What happened
On June 14, 2014, at Kinugawa Gliding Field in Tochigi Prefecture, a privately owned SCHEIBE SF25C FALKE, registration JA25CH, was engaged in glider towing operations. The aircraft, operated by a university glider club, had just completed a high-altitude tow of a PZL-BIELSKO SZD-55-1 (JA2555) to test radio equipment.
As the pilot of JA25CH descended toward runway 34 to prepare for the next scheduled tow, a separate winch-launch operation was initiated on runway 16 for an ALEXANDER SCHLIECHER ASK21 (JA2721). During this simultaneous operation, the towline and parachute from the winch-launched glider were released and began descending. While approaching the runway at an altitude of approximately 10 meters, the SCHEIBE SF25C FALKE struck the falling towline. The impact caused the left horizontal stabilizer to break, resulting in substantial damage to the aircraft's propeller, windshield, and landing gear.
The investigation
The JTSB investigation focused on the breakdown in communication and operational coordination between the aircraft pilot and the launch controller. Investigators established that the VHF radio transceiver at the airfield's communication station was defective, preventing the launch controller from transmitting warnings to the approaching pilot. Furthermore, the investigation examined the lack of coordination regarding the simultaneous use of the same runway for both aircraft towing and winch towing.
Findings
- The pilot of JA25CH mistakenly believed the third glider in the sequence was being prepared for an aircraft tow, leading to an accelerated approach to the runway.
- A lack of effective communication occurred because the pilot could not hear the launch controller due to the defective VHF transmitter.
- The airfield's operational rules did not prohibit or adequately manage the simultaneous use of the same runway for aircraft towing and winch towing.
- The preflight briefing between the pilot and the launch controller failed to address the timing of the winch-launch or establish alternative communication methods in the event of radio failure.