On 15 February 2022, a Japan Air Commuter ATR 42-500 operating a scheduled domestic passenger flight experienced a turbulence event during cruise which resulted in a serious passenger injury.
The flight, operating under a Japan Airlines flight number, encountered a sudden, significant vertical disturbance at approximately 9,000 ft. While the aircraft remained structurally unaffected, one passenger sustained a spinal injury.
Following departure, the crew anticipated turbulent conditions and took precautionary measures, including keeping the seatbelt sign illuminated throughout the flight and requiring cabin crew to remain seated.
During cruise, a sudden and severe turbulence event occurred. Flight data indicates rapid vertical acceleration changes, moving from approximately +1.0G to -0.27G and then to +2.03G, consistent with a significant up-and-down motion of the aircraft.
A passenger seated towards the rear of the aircraft was lifted from the seat and then forced back down, resulting in a serious lower back injury.
The injury was not reported immediately and was confirmed several days later following medical examination.
Weather analysis indicates the aircraft was operating in an area of unstable atmospheric conditions, including convective activity and vertical wind shear.
Although continuous light turbulence had been expected, the severity of the vertical disturbance encountered exceeded the conditions anticipated by the crew.
Importantly, the crew had already implemented appropriate mitigations. The seatbelt sign illuminated throughout the flight and cabin crew secured for safety.
The investigation determined that the primary factor leading to injury was not the aircraft response itself, but the effectiveness of restraint. The passenger was wearing a seatbelt, but the seatbelt was not tightly secured across the hips. During the turbulence a negative G phase lifted the passenger from the seat, followed by positive G forces forcing the body back into the seat structure. This sequence resulted in a compression fracture of the lumbar spine.
This event reinforces a well-established but frequently underestimated risk. A seatbelt that is fastened but not tightened may provide limited protection during vertical acceleration events.
To be effective, seatbelts must be positioned low across the pelvis and firmly tightened with no slack.
Photo Source: https://commons.wikimedia.org/wiki/File:JA05JC,_2018-07-04.jpg