When the ship says it's at the airport: shipping's position-trust problem
GPS jamming hit more than 1,100 ships in a single day this year. The damage is not only on the bridge. It reaches every desk that relies on AIS
In the 24 hours after the strikes on Iran on 28 February, Windward counted more than 1,100 ships across the Gulf with disrupted GPS signals. Some appeared on land. Some appeared at airports. One appeared inside a nuclear power plant.
It was not a one-off. Windward recorded about 978,000 jamming events worldwide in the first quarter of 2026, 98% of them in the Middle East Gulf. Across a wider area, the count of affected vessels soon passed 1,650. Marlink reported a rise of more than 50% in GNSS interference across its customer fleet between February and March.
Two problems, not one
The first problem is on the bridge. A ship that does not know where it is, in congested water, is a collision or grounding waiting to happen. Experienced officers fall back on radar, visual fixes and dead reckoning. But many modern systems quietly depend on GNSS, from ECDIS to the speed and latitude inputs that correct the gyro, to the AIS your neighbours are watching.
The second problem is ashore, and it is less talked about. Banks, charterers, insurers and P&I clubs screen vessels using AIS. When a jammed ship broadcasts a position at a sanctioned port it never visited, someone has to investigate a false alarm. When a ship that did visit broadcasts a position elsewhere, the screening misses it.
Windward found one very large crude carrier, waiting off Qatar, whose AIS signal was jammed to six different areas within 24 hours. Imagine the alert queue that produces across a whole fleet.
The position is now a data-quality question.
Windward makes a point worth repeating: jamming describes an area, not a vessel's behaviour. Being in a jammed zone is not, on its own, a red flag. Treating it as one burns analyst time. Ignoring it hides real risk.
The answer is not a better single source. It is more than one source, and software that knows how to weigh them.
What good looks like
On board: integrity monitoring that flags when GNSS disagrees with radar, gyro and log, and drills so watchkeepers trust that alarm.
Ashore: AIS cross-checked against satellite radar and optical imagery, RF detection and the vessel's own voyage history before an alert reaches a person.
In compliance: every screening decision recorded with how the position was verified, so it stands up in an audit.
In operations: jamming zones mapped and fed into voyage planning, so masters know before they enter one.
The takeaway
For most of shipping's digital era, position was a given. In 2026 it became a claim that has to be checked. The firms that build that check into their systems will spend less time chasing ghosts, and more time spotting the ships that really are where they should not be.
vi-tech builds data platforms and dashboards that combine maritime data sources, with input from a Master Mariner who has navigated without the luxury of perfect signals.
