ON APRIL 29TH Finnair, Finland’s national airline, said that it would suspend flights to the eastern Estonian city of Tartu for a month. Last week two planes were forced to turn around after their GPS signals were disrupted. GPS jamming has increased sharply in the Baltic region over the past two years. Who is behind it and how dangerous could it be?
Previously open-source analysts studied the positions of planes experiencing jamming to work out where the source was likely to be. They concluded that it was in Kaliningrad, a heavily militarised Russian exclave between Lithuania and Poland. In March a Royal Air Force plane carrying Grant Shapps, Britain’s defence secretary, was subjected to jamming for around 30 minutes as it flew near Kaliningrad.
But the latest jamming seems to come from elsewhere. @auonsson, a pseudonymous analyst posting on X, a social-media site, analysed data collected by amateur drone flights as well as the position of jammed aircraft (see map). The analyst concluded that the site is in mainland Russia, not far from St Petersburg. That corresponds with the approximate location of several known Russian military sites. A person familiar with private data says that there is clear evidence of Russian jamming activity in that area.
Does this mean that Russia is actively trying to interfere with European civil aviation? Probably not. European officials familiar with the issue say that the jamming is probably intended to protect Russian forces from Ukrainian drone attacks, which are growing more frequent and ambitious. On April 2nd a Ukrainian drone struck Russia’s third-largest oil refinery, 1,300km away from the front lines. On April 20th Russia said it had shot down 50 drones over eight Russian regions overnight, causing injuries in the Moscow region. The disruption in the Baltic states is probably a byproduct of Russian defensive measures. Disruption of GPS has been common in the eastern Mediterranean in the past decade, stemming from the Russian air war over Syria and, more recently, Israeli jamming to foil missile and drone strikes.
In Ukraine jamming is a crucial military tactic on both sides of the war. Russia appears to have the edge: at least three important American weapons supplied to Ukraine—the GMLRS rockets fired by HIMARS launchers, the Ground-Launched Small Diameter Bomb and precision-guided Excalibur artillery shells—have had their accuracy and effectiveness degraded by Russian jamming. Earlier this month the Centre for Defence Strategies, a think-tank in Kyiv, reported that Ukraine had ceased GMLRS attacks because their GPS guidance had been so badly degraded. Only a minority of Excalibur shells now make it to their targets.
The jamming of civil aircraft in the Baltic may be inadvertent, but it is nevertheless a pain. “There are reversionary modes for navigation and position keeping for civil aviation,” says Justin Bronk, an expert at the Royal United Services Institute, a think-tank in London. “But given the busy airspace within which they are operating, lack of reliable GPS will significantly increase the separation distances required for safety.” Leaving more gaps between planes may be essential, but it is “enormously disruptive”. ■
Editor’s note: Our A-Z of military terms explains modern warfare from “ambush” to “zapad”. Read it here.