AIS Spoofing
Falsifying a ship’s broadcast position or identity on AIS to disguise where she really is or what she really is.
AIS spoofing is the deliberate transmission of false AIS data — a fabricated position, course, MMSI or identity — to make a vessel appear to be somewhere she is not, or to appear to be a different ship. It is distinct from a simple AIS "gap", where the transponder is switched off entirely.
Spoofing is a hallmark of sanctions evasion and dark-fleet operation. Detecting it relies on cross-checking AIS against satellite imagery, physics (impossible speeds or jumps) and duplicate-identity signals.
On The Maritime
Also known as: AIS spoofing, spoofing, AIS manipulation.
Related terms
Automatic Identification SystemAIS
A VHF transponder system that broadcasts a ship’s identity, position, course and speed for collision avoidance and tracking.
Dark Fleet
Ageing, opaquely owned and often uninsured tankers that move sanctioned oil while disguising their movements.
Sanctions
Government measures restricting trade or dealings with designated entities, vessels, cargoes or jurisdictions.
Maritime Mobile Service IdentityMMSI
A nine-digit number identifying a ship’s radio station, used by AIS and distress systems — distinct from the permanent IMO number.
Plain-English reference definition — our own explanation of a standard shipping concept, not a licensed source or legal advice. See the full glossary or the broader maritime dictionary.
Last reviewed: June 2026.