What happened
During the descent phase of the flight, the aircraft encountered severe turbulence. At the time of the encounter, two flight attendants were standing in the cabin performing final duties in preparation for landing. The intensity of the turbulence caused both crew members to be knocked to the floor. Both flight attendants sustained serious injuries during the event.
The investigation
Analysis of the flight data recorder indicated that the aircraft experienced vertical accelerations ranging from +0.4 G to +1.9 G, representing a total change of 1.5 G. This level of acceleration is consistent with severe turbulence. The turbulence was determined to be mechanical in nature, likely caused by strong easterly winds interacting with the rough terrain in the vicinity.
Findings
Investigation into the weather information revealed that the National Weather Service had issued a Significant Meteorological Advisory (SIGMET) Victor 2, which forecasted severe turbulence for the area. This advisory was issued prior to the aircraft's departure. While the content of this SIGMET was available to the flight's dispatcher, the information was not provided to the flight crew. Additionally, the weather service provider used by the operator had not forecasted severe turbulence for the region.