AIS position reports are limited by sensor dependency, variable update rates, radar misalignment, and lack of validation. An AIS position report carries dynamic data such as position, position accuracy, time, course, speed and navigational status; position and timestamp originate from the connected position sensor. This means the reported location is entirely dependent on the quality and configuration of the transmitting vessel's onboard equipment rather than an external verification source.
A target's AIS position is derived from its electronic position-fixing receiver and may not coincide exactly with the target detected by radar. This discrepancy arises because the two systems use different reference points and update mechanisms, so users must understand that the visual or radar contact and the digital AIS tag do not always align spatially in real-time.
Position reporting intervals vary by equipment class, speed, movement and reporting mode; position reports normally arrive more often than static and voyage-related information. Consequently, relying on a single snapshot can be misleading during rapid maneuvers. 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. Users must remain aware that plausible but erroneous coordinates can be broadcast without triggering system alarms.
