What happened
On September 23, 2018, a Rolladen-Schneider LS4-B glider, registration LN-GCM, was performing a training flight at Hokksund Airport (ENHS) in Norway. During the landing phase, the student pilot failed to reach the runway, instead touching down on a field approximately 150 meters short of the threshold for runway 28. As the aircraft rolled along the field, it struck bushes and small trees, resulting in significant damage to both wings. The pilot, who was flying solo, escaped without injury.
The investigation
The investigation, conducted by the Norwegian Glider Association (S/NLF) and overseen by the NSIA, examined the flight path, weather conditions, and technical state of the aircraft. The pilot reported experiencing unexpected sink and strong headwinds on final approach, which led to the decision to land short of the runway to avoid obstacles.
Crucially, a witness acting as the ground manager observed the aircraft during its approach and noted that the airbrakes appeared to be extended throughout the entire final approach. Technical inspections of the Rolladen-Schneider LS4-B confirmed that the aircraft's mechanical systems, including the altimeter and airspeed indicator, were in good working order. The investigation also looked into the pilot's training progress and the flight school's adherence to standard procedures.
Findings
Several contributing factors were identified in the sequence of events:
- The extended airbrakes were a primary factor; the deployment of the brakes created a steeper glide angle, which the pilot likely misidentified as unexpected atmospheric sink.
- The pilot failed to maintain standard landing patterns, specifically regarding altitude references and the use of visual markers.
- There was evidence that the flight school had not fully verified the student's proficiency in specific landing maneuvers.
- The pilot's previous experience in powered aircraft may have influenced the instructors' perception of his readiness for solo glider operations.
Safety action
Following the incident, the investigation highlighted the need for improved training regarding abnormal situations during the landing pattern, such as when a pilot realizes the runway is unreachable. The ground manager's testimony emphasized that the airbrakes were likely not properly secured after the pre-landing checklist, a mistake that can lead to them deploying unintentionally during flight.