AIS position reports support target tracking, situational awareness, and CPA/TCPA calculations via dynamic data.
Each report carries essential information such as position, accuracy, time, course, speed and navigational status, with the position and timestamp originating from the vessel's connected sensor. Successive received reports allow observers to monitor movement patterns effectively, yet this reported data is based entirely on the transmitting station's inputs rather than an independently measured or guaranteed position.
It is critical to understand that a target's AIS position is derived from its electronic position-fixing receiver and may not coincide exactly with the target detected by radar. Furthermore, poorly configured or faulty sensors can transmit incorrect position information, and the AIS built-in integrity test does not validate the truth of the sensor data.
Consequently, while these reports are valuable for tracking, the target-supplied position may differ from the radar target and may be wrong. Operators must recognize that AIS data supplements other navigation tools rather than replacing them, ensuring that situational awareness is maintained through cross-referencing multiple sources of information.
