On April 25, 2006, approximately 1730 central daylight time (CDT), a twin-engine Boeing 777 transport category airplane, N789AN, operated by American Airlines, Inc., as flight 945, encountered moderate turbulence during descent into the Dallas/Fort Worth International Airport (DFW), near Dallas, Texas. There was no damage to the airplane. Visual meteorological conditions prevailed, and an instrument flight rules (IFR) flight plan was filed for the scheduled domestic flight conducted under 14 Code of Federal Regulations Part 121. One flight attendant sustained serious injuries. The remaining 2 flight crewmembers, 7 flight attendants, and 244 passengers were not injured. The flight originated from the Miami International Airport (MIA) at 1619 eastern daylight time (EDT), with DFW as its intended destination. The captain stated that he informed the cabin crew he was going to turn on the seat belt sign early because of the possibility of turbulence. Soon after initial descent from 36,000 feet, the seat belt sign was turned on. He added that about 25 minutes from DFW while at approximately 25,000 feet, he made a passenger announcement (PA) and told the flight attendants to prepare for landing. Shortly after the announcement, the airplane experienced "what I would classify as moderate turbulence at most." About 20 minutes before landing, the captain called to make sure the flight attendants were in their seats, but was informed that one of the flight attendants had suffered a broken ankle. The first officer then called to have paramedics meet the airplane at the gate. The flight landed without further incidence. The flight attendant reported that the last 45 minutes of the flight was turbulent, and the flight attendants were in their assigned jump seats most of the time. The flight attendant stated that she was closing a closet after passing out coats to first class customers when the accident occurred. She said, "I turned and fell into the closet due to the airplane dropping due to turbulence." She immediately informed another flight attendant that she thought she had just broken her ankle. According to safety personnel form American Airlines, the flight attendant sustained a dislocation and double fracture of her left ankle. The company issued weather forecast for flight 945 showed that marginal visual flight rules (MVFR) conditions would continue until the next morning over the eastern half of Texas, with scattered to broken showers continuing during the afternoon. There was no significant meteorological information (SIGMET) issued for DFW for thunderstorm activity (TSTM) or clear air turbulence (CAT). At 1753, the automated surface observing system at DFW reported wind from 350 degrees at 14 knots, visibility 10 statute miles, overcast skies at 3,700 feet, temperature 17 degrees Centigrade, dew point 8 degree Centigrade, and barometric pressure at 29.94 inches of Mercury.