What happened
During the arrival descent, an MD-80 was descending through 12,000 feet at speeds between 280 and 290 knots when it encountered a sudden updraft. The captain reported that the aircraft had just entered the cloud tops when the turbulence occurred, lasting approximately two seconds.
During the encounter, a flight attendant located in the rear of the aircraft was thrown from her feet, resulting in serious injuries. Additionally, a passenger who was in the lavatory at the time of the event reported hitting his head, though he sustained only a minor injury and refused medical treatment.
The flight crew declared an emergency following the incident. The aircraft was cleared for an immediate approach and landed without further incident. Upon arrival, medical personnel met the aircraft; while the passenger declined care, the flight attendant was transported to a hospital where she was diagnosed with broken ribs, a fractured wrist, and pelvic fractures.
Findings
At the time of the turbulence, the seatbelt sign was illuminated. While no storms were present directly along the flight path, SIGMETs had been issued for severe storms in the surrounding area. Notably, another MD-80 reported experiencing severe turbulence along the same route approximately 15 minutes after this event.