On May 20, 2009, at 1230 eastern daylight time, Delta Airlines flight 419, a Boeing 767, N129DL, encountered turbulence while enroute from Atlanta, Georgia, to San Juan, Puerto Rico. The captain stated that preflight information and enroute reports indicated only light chop for the flight and he communicated this to the flight attendants. About 10 minutes before the turbulence encounter, the captain turned on the seat belt sign and made an announcement for the passengers to remain in their seats with the seat belt fastened because they would be deviating around weather ahead. After deviating around the weather and with no weather returns on the radar, the flight encountered turbulence that lasted for about 20 seconds. At the time of the turbulence encounter, the airplane was in cruise at Flight Level 350. One of the flight attendants in the back of the airplane was thrown from her jump seat to the floor and injured. Two doctors and a nurse assisted the injured flight attendant. The flight crew declared an emergency and was given direct routing to San Juan. The injured flight attendant was transported to the hospital, where she was subsequently diagnosed with a fractured femur. Probable Cause: Inadvertent encounter with convective turbulence while in cruise.