What happened
A mission involving a calibration flight departed from Kanoya AFB at 13:15 local time. The aircraft was carrying a total of six crew members. Following the completion of a counter-clockwise maneuver, the flight crew began their descent toward Runway 08R at Kanoya AFB.
During the approach, environmental conditions were characterized by low cloud cover and limited visibility. While flying at an altitude of approximately 3,000 feet, the aircraft penetrated the cloud layer, triggering a Ground Proximity Warning System (GPWS) alert. The crew deactivated this warning approximately two seconds after it sounded and proceeded with the descent. Roughly ten seconds following the deactivation of the alarm, the aircraft type struck trees and crashed on the slope of Mt Takakuma, which stands at an elevation of 1,182 meters. The crash site, located about 10 km north of the airbase, was discovered the following day. There were six fatalities and no survivors.
Findings
The investigation determined that the accident was a result of controlled flight into terrain. Contributing elements included the crew's decision to maintain the approach despite poor visibility and a lack of visual reference to the surrounding environment. Furthermore, the crew's actions in silencing the GPWS alarm and their failure to perform necessary corrective maneuvers were identified as critical factors in the impact.