What is AIS?
Automatic Identification System (AIS) is a maritime VHF radio tracking system that broadcasts a vessel’s identity, position, course, speed, navigational status, and voyage details. Ships, vessel traffic services, port authorities, pilots, shipping lines, and terminal operators use the feed to understand vessel movement in near real time.
In a container terminal, the tracking feed is useful because vessel schedules rarely stay static. A change in arrival time can affect berth occupation, crane start, labor call-in, export stack readiness, import delivery planning, reefer preparation, and gate appointment demand. The system does not manage containers, but it gives planners an earlier signal that the vessel plan may need to change.
Where the tracking feed is used in a terminal
Terminal teams usually use vessel tracking data alongside the proforma schedule, berth plan, port call updates, stowage information, and terminal operating system records. Typical uses include:
- Berth planning: checking approach speed, anchorage status, pilot station arrival, berth readiness, and likely alongside time.
- Quay operations: aligning quay crane allocation, labor gangs, hatch cover handling, lashers, and start times with the actual vessel movement.
- Yard planning: preparing export stacks before loading and reserving suitable import areas before discharge begins.
- Gate operations: adjusting delivery forecasts or appointment windows when discharge starts later than planned.
- Port coordination: keeping terminal control, marine operations, pilots, tugs, and shipping line representatives aligned on the same vessel status.
The feed becomes operationally valuable when it is converted into events and decisions. Raw map positions are not enough for terminal execution; planners need to know whether the vessel is approaching, waiting at anchorage, shifting berth, alongside, under operation, or sailing.
How the workflow usually works
- The vessel broadcasts data such as MMSI, IMO number, vessel name or call sign, position, heading, speed over ground, course over ground, navigational status, destination, and ETA.
- Receivers collect the signal from port antennas, coastal networks, satellite feeds, or commercial data providers.
- The terminal compares the signal with the berth window, line schedule, pilot order, previous port status, and any harbor master updates.
- If the vessel slows down, anchors, changes rotation, or approaches earlier than expected, planners revise berth occupancy, crane allocation, labor start, yard preparation, and gate assumptions.
- Actual vessel events are recorded and reconciled, such as arrival at anchorage, pilot on board, first line, all fast, first move, last move, unberthing, and departure.
In integrated planning environments, the feed is often consumed through an API and matched to vessel calls using IMO number, MMSI, service, voyage, and port rotation. It should support decisions, not replace confirmed instructions from the port authority, harbor master, shipping line, or terminal control.
Operational example
A 9,000 TEU vessel is planned to berth at 06:00, with the first crane starting at 07:00. During the night shift, the tracking feed shows the ship has reduced speed and is unlikely to reach the pilot station before 09:30. The berth planner checks the port call update and confirms a delay caused by congestion at the previous port.
The terminal moves the crane start to 10:30, reassigns one crane to a vessel already alongside, and delays a yard rehandle sequence that was only needed after discharge began. The gate team also adjusts import delivery expectations for containers from the delayed call. The plan is still disrupted, but the terminal avoids several hours of idle quay labor, unnecessary yard equipment movement, and premature gate demand.
Common fields and parameters
- MMSI, IMO number, vessel name, and call sign
- Latitude and longitude
- Speed over ground and course over ground
- Heading and rate of turn, where available
- Navigational status, such as underway, at anchor, moored, or restricted maneuverability
- Destination and estimated time of arrival, if entered and maintained correctly by the crew
Update frequency depends on vessel speed, transponder class, receiver coverage, satellite latency, and provider processing. In dense port areas, updates may be frequent, but duplicate messages, short gaps, and delayed satellite positions are normal. Terminals should filter noise before using the data for berth or labor decisions.
Typical mistakes in terminal use
- Treating ETA as confirmed operational time. A transmitted ETA may be outdated, manually entered, or based on an earlier voyage plan. It should be checked against berth planning and port call updates.
- Ignoring anchorage and pilot constraints. A vessel close to port is not automatically ready to berth. Tide windows, pilot availability, tugs, weather, draft restrictions, and berth readiness can still change the sequence.
- Using raw position data without event logic. Terminal teams need usable milestones such as arrived anchorage, pilot on board, all fast, first move, and sailed.
- Overreacting to short signal gaps. Missing updates can be caused by receiver coverage, interference, satellite delay, or provider issues. A gap does not always mean the vessel has changed course.
- Matching the wrong vessel to the wrong call. Name changes, sister vessels, reused voyages, or weak master data can link a signal to the wrong port call.
Useful KPIs
- ETA accuracy: difference between predicted arrival and actual pilot station arrival or all fast time.
- Berth plan stability: number of berth window changes per vessel call.
- Quay labor idle time caused by vessel arrival variance.
- Crane start delay: time between all fast and first container move.
- Schedule deviation: difference between proforma arrival or departure and actual arrival or departure.
FAQ
Is the system mandatory for all vessels?
It is mandatory for many commercial vessels under international maritime rules, including most larger cargo ships. Smaller craft may not carry transponders, and requirements vary by vessel type, size, flag, and local jurisdiction.
Can a terminal rely on the tracking feed for billing timestamps?
Usually not by itself. Billing, demurrage, berth charges, and contractual milestones should use agreed operational timestamps, port authority records, terminal system events, or signed documentation. Tracking data can support investigations, but it is rarely the legal source of truth on its own.
Why does a vessel show the wrong destination or ETA?
Destination and ETA fields may be entered manually on board. They can be incomplete, abbreviated, outdated, or not updated after a rotation change. Position, course, and speed data are often more reliable than the free-text voyage fields.
How is this different from a terminal operating system?
The tracking system reports vessel movement and navigational information. A terminal operating system manages container moves, yard inventory, equipment work instructions, vessel work plans, and gate transactions. The best results come when movement data is connected to operational planning rather than viewed as a separate map.
Does it improve yard planning?
Indirectly. Earlier visibility of arrival changes helps planners adjust export stack closing, import block preparation, reefer checks, equipment allocation, and delivery forecasts. The feed informs the plan; it does not create the yard plan automatically.
