What happened
On March 26, 2022, a Boeing 767-300, registered JA603J, was operating a scheduled flight from Tokyo International Airport to Oita Airport. The aircraft was carrying 62 passengers and seven crew members. During the cruise phase at approximately 28,000 feet over Nakatsugawa City, the aircraft encountered sudden, severe vertical turbulence.
At the time of the event, the flight crew had recently turned off the seatbelt sign after determining that in-flight services could proceed. Six flight attendants were actively moving through the cabin with service carts. As the aircraft hit a pocket of turbulence, a flight attendant working in the aft galley was caught mid-motion while stowing beverages. The sudden vertical acceleration caused her body to be lifted into the air; she subsequently lost her balance and struck the floor with significant force. While the crew initially reported no injuries, the flight attendant later developed a sacral fracture.
The investigation
The JTSB investigation analyzed digital flight data recorder (DFDR) records, meteorological charts, and crew statements. The data revealed a rapid fluctuation in vertical acceleration, shifting from 1.26G to -0/02G and back to 1.28G within a two-second window. This sudden drop in lift caused the aircraft to momentarily sink, creating the upward jolt that lifted the crew member.
Investigators also examined the weather conditions, noting that while the onboard radar showed no significant echoes, the aircraft had entered an area of atmospheric disturbance. The investigation specifically looked at the flight attendants' ability to secure themselves, noting that the layout of the aft galley made it difficult to quickly grab stable handholds compared to the center of the cabin, where seats were readily available.
Findings
- The primary cause of the injury was the encounter with unpredictable turbulence that could not be detected by the onboard weather radar.
- The rapid change in vertical G-forces caused the flight attendant to be physically lifted from the floor.
- The flight attendant was unable to adopt a protective posture because the turbulence occurred too suddenly and her position in the galley prevented immediate access to stable structures like seatbacks.
- The aircraft's sudden descent and subsequent rise caused the crew member to strike the cabin floor with high impact.