On September 18th, 2012 at approximately 1230 EDT, an Airbus A330, N273AY, operated by US Airways as flight 707 from Frankfurt, Germany (FRA) to Charlotte, NC (CLT) encountered severe turbulence on descent into CLT. During the encounter, a flight attendant was seriously injured. According to the operator, on descent into CLT the flight crew received an ACARS message from the company dispatcher handling the flight. The dispatcher indicated that a SIGMET was issued for the North Carolina area with strong winds and embedded thunderstorms. The International Relief Officer (IRO) contacted the flight attendants to advise them they would be entering an area of possible turbulence in approximately 15 minutes. An announcement was also made to the passengers over the public address system advising them to remain seated and fasten their seat belts. The seat belt sign was illuminated. The airplane was descending through approximately 16,000 feet when it entered the clouds and encountered moderate turbulence. In the cabin, the flight attendants began preparing the cabin for arrival after receiving the turbulence advisory from the IRO. Several flight attendants were still out of their seats collecting service items and securing the galley when the turbulence encounter occurred. The "C" flight attendant was securing the aft galley during the encounter. She was lifted into the air, fell back down onto the cabin floor, and landed on her back. The "D" and "G" flight attendants also sustained minor injuries. The flight crew contacted the flight attendants after the encounter and were notified of their injuries. The flight crew arranged for paramedics to meet the flight and remove the injured flight attendants. The "C" flight attendant received a fracture to the distal tibia at the medial and lateral malleoli.