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AIS-disabled ships tracked through satcoms, radar
Ships that switch off their automatic identification system signals can still be tracked using radiocommunications and navigation devices
Evading detection in conflict zones has become a new skill that seafarers are learning in the recent US-Iran conflict, but turning off a vessel’s automatic identification system (AIS) signal may not be enough.
AIS provides information on a vessel’s identity, location and voyage plan unless it is switched off; however, vessels can also be tracked through their satellite communications, radar signals and through engine exhaust, if someone is actively looking and has the technology.
During the past two months, there has been a surge in reported AIS blackouts across the Middle East Gulf, including the Strait of Hormuz, raising concerns around ’zombie ships’ that appear to vanish from AIS tracking systems.
Maritime cyber-security provider Cydome has advised ship operators and managers with assets transiting high-risk waters, especially the Strait of Hormuz, that disabling a vessel’s AIS is creating a false sense of security.
“The crew believes they are hidden, while threat actors can still track and target the ship via its VSAT signature,” said Cydome chief executive and co-founder, Nir Ayalon.
“When a crew disables AIS to avoid detection, the VSAT terminal keeps on transmitting,” he warned. “The ship is invisible to coastal AIS stations, but the location remains visible to anyone with the right tools and knowledge of what to look for. This is not a vulnerability, but an actual design feature.”
Ships can also be identified from their radar outputs by satellites launched to provide tracking information to authorities.
The European Space Agency (ESA)’s Copernicus Sentinel-1 radar satellites can detect ships even when they have turned off their radar. The radar capabilities of Sentinel-1A and Sentinel-1B satellites, launched between 2015 and 2016, have been expanded through Sentinel-1C and Sentinel-1D satellites, which were each designed to carry AIS.
Each satellite comprises four antennas that capture the signals transmitted by ships, including a vessel’s identity, position and direction of passage to enable precise tracking.
As ESA stated, “A notable advantage of this radar-based monitoring is its ability to detect ships even if they are not broadcasting AIS signals.”
This is because the synthetic aperture radar instrument on each of the Sentinel-1 satellites can detect ships, which appear as bright spots in the ocean in the radar image, even when the ships are not broadcasting their identity and location.
Sentinel-1C was launched in 2024, and Sentinel-1D on Ariane 6 in November 2025.
Maritime intelligence companies and governments are using these tracking agents, along with behavioural analytics, to develop a granular view into how conflict, coercion, and digital deception are reshaping global trade in real time.
The big questions for ship operators and managers switching off AIS to evade detection are who else is capable of doing so, and how capable are they of attacking or arresting the ship?
Riviera and Metis will host the AI in Fleet Performance Management: From Data to Decisions webinar at 09:30 – 10:30 GMT+1 on 12 May 2026. Use this link to join the webinar and for more details.
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