Automatic Identification System (AIS) is an automated tracking system that displays other vessels in the vicinity. It is a broadcast transponder system which operates in the VHF mobile maritime band. Your own ship also shows on the screens of other vessels in the vicinity, provided your vessel is fitted with AIS. If AIS is not fitted or not switched on, there is no exchange of information on ships via AIS. The AIS onboard must be switched on at all times unless the Master deems that it must be turned off for security reasons or anything else. The working mode of AIS is continuous and autonomous.