In the vast ocean, the Automatic Identification System (AIS) provides the identification of the ships. Under AIS, there are transceivers installed on ships that provide information such as unique identification of vessel, speed, course, position, true bearing, radio call sign, ETA, etc. on the electronic chart display and information system (ECDIS). This set of information is used to track ships and monitor their movement for better navigation, avoiding collision, grounding, managing traffic in congested areas, and even identifying ships in distress.
Do all ships appear on AIS?
Under the International Convention for Safety of Life at Sea (SOLAS), the International Maritime Organization (IMO) has made it mandatory for all vessels undertaking international voyages and having gross tonnage 300 or more to be equipped with AIS.
Although AIS is mandatory as per the regulations when seen in terms of practice, it is voluntary. Let’s understand this voluntary practice of using AIS by ship operators.
Understanding the AIS transmission gap
The AIS transmission gap refers to the time period during which the signals from the AIS transponder of the vessel were not received, thus the vessel’s movement and location remained unknown. The question that arises is why would an AIS transmission gap occur? The reasons could be a technical failure or deliberate action.
Technically the AIS transmission gap could be due to poor coverage. In simple terms, it means the unavailability of a close terrestrial station or low satellite revisits frequency. Overcrowded areas have transmission signal collision and congestion due to which there is trouble in receiving the AIS signals. Bad weather conditions such as heavy clouds are also a factor behind lost connectivity, ultimately leading to the AIS transmission gap.
In certain volatile parts of the world such as Syria, GPS jamming is present due to which the signal transmission cannot take place and vessels would have an AIS transmission gap. Incorrect installation or mal-functioning of the AIS transponder could also lead to loss of signal and thus generating a transmission gap.
Ships going dark
Apart from the technical reasons, there are deliberate actions of switching off the AIS transponder and making ships go dark. The operators may be having a good or a bad reason to take their ship to dark. They could be involved in sanctions evasion, narcotics trade, arms smuggling, human trafficking, or any other illicit activities. As per the United Nations report “Maritime transportation is the principal mode of transporting sanctioned commodities”. Operators involved in illegitimate activities purposely turn off their AIS transponders so that they could make a voyage to sanctioned territory or perform an illegal ship-to-ship transfer without flashing on the screens of regulators or even nearby vessels.
Curiously not all deliberate AIS signal suspensions are ill-intentioned. A semi-legitimate reason for turning off the AIS transponder is to avoid pirates. When sailing through pirate-infested waters, the ship turns off their AIS transponders so that they could sail out without coming into the eyes of pirates.
Read more on different kinds of AIS manipulations.
Often due to political complications, vessels try to avoid a particular port call in a specific country and they try to sail unnoticed in those hostile waters. A good example of such a situation would be UK flagships avoiding being detected in the strait of Hormuz after political unrest happened between UK and Iran in 2019.
AIS ensures safety
Let there be any reason for going dark, switching off the AIS transponder is not a safe practice as it puts the life of crew and vessel at risk. AIS mitigates risk, and going dark, not only makes the ship suspicious but it also raises red flags for bankers, insurers, and trade analysts who use AIS data to perform risk management of shipping companies.