Incident Details
While cruising in smooth air conditions with no clouds in the area and with the autopilot engaged and the seat belt sign off, the aircraft experienced a brief encounter with wake turbulence, as described by the flight crew. The momentary turbulence resulted in a sharp roll deviation of approximately 15 to 20 degrees. The disturbance lasted for less than five seconds before the aircraft returned to smooth air conditions.
Injuries
One of the two flight attendants who had been standing in the rear galley sustained a serious injury, while the other flight attendant received a minor injury. No other occupants were reported injured.
Weather and Conditions
No significant turbulence had been forecast for the area, and the flight crew had not overheard any other aircraft reporting turbulence. Immediately after the encounter, the aircraft continued in smooth air conditions.