AIS, the Automatic Identification System, is the transponder system through which ships continuously broadcast their identity, position, course, and speed over VHF radio. Mandated by the SOLAS convention for most commercial vessels, its signals are received by coastal stations and satellites, enabling global vessel tracking.
Each broadcast carries the ship’s MMSI plus navigational data; static messages add name, dimensions, destination, and draught. Designed for collision avoidance, AIS became the raw feed of commercial vessel-tracking once terrestrial and satellite receiver networks made the broadcasts collectable at scale.
AIS has honest limitations: destination fields are typed by crews and often stale, coverage has gaps mid-ocean between satellite passes, and transponders can be switched off or, in contested regions, spoofed. It is evidence of where the ship is, not a carrier’s promise about your cargo.
Container events tell you what happened at ports; AIS fills the ocean between them. TrackingMCP joins carrier milestones with the carrying vessel’s AIS track, so a quiet week mid-passage still shows a moving ship and a grounded ETA forecast in tracking, and queues at anchorages appear before any carrier notice mentions them.
AIS, the Automatic Identification System, is the transponder system through which ships continuously broadcast their identity, position, course, and speed over VHF radio. Mandated by the SOLAS convention for most commercial vessels, its signals are received by coastal stations and satellites, enabling global vessel tracking.
Under SOLAS, ships of 300 gross tonnage and over on international voyages, cargo ships of 500 and over generally, and all passenger ships. Many smaller and inland vessels carry it voluntarily or under regional rules.
Coverage gaps between satellite passes, congested VHF zones, or a transponder off. Gaps of hours are routine mid-ocean; prolonged silence near known routes merits scrutiny.
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