What happened
On July 28, 2011, a Beechcraft A36, registered JA4215, departed from Obihiro Airport for a scheduled flight training session. The aircraft was operated by the Obihiro Branch School of the Civil Aviation College. During the flight, the crew was practicing basic instrument flight (BIF) procedures within a designated training area.
At approximately 09:22 JST, the aircraft struck the slope of Mt. Tsurugi in Memuro-cho, Hokkaido. The impact destroyed the airplane and triggered a post-crash fire. Of the four people on board—consisting of an instructor acting as captain, two students, and an additional instructor—three fatalities were recorded. The fourth occupant, a student, sustained serious injuries.
The investigation
The Japan Transport Safety Board (JTSB) examined the flight path, meteorological conditions, and the organizational safety culture of the flight school. Investigators analyzed the aircraft's trajectory, which indicated the plane entered or flew very close to cloud cover covering the mountainous terrain. The investigation also reviewed the training procedures used during the instrument flight practice and the effectiveness of the college's safety management system. Furthermore, the board looked into the communication and monitoring roles of the instructors on board during the period when the student was flying under a hood.
Findings
- The accident was primarily caused by the aircraft flying into or near clouds that obscured the mountain terrain, leading to a loss of ground references.
- While the student was performing hooded instrument training, the instructor directed the flight into a mountainous area where visibility was compromised.
- Although the instructor attempted to take control to evade the terrain, the aircraft was unable to deviate sufficiently from its course to avoid the slope.
- There were indications of a gap in safety awareness between the college's management and its field instructors, suggesting that the organization's safety culture may have allowed for unsafe operational behaviors.