When GPS goes dark: The growing problem of airlines experiencing GNSS interference
September 6, 2025
When European Commission president Ursula von der Leyen’s flight was disrupted by GNSS (Global Navigation Satellite System) jamming while flying in Bulgaria last week, the issue of electronic interference in commercial aviation was put at the top of the news agenda.
Bulgarian authorities said the disruption was the result of deliberate jamming, which analysts have linked to Russian activity in the region.
Moscow denied any involvement. The aircraft landed safely, but the incident highlighted the fragility of satellite navigation in contested airspace worldwide.
Rising risk of GNSS interference
Von der Leyen’s experience comes amid a sharp rise in incidents affecting civil aviation.
Airlines, air traffic controllers and regulators have logged thousands of cases of GNSS disruption over the past two years.
The problem is concentrated near Russia’s borders, the Black Sea, and parts of the Middle East (as illustrated above). Pilots report either total GPS loss – caused by signal “jamming” – or more insidious “spoofing” attacks, where counterfeit signals mislead onboard systems about an aircraft’s true position.
In 2024, Finnair suspended flights to the Estonian city of Tartu after repeated GPS outages made landings impossible.
Crews at Joensuu in eastern Finland faced similar problems, while flights over the eastern Mediterranean have been tricked into displaying locations hundreds of miles off course. In several cases, controllers had to give radar headings to keep aircraft safely separated.
Disruption across Europe
Aviation groups warn that dependence on GNSS has grown to the point where prolonged interference could disrupt schedules across entire regions.
Traditional aids such as instrument landing systems, VOR beacons and inertial systems still exist, but many airports now rely on satellite-only approaches.
For air navigation, multiple systems depend on satellite signals to guide aircraft safely and precisely.
These include the Aircraft-Based Augmentation System (ABAS), Ground-Based Augmentation System (GBAS), and Space-Based Augmentation System (SBAS).
Navigation concepts such as RNAV (area navigation) and RNP (required navigation performance) use GNSS data to optimise flight paths and conduct approaches and landings.
Surveillance technologies are equally reliant: Automatic Dependent Surveillance–Broadcast (ADS-B) requires accurate GNSS input to transmit an aircraft’s real-time position to air traffic control and other aircraft.
Aircraft flight safety systems also depend on reliable satellite positioning. Tools such as the Terrain Awareness and Warning System (TAWS) and the Enhanced
Ground Proximity Warning System (EGPWS) use GNSS data to prevent collisions with terrain.
If positioning information is lost or corrupted and systems are not switched off, these systems may trigger false alerts – for example, warning of a risk of terrain even when the aircraft is safely in the air at 37,000 feet. This undermines cockpit situational awareness and poses a risk to safety.
According to industry estimates, from August 2021 to June 2024, there were more than 580,000 instances of GPS signal loss of around 18.4 million flights, a dramatic increase from earlier years.
How will the industry respond?
Regulators and industry leaders are scrambling to respond.
The European Union Aviation Safety Agency and the International Air Transport Association launched a programme last year to collect incident data and share best practices.
A report to ICAO, submitted by Denmark on behalf of European Union members, states that “the safety and security of civil aviation is being eroded by the continuing rise in cases of harmful and unlawful GNSS radio frequency interference (RFI).”
It also highlights the “ease with which transmitters such as jammers can be accessed and used, and the growing need to increase robustness and resilience of current CNS systems to GNSS interference”.
Governments are also weighing new countermeasures, from shielding sensitive flight routes to upgrading satellite networks.
For now, pilots remain the last line of defence. They are trained to revert to alternative procedures, but as the von der Leyen case showed, even the most routine approach can be thrown off by invisible electronic warfare.
What was once considered a problem for military operations is increasingly a daily hazard for civilian aviation.
