AIS spoofing is the deliberate manipulation of transmitted identifying or voyage information to conceal a vessel's movement or identity. It involves broadcasting false data rather than experiencing technical faults or legitimate operational adjustments.
Missing or incorrect AIS information can stem from several sources that are not malicious. These include poor transmission conditions, sensor or configuration faults, stale manual input, and deliberate disablement for safety reasons. It is also distinct from a legitimate VTS synthetic vessel target, which is a clearly identified radar track broadcast by a Vessel Traffic Service for a ship that does not carry AIS. Similarly, a virtual AIS aid to navigation is an official mark presented at a reported position, not a claim that a physical ship exists there.
Because AIS is an open, unencrypted system, false or ghost targets are technically possible. UK OFSI guidance defines the outcome as manipulation allowing a ship to broadcast different identifying information, potentially concealing its next port of call. However, discrepancies should be assessed against radar, visual observations, and other available safety information rather than treated as proof of spoofing, purpose, or actor. USCG guidance advises corroboration and reporting rather than reliance on the AIS display alone.
