What happened
Approximately 35 to 40 minutes before arrival, the flight entered a layer of fine cirrus clouds, resulting in instrument meteorological conditions (IMC) and occasional light turbulence. During this period, air traffic control advised the crew that their arrival at the destination airport was being amended. The captain activated the seat belt sign and notified the flight attendant of potential adverse weather.
While the aircraft was in level cruise with the seat belt sign illuminated, a passenger and her daughter rose from their seats to use the lavatory. About two minutes after the sign was turned on, the aircraft encountered moderate turbulence lasting approximately 15 to 20 seconds; this turbulence was not detected on the weather radar display.
Following the encounter, the flight attendant discovered that a passenger had been injured. A medical emergency was declared, and the flight proceeded to Orlando. During the descent, which included transitions from flight level 280 to 240, the crew notified air traffic control of the injury. The passenger had sustained a broken foot. Onboard an emergency medical technician and a firefighter assisted in stabilizing the injury until the aircraft arrived at the gate, where ground EMTs took over care.
Findings
Radar data indicated the aircraft was at a mean sea level of 27,400 feet at the time of the incident.