What happened
The pilot received a pre-departure weather briefing that indicated conditions would include occasional moderate turbulence below Flight Level 180. However, the operational reality differed significantly from the forecast as the aircraft began its descent. While cruising and descending through Flight Level 260, the airplane encountered significant turbulence that had not been predicted in the initial briefing.
During this encounter with the unexpected atmospheric disturbance, one of the passengers was violently thrown about the cabin. The individual was in the process of returning to his assigned seat after having secured the galley at the explicit request of the pilot. The force of the turbulence caused the passenger to sustain a broken ankle during the incident.
The investigation
The investigation focused on the discrepancy between the pre-flight weather data and the actual conditions encountered by the flight crew. The captain confirmed that the aircraft was descending through Flight Level 260 when the unforecasted turbulence struck. No mechanical failures or pilot errors were cited as contributing factors to the event itself, which was attributed entirely to the atmospheric conditions.
Findings
The primary finding relates to the limitations of the pre-departure weather briefing. The forecast accurately described conditions below Flight Level 180 but failed to account for turbulence at higher altitudes. This lack of accurate upper-level weather data led to an unexpected encounter with severe atmospheric disturbance during the descent phase, resulting in injury to a passenger who was moving within the cabin.