Module 19 - Electronic Navigation
AIS CPA and Limitations
AIS broadcasts a vessel's identity, position, course, speed, and other data. Plotters can calculate CPA and TCPA from AIS targets, making AIS extremely useful for identifying ships and planning early avoiding action.
AIS has limitations. Not all vessels carry it, not all units transmit accurate data, small craft may use lower-power Class B units, and data can be delayed or filtered. AIS is GPS-derived, so it shares GNSS vulnerabilities. It must complement lookout and radar, not replace them.
- AIS helps identify traffic
- CPA and TCPA support early collision assessment
- Not all vessels transmit AIS
- AIS data can be wrong, delayed, or incomplete
- AIS does not replace lookout or radar
Continue studying Electronic Navigation
This public lesson is part of Revision Module 19. Full revision access adds the guided Learn, Practise and Test flow, flashcards and revision progress.