An AIS identity mismatch occurs when stale configured fields or invalid MMSIs create conflicting vessel names, call signs, or identifiers on a display. This discrepancy arises from data quality issues rather than deliberate deception.
AIS static identity fields include the MMSI, call sign, name, IMO number, vessel dimensions, and ship type. Several of these are set during installation and require amendment when a vessel’s identity or configuration changes. If these updates are not made, the transmitted information remains stale.
Invalid or duplicated MMSIs also occur frequently. When vessels use the same MMSI, reports from both can appear as one target jumping between positions on a graphical display. This confuses target association and creates a confusing picture for other vessels relying on received accuracy.
AIS assists identification by name, call sign, ship type, and navigational status. However, received accuracy is only as good as the transmitted information. Faulty input can mislead other vessels, but official guidance documents that one mismatch has more than one data-quality explanation. It does not establish deliberate spoofing.
