A cabin disinfection system for an aircraft, including: a sensing means (3, 11, 13) to sense the presence of personnel in one or more zones (16-19, 23-26, 28, 29, 30, 32), a predictive sensing means (3, 11, 13, 33) to sense the direction of motion of a person (31) and to predict whether that person will occupy a zone to be disinfected (18) during planned disinfection, one or more UVC radiation sources (4, 9) to disinfect the cabin, and a controller (33) to control operation of the UVC radiation sources (4, 9) dependent on sensing of personnel in that zone and the predictive sensing means (3, 11, 13, 33) predicting that a person (31) will occupy the zone (18) during the planned disinfection period.