What happened
On September 11, 2009, a Bell 412EP helicopter, registration JA96GF, was conducting a mountain rescue operation near the Roba-no-moli area of Mt. Okuhotaka-dake in Gifu Prefecture. The aircraft, operated by the Gifu Air Rescue Team, had departed Gifu Air Base earlier that afternoon to assist a person in need of rescue on a mountain trail.
During the mission, the crew attempted to hover near a steep rock wall to facilitate a hoist operation. While maneuvering to avoid nearby rock formations, the main rotor blades made contact with an east-west rock wall. This impact caused the tail boom to fracture and detach from the fuselage. The resulting loss of control led to the aircraft crashing, which triggered a post-impact fire. Of the five people on board, the captain, a mechanic, and a firefighter were killed, while two crew members who had already descended to the rescue site survived.
The investigation
The Japan Transport Safety Board (JTSB) examined the flight path, the mechanical state of the Bell 412EP, and the meteorological conditions at the time of the accident. Investigators analyzed the wreckage, including the severed tail boom and the damaged main rotor blades, to determine the sequence of events leading to the structural failure. The investigation also reviewed the operational management of the Gifu Air Rescue Team, specifically focusing on the decision-making process regarding dispatching the aircraft into complex mountainous terrain and the adequacy of existing rescue guidelines.