On March 10, 2000, about 1310 eastern standard time, an Aerospatiale ATR-72-212, N636AS, registered to First Security National Bank, NA, operated by Atlantic Southeast Airlines, Inc., as flight number 4163, a Title 14 CFR Part 121 scheduled air carrier flight, sustained a serious injury to a cabin crewmember while in cruise flight 12 miles northwest of Athens, Georgia, at 15,000 feet msl. The ATP-rated pilot, the commercially-rated copilot, another cabin crewmember, and 23 passengers were not injured. Visual meteorological conditions prevailed and an instrument flight plan had been filed. The flight originated from Atlanta about 20 minutes before the accident. According to the pilot's statement, the flight was en route to Greenville-Spartanburg, at 15,000 feet msl, passing northwest of cloud buildups that did not show on the airborne weather radar, with the seat belt sign illuminated, when the aircraft passed through the edge of a cloud. The aircraft experienced a hard jolt, followed by moderate turbulence, after which the cockpit received a cabin interphone report that one flight attendant and two passengers received possible injuries. The pilot elected to continue to his destination, about 15 minutes away, and requested emergency medical personnel meet the flight. Upon landing, the two passengers were determined by medical personnel not to be seriously injured and were released. The flight attendant was transported to a hospital where it was determined she sustained fractures of the left ankle and right great toe. The aircraft was inspected for damage with negative findings. The NTSB was notified by the airline's FAA Principal Operating Inspector on March 15, 2000, that the flight attendant had sustained a slightly displaced fracture of the distal fibula of the left ankle.