An AIS transponder has limits in its equipment class, its fault checks and the role of its display. Class A and Class B equipment have different capabilities and reporting behaviour. Class B does not necessarily provide all functions required of Class A equipment.
The built-in integrity test can detect unit malfunction and data availability errors. It does not validate the real-world accuracy of connected sensor data. AIS can operate with a minimum display or feed radar, ECDIS and other navigation displays, but it remains supplementary to lookout, radar and all available safety information.
IMO lists the main onboard AIS components as antennas, a VHF transmitter, multiple VHF receivers, a processor, GNSS timing and redundancy, sensor interfaces, display and input facilities, and a built-in integrity test.
