What happened
On March 20, 2005, at approximately 07:00, a Hawk II ultralight aircraft departed from Ganyuan Airfield in Shulin, Taipei County, bound for Yilan Airfield. The aircraft, manufactured by CGS Aeronautics, was operated by a pilot and one passenger in a tandem configuration. The flight proceeded normally through the initial climb, heading southeast toward the mountainous region.
At approximately 07:30, while flying near the Xia-ayu Mountain ridge in Wulai, the aircraft struck treetops. The impact caused the left wing to break and the engine to stop after the propeller struck a tree. The aircraft came to rest in a forested area at an elevation of approximately 3,500 feet. Both the pilot and the passenger survived the impact without injuries.
The investigation
The Taiwan Transportation Safety Board (TTSB) investigation focused on the regulatory and systemic environment, as the flight was identified as an unauthorized operation. The investigation established that the aircraft lacked a valid inspection certificate and the pilot did not possess a valid pilot certificate. Furthermore, neither the aircraft owner nor the pilot were registered with any authorized ultralight flying clubs.
Technical examinations of the engine, a Rotax 532UL, showed that while there was some instability at 5,500 RPM, the engine was functional and not the cause of the crash. The investigation also found that the aircraft lacked a real-time positioning system, which significantly hindered the initial notification and search and rescue efforts. The investigation revealed that the Ganyuan Airfield was operating without legal permit, and the lack of authorized flying clubs and landing sites in the region contributed to a widespread culture of non-compliance with aviation regulations.
Findings
- The aircraft struck treetops while attempting to navigate through a gap in the forest, likely due to insufficient separation from terrain during a low-altitude maneuver.
- The pilot lacked sufficient knowledge of the aircraft's performance limits, specifically regarding the stall speed with full flaps.
- The flight was conducted in unauthorized airspace, as the aircraft was operating outside of designated ultralight activity zones.
- The lack of a real-time tracking mechanism prevented timely reporting of the accident, complicating rescue operations.
- Regulatory enforcement was limited by a lack of resources, as authorities could only respond to reports or media coverage rather than conducting routine inspections.