Glossary
The AIS is a maritime tracking system that enables ships and shore stations to automatically exchange real-time information via VHF radio. AIS continuously broadcasts a vessel’s identity, position, course, speed, and other voyage-related data, allowing nearby ships and maritime authorities to see and identify AIS-enabled traffic in their vicinity.
Under international regulations set by the International Maritime Organization (IMO), AIS is legally required on:
These requirements are set out in Chapter V of the Safety of Life at Sea (SOLAS) Convention and are intended to improve navigational safety, collision avoidance, and vessel traffic monitoring worldwide.
Collision risk remains a persistent industry challenge. Globally, there are roughly 4,000 reported marine safety incidents each year, including collisions, groundings, fires, and machinery failures. Investigations consistently identify human factors as a major contributing element in the majority of serious marine casualties.
The AIS system was introduced to address a practical limitation in traditional collision avoidance: radar and Automatic Radar Plotting Aid (ARPA) systems could track a contact and calculate its relative motion, but they could not identify the vessel itself.
Before AIS, bridge teams relied on radar echoes and ARPA-generated CPA/TCPA calculations, combined with VHF calls based on relative bearings. In dense traffic or low visibility conditions, officers might call “the vessel on my port bow” or “the ship bearing 320 degrees.” When multiple targets occupied similar bearings, this could create uncertainty about which vessel was being addressed.
AIS attaches vessel identity directly to each target on the display. Instead of relying solely on relative position, officers can call a ship by name or its Maritime Mobile Service Identity (MMSI, or digital radio identity number), ensuring both bridges are discussing the same encounter. This reduces ambiguity in crossing situations and improves coordination when several close-quarters situations are developing at the same time.
AIS is particularly valuable in:
AIS collects data from integrated bridge sensors onboard a vessel, rather than generating it independently. Position is derived from the vessel’s GNSS antenna/receiver. COG and SOG are calculated from satellite positioning. Heading is typically supplied by the gyrocompass and ROT, where fitted, is taken from the ROT indicator. These inputs are combined and packaged into AIS messages and transmitted at intervals determined by the vessel’s speed and maneuvering status.
Static and voyage-related information, in contrast, is entered manually via the AIS unit or integrated bridge system (as earlier explained). This includes vessel identity, dimensions, destination and ETA. AISdoes not validate whether these entries are correct – it simply transmits the data as configured.
AIS does not provide continuous tracking in the way radar does. Instead, it transmits discrete position updates at variable intervals, as earlier discussed. Display systems interpolate movement between transmissions, which is why AIS targets may appear to “jump” or adjust position rather than move smoothly across the screen.
In congested waters, transmission slot allocation can introduce minor delays between updates. As a result, AIS vectors reflect the most recently received data, not live sensor feeds. Understanding this distinction helps explain why AIS targets can occasionally appear to shift or update irregularly, particularly when vessels are maneuvring.
| Area | Operational Value | Operational Risk / Limitation |
|---|---|---|
| Early Detection | Displays transmitting vessels before visual identification, especially at night or in reduced visibility, and provides identity at range supporting earlier situational assessment. | Only shows vessels that are transmitting. Non-AIS targets remain invisible to the system. |
| Identification in Congested Waters | Enables direct identification by vessel name or MMSI. Reduces VHF ambiguity and speeds up coordination in multi-vessel situations. | Relies on correctly entered static data. Misconfigured identity creates confusion rather than clarity. |
| Traffic Monitoring & VTS | VTS and bridge systems integrate AIS alongside radars for structured traffic management. Reduces repetitive reporting in mandatory reporting areas. | Performance can degrade in congested areas due to time-slot saturation. Update intervals may extend. |
| Search and Rescue | Assists in reconstructing last-known positions and identifying nearby vessels able to assist. Improves situational awareness in SAR zones. | AIS is not a distress alerting system. It does not replace EPIRB, DSC, or GMDSS functions. |
| Data Integrity | Dynamic data supports CPA/TCPA when sensor inputs are accurate. | Static and voyage fields depend on manual entry. Incorrect ETA, draught, navigational status, or vague destinations are common. |
| High-Traffic Areas | Self-organizing transmission system allows large numbers of vessels to operate on shared frequencies. | Slot congestion may reduce effective update rates. Targets can appear to pause or update irregularly. |
| Coverage | Most commercial vessels above regulatory thresholds transmit AIS. | Small craft, fishing vessels, non-compliant ships, military vessels and deliberately “dark” vessels may not appear on AIS displays. |
| Security & Authenticity | Provides declared vessel identity and movement data. | AIS messages are not encrypted. Data can be misconfigured, falsified, cloned, or spoofed. Identity should not be treated as absolute. |
| Bridge Decision-making | Adds identity and declared movement to radar targets, improving clarity in developing situations. | Risk of overreliance. CPA calculations based on AIS data should always be cross-checked with radar and visual bearings. |
Yes – the Automated Identification System can be spoofed, altered, or misused because its transmissions are not encrypted or authenticated. The system was designed as an open broadcast standard to improve safety and visibility at sea, not as a secure communication network. This means that false identity data, incorrect positions, or even entirely fabricated “ghost vessels” can be introduced into AIS feeds using freely available radio equipment or software-defined radios (SDRs, programmable radio devices that can generate AIS-formatted signals).
The Automated Identification System remains a foundational layer of commercial navigation. Orca AI integrates AIS data as a core input within its multi-sensor navigation platform , augmenting, not replacing, traditional bridge systems such as radar and ECDIS. AIS position, heading, and speed data are fused with radar, daylight cameras, and thermal sensors to generate a unified, real-time traffic picture.
Because AIS is a self-reported broadcast system, Orca AI cross-validates AIS signals against radar returns and visual detections. This multi-sensor approach strengthens situational awareness by surfacing discrepancies and identifying non-AIS targets, reducing reliance on transmitted data alone.
Motion characteristics derived from AIS data, such as COG and SOG, are analyzed together with AI-based object detection to assess and prioritize close-quarters risks. Rather than relying solely on vector lines and numeric CPA values, the system highlights and prioritizes developing close-quarters situations on screen. Visual overlays and alerts draw attention to targets that require review, while navigational decisions remain fully with the bridge team.
At the fleet level, Orca AI’s FleetView platform extends AIS visibility beyond a single vessel. Shoreside teams can review encounters, analyse navigational behaviour, and monitor risk patterns across a fleet. By aggregating AIS and sensor data from multiple ships, FleetView supports fleet-wide safety oversight and enables operators to monitor adherence to company Safety Management System (SMS) procedures. Recorded event data can be used for internal review, training, and continuous improvement initiatives.
Through the Co-Captain network, AIS data is enriched with inputs from more than 10 additional sensors and supported by secure cloud connectivity. When vessels operating along similar routes detect navigational risks – such as weather hazards, low-visibility conditions, pirate activity, marine mammals, or GNSS interference or spoofing detection – relevant alerts can be shared across the network. This enables ships following the same corridor to gain earlier awareness of developing risks, extending situational context beyond the immediate radar or visual horizon.
