What happened
While traveling from Atsugi to Subic Bay, specifically Cubi Point NAS in the Philippines, the crew of a four-engine aircraft reported to air traffic control that the third engine had ignited. In response to this emergency, the flight crew decided to divert their path toward Naha Airport in Okinawa.
Shortly after 14:00 local time, the captain provided an update on the aircraft's position, noting a heading of 339° and a steady altitude of 6,500 feet. During this communication, the pilot requested maritime rescue services to be prepared in the event that the plane was forced to ditch in the sea. This transmission proved to be the final contact from the flight.
Following the loss of communication, the aircraft went down in the Pacific Ocean, approximately 290 km southeast of Okinawa Island. Search efforts failed to locate any of the 29 occupants, and no survivors were found. The only evidence recovered from the site was roughly 350 kilograms of floating wreckage.
Findings
Official investigations concluded that the primary factor in the accident was an unexplained fire involving the third engine during the flight.