GPS ghosts shield shadow tankers

In the Gulf of Finland, an oil tanker called PATE recently broadcast a navigation track that made little sense. No official investigation has said whether the cause was equipment failure, satellite-signal interference, or deliberate deception. What the case shows is more worrying for Europe’s Baltic coast: the ships most likely to cause an environmental disaster are becoming harder to track and harder to make answerable when something goes wrong.

How a tanker becomes a ghost

Every large vessel carries AIS, the Automatic Identification System, a radio beacon that tells nearby ships and shore stations who the vessel is, where it is, and where it is heading (IMO). AIS takes its position from satellite navigation, known as GNSS. If that signal is jammed or spoofed, the AIS position can also become false. The ship on the screen becomes a ghost (IMO/ICAO/ITU joint warning).

The Baltic is already a known interference zone. EASA, the EU aviation safety agency, lists the region among those affected 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 comes the shadow fleet. According to the Finnish Border Guard, an estimated 30 to 50 shadow-fleet oil tankers pass through the Gulf of Finland every week, with dozens more 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, moving Russian oil past Western sanctions. In crowded waters, a false position is not a technical curiosity. It is a risk multiplier.

Who can warn, who can board, who can stop

Europe is getting better at spotting suspicious ships than at stopping them. The problem is not the radar screen. It is the law.

Traffic controllers can warn a ship off a dangerous course. Port inspectors, under the Paris MoU system, can board and detain a foreign vessel with safety defects once it enters port voluntarily (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 is strange. Under UNCLOS, the UN Convention on the Law of the Sea, foreign ships have the 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 linking 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 the transit-passage rules in UNCLOS (UNCLOS Part III).

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

When the spill has no address

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

Estonia’s environmental monitoring underlines the Baltic’s fragility, warning that oil pollution does not respect shipping lanes or sanctions categories (Keskkonnaportaal). Finland, Estonia, Denmark, Sweden and Germany would face clean-up costs, fishery damage and tourism losses before compensation arrives, if it arrives at all.

Nobody has published evidence proving what caused PATE’s abnormal track. No official investigation has been made public. The case is not proof of a Russian attack. It is proof of a legal weakness: Baltic states often get a clear hand only after the danger becomes concrete, after a port call, after pollution begins, or after a flag can be shown to be false. The issue is whether that gap closes before one strange track becomes an oil spill with no one to bill.