BIRN found more than 25 cases when satellite navigation interference was recorded over Serbia: false signals knocked down a dozen drones during protest at Slavija, while plane pilots reported that their instruments were showing them wrong information. Part of the interference came from Serbia, and part from the war zone in Ukraine, while the competent institutions refuse to publish all reports and data.
On March 15, 2025, on the day of major student protests, some pilots who landed at "Nikola Tesla" airport in Belgrade reported that the satellite signal they were relying on suddenly showed wrong data - while flying over Baฤki Petrovac and Krupanj, their instruments claimed to be in a completely different location, writes Byrne.
Novak (name changed to protect privacy) set up his DJI drone on May 23 this year at Slavia at 14 p.m. to film the student protest. Between 14:35 and 14:48, the drone lost contact with all satellites: someone sent it a false signal that convinced it to be on the runway of the Nikola Tesla airport, so, "thinking" it was flying in a restricted zone, it began to behave strangely. He was not the only one: on that day, BIRN research shows, a dozen drones were flying over Slavia and all of them were shot down in the same way.
Photo: TimeProtest in Slavija
Recurring disruption
Similar things have been happening in Serbia for years, almost as a rule on the days of large protests, elections and other politically sensitive events. By analyzing specialized databases, BIRN has identified 14 cases of interference with the Global Navigation Satellite System (GNSS) whose source is most likely in Serbia, from targeted jamming and blocking of satellite signals (jamming) to broadcasting of false navigation data (spoofing). BIRN's research shows that some interferences also came from the war zone in Ukraine - at least 11 such interferences were recorded.
Through the GPSWise.aero platform, BIRN found that false signal planting by sources in Serbia sometimes disturbed planes over 100 kilometers away as the crow flies. The pilots, BIRN has learned unofficially, have complained dozens of times to the authorities.
Alvaro Diaz Patricio, co-founder of the company Zero Industries, which programs navigation solutions for drones, indicates to BIRN that the emission of a false signal can be very dangerous for all systems that rely on satellite navigation systems, and are in the radius of its action, and that the radius is very difficult to limit for the one who emits interference.
RATEL, the body in charge of controlling radio frequencies, has submitted interference complaints to BIRN, but they claim that they have not registered any harmful interference. They were part of a request for access to information of public importance that related to announcements of interference by the MUP, BIA and the Army.
SMATSA and the Directorate of Civil Aviation refused to provide BIRN with reports of interference reported by the pilots of the aircraft.
By the way, GPS, the American system for global positioning, is only one of the global satellite navigation systems covered by the term GNSS - Global Navigation Satellite Systems. Among them are the European Union's Galileo, Russia's GLONASS and China's BeiDou. However, the name GPS is often used in everyday speech as a general term for satellite navigation.
Photo: Thomas Erhardt/PixabayDron
Disruption of drones during the protest in Slavija
Novak, name changed to protect privacy, was flying the drone on the afternoon of May 23, 2026 along a fixed route.
"I flew the drone near the Mitiฤ hole, and the idea was to take pictures of the protest (in Slavija). I flew on the route - Faculty of Law, Church of Saint Sava, Slavija, Faculty of Law - roughly from 14 to 22 p.m.," says this drone enthusiast.
The first signal hit occurred between 14:35 and 14:48, when his drone failed to establish a connection with any satellite and went into semi-manual modes. Then a false signal was played that signaled to the devices that they were at the Nikola Tesla Airport.
But this was not the only blow. The next one happened around 18:30 and 19:30, when the signal was again "thrown" by the drone at the state airport.
Novak says that the idea behind this was to neutralize the drones at Slavia because the airport is a no-fly zone. "It sends a signal to the airport or something like that, and you actually land the drone. Because the drone thinks it's in an illegal flight zone and then says to itself: 'Yeah, I'm not allowed to fly here' and descends," he concludes.
Analysis of the data from the radio station on Slavija showed that a false navigation signal was broadcast that indicated that the devices on Slavija were actually located at the Belgrade airport. These "jumps" occurred at very short intervals reporting unrealistic speeds and locations.
He adds that the disruption continued in the evening around 20:30 p.m. when the riots started.
"In the evening, it was a much bigger problem. As the conflicts started near the Assembly and the Constitutional Court, you fly there normally, you have three satellites, and then only they fall to zero in two and a half seconds," says Novak and warns that in case of loss of all signals, the drone can fall into a crowd of people and endanger safety.
An activist of the Kreni-Promeni movement, who himself operated some drones that day, says that there were about 10 drones on Slavia and that they were all shot down.
Alvaro Dรญaz Patricio of Zero Industries, a company that programs alternative navigation solutions for drones, says that broadcasting false signals cannot be broadcast by just anyone. "Such technology is intended primarily for security agencies. You can't just buy it for anyone, that would be illegal. When you use this technique, the goal is not just to disable the navigation satellite system. On the contrary, the system still believes it's receiving a valid GPS signal. You're not telling it that it's lost GPS, you're making it believe false data. It's very dangerous. Frankly, I don't see many legitimate applications for broadcasting false navigation data."
Patricio says there are far less invasive measures to neutralize drones that don't require "tampering" with essential radio frequencies.
Despite the report submitted to RATEL, which BIRN had access to, the regulatory body did not detect interference on May 23, 2026.
Pixabay / SergeitokmakovIllustration
Pilots report disturbances during March 15, 2025 protest.
BIRN has learned from well-informed sources that on March 15 last year, the day of the mass protest, pilots who landed at Belgrade's "Nikola Tesla" airport complained about interference.
"What I know is that the largest number of problems coincided with March 15. That's when there were the most reports. Five, six, seven planes reported, it was clear that something was happening. I know that after that BIA came to the Air Traffic Control of Serbia and Montenegro (SMATSA) to coordinate their jammers with those antennas with the director, and that they called telecommunications experts," the source, an expert in civil aviation, told BIRN.
Data from both specialized platforms for the detection of satellite interference, GPSWise and GPSJam, show that on that day, between 13:00 PM and 17:00 PM, both types of interference were registered in the Belgrade area and its surroundings - signal jamming and blocking, and the emission of false signals. According to the GPSWise platform, false signals affected several commercial airline flights, including Pegasus Airlines flights on the Paris-Istanbul, London-Istanbul and Amsterdam-Istanbul routes, Smartwings Hungary flight on the Budapest-Egypt route, as well as Wizz Air flights from Catania to Warsaw and from Brussels to Craiova.
For example, a Wizz Air flight still flew over Hungary when it received false navigation data, at a distance of 250 kilometers from Belgrade as a source of interference. Another Wizz Air plane was over Baฤki Petrovac at the time it also received false data, which is about 90 kilometers from Belgrade and the source of the interference. The Pegasus flight from Paris to Istanbul flew over Krupanj when it faced the same problem. The distance between Belgrade, where the jamming was launched, and Krupnje, as the crow flies, is about 100 kilometers.
"The area of โโeffect of the system can be quite large and the jamming systems work mainly at the maximum power of the transmitter for efficiency. It is possible to select the width of the jamming signal beam, the width of the range of frequencies that are jammed, the type of modulation and the strength of the signal. The planes detected interference of lower intensity because each directed beam of the jammer (meaning where the signal strength is high) can be detected with lower intensity at significantly greater distances, especially if it is a matter of airspace," the expert on radio frequencies.
A civil aviation expert who wished to remain anonymous told BIRN that "although the planes have other systems, they primarily rely on GNSS" and adds that without the correct signal, the procedure for landing planes at Belgrade and other airports becomes complicated.
Full text on this topic read on BIRN portal
Source: BIRN
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