AIS dynamic data supports target tracking and situational awareness by providing successive position and movement reports. With an appropriate display, these transmitted positions assist in CPA or TCPA calculations to assess collision risk.
This information includes position with accuracy and integrity indications, UTC position timestamp, course over ground, speed over ground, heading, navigational status and rate of turn where available. Dynamic position reports and static or voyage reports are separate AIS messages; the USCG identifies Messages 1, 2 and 3 as Class A position reports, Message 18 as a Class B position report and Message 5 as Class A static and voyage-related data.
Received AIS movement information assists in maintaining situational awareness. However, this data remains supplementary to visual and radar observation. AIS information should be corroborated through systematic visual and radar observation and must not replace lookout, radar plotting or use of all available means.
