Automatic Identification System (AIS) data is the most widely used dataset for vessel tracking. Mandated under the International Convention for the Safety of Life at Sea (SOLAS), AIS requires vessels over certain sizes to broadcast key information including identity, position, speed, and course. These broadcasts are made over VHF radio frequencies and are essential for tracking vessel movements globally.

Coverage

AIS coverage is extensive. All vessels over 300 gross tonnes (GT) engaged in international voyages are required to transmit AIS signals. This creates a global dataset encompassing the vast majority of active commercial shipping movements.

AIS data can be received via:

• Terrestrial receivers (shore-based)

• Satellite receivers (for global/oceanic reach)

• Vessel-based receivers (dynamic relays)

Transmission intervals vary from real-time to once every 24 hours, depending on configuration and reception method.

Sources

AIS signals are collected from a combination of:

• Terrestrial networks – offering high-resolution data near coastlines and ports.

• Satellite constellations – providing ocean-spanning coverage.

• Dynamic vessel relays – increasingly used to improve coverage in congested or remote areas.

Commercial data providers aggregate and process these signals to produce structured datasets used across the maritime sector.

Methodology

AIS data is generated when a vessel’s onboard transponder broadcasts information via VHF. These broadcasts are received by various networks and consolidated into time-stamped vessel position reports. Cleaning and interpolation techniques are applied to enhance the usability of the data.

Data can be structured to reflect:

• Vessel identity and technical characteristics

• Voyage data (speed, course, and navigational status)

• Geographic movements over time

Why This Data?

AIS data is fundamental to the maritime domain:

• It underpins fleet monitoring, compliance checks, port call predictions, and trade flow analysis

• It enables improvements in supply chain efficiency, environmental monitoring, and security risk detection

However, while AIS provides exceptional transparency, its ubiquity has reduced its standalone value for new insights. To derive unique outputs, AIS is best used in conjunction with other datasets to address specific challenges and objectives.

Challenges include:

• AIS manipulation (spoofing, disabling signals)

• Coverage limitations in remote or congested areas