AIS claims are verified by cross-checking them against independent observations, primarily radar and visual evidence, to confirm accuracy. This process is essential because the system’s built-in integrity tests only report equipment malfunctions and do not validate the accuracy of connected sensor data. Consequently, routine checks and corroboration remain necessary for reliable situational awareness.
AIS target position and motion are supplied by the target's own equipment, whereas radar provides measurements relative to the observer’s vessel. Because these two sources operate independently, they may disagree, requiring officers to cross-check the data carefully. Shipborne AIS information is divided into static data, automatically sensor-updated dynamic data apart from manually entered navigational status, and manually maintained voyage-related data.
It is critical to recognise that AIS does not prevent collisions by itself and does not replace visual lookout, radar plotting, use of all available means or compliance with the COLREG. A discrepancy between AIS and radar is not proof of spoofing or intent, but it does signal a need for further verification using all available means.
