What happened
On June 25, 2022, an ANA Wings Co., Ltd. flight, operating as All Nippon Airways flight 1626, was en route from Kumamoto Airport to Osaka International Airport. The Bombardier DHC-8-402, registration JA854A, was carrying 70 passengers and four crew members.
While cruising at FL 170 over Yoshinogawa City, the aircraft encountered intense turbulence. Earlier in the flight, the crew had observed rain clouds and light turbulence, leading them to suspend in-flight services and have crew members seated. However, after the pilot turned off the fasten seat belt sign to accommodate passenger needs, the aircraft entered a zone of significant airflow disturbance.
At approximately 13:29 JST, the aircraft experienced a sudden, strong vertical tremor. Flight data records indicate vertical acceleration fluctuated between +0.2 G and +2.1 G during this period. In the aft galley, a cabin crew member was in a squatting position while retrieving water bottles. The force of the turbulence lifted the crew member's feet off the floor, causing them to fall sideways onto the cabin floor. The crew member subsequently suffered a sacral fracture and required medical transport via ambulance upon arrival at the destination.
The investigation
The Japan Transport Safety Board (JTSB) examined flight data recorder (FDR) and cockpit voice recorder (CVR) data, alongside meteorological reports. The investigation focused on the aircraft's proximity to convective clouds and the flight crew's maneuvers to avoid weather radar echoes. Investigators also analyzed the timing of the seat belt sign activation and the crew's positioning in the cabin during the encounter.
Findings
- The aircraft encountered severe airflow disturbances caused by convective clouds that had developed up to approximately 19,685 feet.
- The flight crew attempted to avoid weather radar echoes by requesting heading changes; however, the initial maneuver was insufficient due to the influence of crosswinds.
- The inadequate maneuvering to avoid convective clouds resulted in the aircraft passing too close to the weather cells.
- The cabin crew member was injured because the aircraft was shaken violently while the seat belt sign was turned off, causing the crew member to lose balance while working in the galley.