What happened
On July 16, 2022, a Solaseed Air Inc. Boeing 737-800, registration JA807X, was operating a scheduled flight from Naha Airport to New Ishigaki Airport. During the cruise phase at approximately FL260, the aircraft encountered sudden and intense turbulence.
Prior to the event, the flight crew had noted potential turbulence due to clouds near Miyako Island but had decided to maintain the current altitude after visually confirming no immediate threats. As the aircraft began a climb to FL280 to increase separation from clouds seen below, it passed directly over rapidly developing convective activity. At 08:36:41 JST, the aircraft experienced a sudden downward force, with Flight Data Recorder (FDR) records showing a vertical acceleration of +2.053G.
During this moment of instability, the cabin crew were performing in-flight service. The sudden movement caused a cabin crew member to fall while holding service trays, resulting in a fracture of the fifth metatarsal bone in the left foot. All 129 passengers remained seated and uninjured.
The investigation
The Japan Transport Safety Board (JTSB) examined flight data, meteorological records, and crew statements. Investigators analyzed the development of the convective clouds, noting that the cloud tops had risen from 5 km to 9 km in just five minutes—a vertical growth rate of approximately 2,600 feet per minute. The investigation also reviewed the pilot's decision-making regarding vertical versus horizontal avoidance and the cabin crew's service procedures at the time of the impact.