What happened
On August 4, 2018, a training flight involving a Janus C sailplane, registration SE-UUB, experienced a sudden loss of control during a winch launch at Västerås/Johannisberg airport. The flight was being conducted by an instructor and a student, with the student acting as the pilot flying.
While the initial phase of the launch appeared normal, the aircraft suddenly yawed to the left, reaching a bank angle of approximately 45 degrees. The student attempted to use right rudder and aileron inputs to counteract a crosswind, but these corrections were ineffective. The instructor took control of the aircraft and disconnected the winch cable at an altitude of roughly 40 to 50 meters. To regain airspeed, the instructor maintained a nose-down attitude through the turn.
The aircraft subsequently landed on an uneven, rough grass field in a direction opposite to the takeoff runway. During the landing, the left wingtip struck a fence, causing the aircraft to veer 90 degrees. The main wheel hit a plowed field edge, causing the aircraft to bounce and slide sideways before coming to a stop. While the occupants escaped without injury, the Janus C sustained substantial damage, including cracks in the fuselage, a broken stabilizer, and damage to the nose wheel, cowling, and wingtip.
The investigation
The Swedish Accident Investigation Authority (SHK) examined the aircraft's flight controls, which were found to be fully functional and free of movement restrictions. Investigators also reviewed flight data logs, which confirmed the aircraft's position and altitude during the event.
During the investigation, the team observed several winch launches at the club. These observations revealed a pattern where the transition to the climbing profile occurred too early. Furthermore, witness testimony suggested a local club culture where winch starts were frequently performed with an excessively rapid and steep initial climb.
Findings
- The primary cause of the accident was that the initial climb attitude increase was performed too fast, which induced a stall.
- There were indications of operational deficiencies regarding winch launch procedures at the aero club.
- A lack of recent oversight was noted, as the Swedish Transport Agency had not conducted formal operational oversight of the club's activities since late 2014.
Safety action
- The Swedish Transport Agency is recommended to ensure that oversight of sailplane operations is conducted in a manner that meets all current regulatory requirements.