Record GPS disruptions leave ship without signal near Bornholm

GPS disruptions near Bornholm have reached record levels this year, with cargo ship captain Jens Nielsen recently sailing for up to 24 hours without a signal, DR reports.

Nielsen owns and captains the cargo ship Saturn, which has a four-person crew and regularly transports goods around the Baltic Sea. GPS problems usually last 15 to 20 minutes, but they have recently become more severe.

On 29 July, the ship lost its connection for about a day while sailing between Gdansk and southern Gotland. During its latest trip from Gdansk back to Hundested, the crew had no signal for around 12 hours before reaching Bornholm, Nielsen said.

The problems typically occur in the southeastern Baltic Sea. When they do, the crew has to steer manually using the wheel and a magnetic compass because the autopilot stops working.

Manual navigation is less accurate, Nielsen said, and some shipping routes are marked only electronically. GPS spoofing can also show a vessel in the wrong location. On 29 July, Saturn was about 20 nautical miles north of Gdansk, but its GPS showed the ship on land near Kaliningrad.

A measuring station in Tejn on Bornholm has recorded around 30 cases of GPS jamming and spoofing this year. The total for all of last year was 16.

The measurements cannot establish where the interference originates. Søren Reime Larsen, a researcher at DTU Space who specialises in GPS jamming and spoofing, said the number of incidents had risen sharply since the war in Ukraine began in February 2022.

He said GPS is widely used in military technology, including drones and missiles, and that interference could be a defensive response. However, he said he was not aware of any cases near Bornholm that had caused serious consequences. He believes the interference is more likely a side effect affecting shipping in the Baltic Sea than a deliberate attack on Bornholm infrastructure.

Authorities in several European countries, including Denmark, have accused Russia of being behind interference with navigation systems in the Baltic Sea. In an open letter in January, they said the disruptions posed a risk to maritime safety.

Jamming and spoofing

GPS jamming involves deliberately transmitting a powerful radio signal that creates interference with the satellite signals used by electronic devices for navigation and positioning. GPS spoofing involves falsifying a GPS signal so that receiving equipment believes it is somewhere other than its actual location.

Nielsen does not expect the problems to end soon and fears they could worsen if the war in Ukraine escalates. Installing a new satellite navigation system that can use multiple signals instead of relying solely on GPS would cost about 100,000 Danish kroner.

Such a system would probably solve his immediate problems, but Nielsen said it might not be a long-term solution if those causing the interference begin targeting other frequencies. Crews may have to accept that they can no longer determine their position with the same certainty as before, he said.