdown.
- The landing gear was not fully extended and downlocked at the moment of touchdown, leading to the gear retracting and the aircraft dragging its fuselage and propeller on the runway.