GPS Ghosts Hide Shadow Tankers

Somewhere in the Gulf of Finland, an oil tanker called PATE recently appeared to be in two places at once, or close enough for the track to make little sense. No official investigation has said whether this was faulty equipment, interference with satellite signals, or deliberate deception. But the episode points to a harder problem along Europe's Baltic coast: the ships most likely to create an environmental disaster are becoming harder to track, and harder to make pay when something goes wrong.

How a tanker becomes a ghost

Every large vessel carries AIS, the Automatic Identification System: a radio beacon that broadcasts its identity, position and course to nearby ships and shore stations (IMO). AIS takes its position from satellite navigation, known as GNSS. If a ship's receiver is jammed, or fed a false signal, the AIS message becomes false as well. To everyone watching, the ship turns into a ghost (IMO/ICAO/ITU joint warning).

The Baltic is already a known interference zone. EASA, the EU's aviation safety agency, lists the region among those hit by recurring GNSS outages (EASA). Germany's Foreign Minister Johann Wadephul has described the Baltic as a growing conflict zone involving sabotage, espionage and GPS disturbances (n-tv). Sweden's Vice Admiral Eva Skoog Haslum has linked GNSS disruption to a wider pattern of Russian grey-zone pressure on ports, sea lanes and infrastructure (Omni).

Then come the shadow tankers. According to the Finnish Border Guard, an estimated 30 to 50 shadow-fleet oil tankers move through the Gulf of Finland every week, with dozens more sitting at anchor; traffic controllers have had to warn tankers heading towards shallows (Yle). These are ageing ships with opaque ownership, flags of convenience and often unverifiable insurance, carrying Russian oil around Western sanctions. In water this crowded, a navigation anomaly is not just a technical oddity.

Who can warn, who can board, who can stop

Europe is getting better at seeing suspicious ships than at stopping them. The weakness is legal as much as technical, and the chain of authority has gaps all along it.

Traffic controllers can warn a ship away from a dangerous course. Port inspectors, working under the Paris MoU system, the agreement that lets harbour states check foreign vessels, can board and detain a ship with safety defects. But that power usually begins only when the ship voluntarily enters port (Paris MoU). A coastal state cannot simply stop a tanker at sea because it looks like part of the shadow fleet or because its tracking data seems strange. Under UNCLOS, the UN Convention on the Law of the Sea, foreign ships have a right to transit through territorial waters and international straits (UNCLOS). Stronger action needs a concrete trigger: a provable pollution danger, statelessness, or false flagging.

Denmark controls the narrow straits connecting the Baltic to the North Sea and runs mandatory reporting systems at the Great Belt and Øresund (BELTREP, SOUNDREP). It can require ships to identify themselves and keep to traffic lanes. It cannot turn geography into a blockade without running into transit-passage rules under UNCLOS (UNCLOS Part III).

The agencies involved do not close the gap. EMSA, the EU's maritime safety agency, runs satellite monitoring that can flag dark vessels switching off AIS, but it has no boarding or enforcement power of its own. National coast guards, navies and water police each hold part of the job: patrol, inspection, fines. No single body owns the full sequence from detection to intervention to the eventual bill.

When the spill has no address

If one of these tankers grounds or collides, the first cost lands on the nearest coast. Under the international compensation system, shipowners and their insurers pay first, with the IOPC Funds providing a backup layer (IMO CLC, IOPC Funds). That system works when ownership is clear and insurance is real. With shadow-fleet vessels, shell companies and unverifiable cover can leave coastal states paying for cleanup while legal claims chase paperwork through offshore registries.

Estonia's environmental monitoring underlines the Baltic's fragility, warning that oil pollution respects neither shipping lanes nor sanctions categories (Keskkonnaportaal). Finland, Estonia, Denmark, Sweden and Germany would all face some mix of cleanup costs, fishery damage and tourism losses before compensation arrived, if it arrived at all.

Nobody has published evidence proving what caused PATE's abnormal track. No official investigation has been made public. The case does not prove a Russian attack. It proves something more practical, and more awkward: Baltic states often get a clear legal hand only after the danger has become concrete, after a port call, after pollution begins, after a flag can be shown to be false. The open question is whether that gap closes before one strange track becomes an oil spill with nobody obvious to bill.