Safely using an AIS transponder requires accurate inputs and a proper lookout. It never replaces radar or visual observation duties.
A shipborne AIS unit automatically transmits its own data and receives data from other ships, VTS stations and other AIS stations over the AIS VHF data link. While this provides situational awareness, the built-in integrity test can detect unit malfunction and data availability errors but does not validate the real-world accuracy of connected sensor data. Operators must recognize that functional transmission does not guarantee correct position or speed inputs.
AIS can operate with a minimum display or feed radar, ECDIS and other navigation displays, but remains supplementary to lookout, radar and all available safety information. It is essential to maintain a proper visual and auditory lookout at all times. The system must never replace radar monitoring or the duties required by collision regulations.
