World Atlantic Airlines flight 261, from Abel Santamaría Airport (SNU), Santa Clara, Cuba, encountered turbulence during descent into Miami International Airport (MIA), Miami, Florida. As a result, one flight attendant (FA) sustained a serious injury. According to the captain, they were descending through 12,000 ft when they observed an isolated cloud formation and requested a deviation from air traffic control (ATC). While maneuvering between clouds, the airplane encountered about two seconds of severe turbulence. At the time of the encounter, the fasten seat belt sign was illuminated. After the turbulence encounter, the flight crew contacted the senior FA and were initially informed that there were no injuries and the cabin was normal. Shortly after, the senior FA called the flight crew to advise that one of the FAs had fallen during the turbulence and was experiencing dizziness. The flight continued to MIA and landed without incident. While taxiing to the gate, the senior FA contacted the flight crew and reported that the injured FA was experiencing pain on her right side. The flight crew requested paramedics to meet the flight at the gate. The injured FA was transported to the hospital and diagnosed with a concussion and rib contusion. The FA was hospitalized for four days before being released. According to the injured FA, she was seated near the galley when the fasten seat belt sign was illuminated. She was attempting to fasten her seat belt when the airplane encountered turbulence. She stated that she felt a heavy impact and lost consciousness. When she regained consciousness, her colleagues were there and she felt pain on her right side. After the accident, World Atlantic Airlines issued a safety bulletin to all inflight personnel that emphasized the importance of adherence to procedures when encountering severe turbulence, including briefings on expected turbulence during arrival and descent.