Satellite navigation service interferences in Finland | Traficom
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Satellite navigation service interferences in Finland

September 30, 2024 at 8:47, updated April 21, 2026 at 14:45

This situational picture describes the overall current situation of satellite navigation service interferences in Finland. It provides aggregated information on interference based on Traficom's statistical monitoring and is updated as necessary. The data is produced by the Finnish Transport and Communications Agency Traficom.

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Global Navigation Satellite Systems (GNSS) are used in many critical areas of society, such as rescue and logistics on land, at sea and in the air. Many applications on smart phones and smart devices also use satellite positioning. The best-known satellite navigation systems are the American GPS, the European Galileo, the Russian GLONASS and the Chinese BeiDou. Satellite navigation services facilitate operations and increase safety in many sectors.

Traficom is responsible for monitoring the use of frequencies and of interference analysis in Finland.

Traficom's mission is to ensure the efficient and undisturbed use of the radio spectrum. Traficom monitors the use of the spectrum and eliminates radio interference on the basis of incident reports received or its own monitoring. Traficom's responsibilities cover all types of radio traffic and frequency bands, including interference detected in GNSS services.

Traficom has the capability to detect and locate signals that may interfere with satellite positioning throughout Finland, and a comprehensive picture of interference on land, at sea and in the air. The agency closely monitors the performance of satellite navigation services and, in its role as the transport safety authority, will also react to any interference, if necessary.

Traficom monitors all GNSS frequencies throughout Finland and also receives automatic alerts in case of anomalies from land areas. The monitoring also covers the marine areas of the Gulf of Finland.

Satellite navigation services are susceptible to interference, as the satellite signal is very weak when it reaches the ground.

In people’s normal GNSS reception, such as by smartphones and smartwatches, environmental shadow areas are most often the cause of positioning anomalies. In a shadow area, the satellite signal is attenuated so much as to be inaudible or is distorted by reflections. Positioning accuracy is then reduced or completely blocked.

Space weather phenomena, such as solar storms, are natural sources of interference that reduce the availability or quality of positioning services. A solar storm can distort a satellite signal in the atmosphere, affecting positioning on the ground.

Radio interference can also impair or prevent positioning. Interference or positioning anomalies can be caused by unintended factors, such as faulty or high-powered electrical or radio equipment near the satellite positioning receiver. If the interference is caused deliberately, it is called jamming. From a system perspective, it is always radio interference, regardless of its source.

In addition, receivers may also experience programmatic interference. In addition to satellite signals, smart devices use other methods for positioning, such as Wi-Fi and the location database of smartphone apps.

In maritime and coastal areas, positioning failures are often caused by the same factors – the receiver's own interference and faulty electrical or radio equipment. However, in open sea areas, interference from shadow areas is less frequent unless there is a physical obstacle next to the antenna.

In intentional interfering, the signal is blocked by sending a stronger signal than the original one (that is called jamming), or by distorting the signal (that is called spoofing). Intentional interference with radio communications is prohibited by national law and also by international spectrum regulation.

In conflict areas, radio frequency jamming can be used to protect critical infrastructure, which is called self-protection. In international aviation, for example, interference suffered by aircraft satellite navigation systems has been observed for years, particularly in the vicinity of conflict zones. Self-protection jamming can be used to prevent, for example, GPS-guided drones from reaching their target. As a side effect, self-protection jamming can affect the navigation of aircraft or vessels in open sea areas up to several hundred kilometres away, depending on the conditions of radio wave propagation, and on the ground up to dozens of kilometres away if the environment is sufficiently open.

The accuracy of satellite navigation systems varies depending on the technology used, the user's equipment and the environmental conditions.

In general, satellite positioning systems typically have an accuracy of a few metres. In addition to location information, the services provide accurate time information to an accuracy of around 100 nanoseconds.

However, the accuracy of the location information can vary greatly, depending on the operating environment and conditions. The position solution is always calculated by the receiver on the basis of the satellite signals received. Several factors influence the quality of a position solution such as GNSS satellites' own orbital and clock deviations, distortions of the signal caused by the ionosphere and troposphere in the atmosphere and, importantly, reflections or signal attenuation caused by the operating environment, such as buildings or trees.

In consumer use, for example in smart devices, the positioning accuracy of a GNSS receiver is typically around 5 metres but, due to the factors mentioned above, the accuracy can sometimes vary significantly, up to hundreds of metres or more. Momentary, large positioning errors occur, especially in the early stages of navigation when the device is only starting to acquire GNSS signals. 

Traficom also monitors the accuracy of GNSS systems in Finland. In Finland, positioning accuracy is at a good level. Horizontal accuracy is largely in the order of 1–3 m with Galileo, GPS and Beidou. The accuracy of Glonass is at the 6–7-metre level when measured with professional equipment. Accuracy is broadly at the same level throughout Finland.

The effects of radio interference can be mitigated or prevented by various technical means such as: 

  • Positioning the receiver and antenna away from other radio or electrical equipment
  • Placing the receiver and antenna in an open space
  • Using multi-frequency receivers. Modern devices receive signals from several GNSS systems (GPS, Galileo, Glonass, Beidou), so interference with a particular frequency or system does not prevent navigation 
  • Certain technical solutions for the receiving antenna can reduce interference effects, for example by placing the receiving antenna on a mast to protect it from signals from the sides or from reflections 
  • The use of multiple GNSS receivers - for example, in ships or buildings, placing receiving antennae on different parts of the hull or building to provide more reliable positioning and GNSS time, even in the event of interference.

In-flight GPS interference in aviation

Before March 2022, GPS interference in aviation in Finland was rare. At the beginning of March 2022, however, there was a period of a few days during which numerous incidents were detected in Finland. The situation then calmed down until January 2024 when interference started in southern Finland and has continued on a daily basis since then. Typically, air navigation service providers and Finnish airlines report incidents detected in Finnish territory to Traficom. Finnish airlines also report incidents abroad. 

Year202220232024*20252026 (by the end of February)
Total612362 8001704421

* From 1.5.2024, the criteria for reporting to Traficom were revised, as GPS interference has become so common over the last few years that reporting every incident does not provide additional information on the phenomenon. The current criteria are also more in line with the reporting criteria of other EU countries. This change is reflected in the statistics as a decrease in the number of reports since May 2024.

In addition to occurrence reports, Traficom also monitors the evolution of the GPS interference situation in aviation using other sources of information, such as Traficom's own frequency monitoring and ADS-B data transmitted by aircraft. 

The impact of GPS interference on aviation safety

Aircraft have alternative navigation systems that are used when GPS signals are not available. With the help of these and, if necessary, air traffic control, an aircraft can safely navigate to its destination or to an alternate airport Airports have traditional ground-based approach systems that do not require a GPS signal.

While backup systems allow safe navigation, managing GPS interference does create an extra workload for flight crews. Similarly, the workload of air traffic controllers increases if several aircraft have to rely on air traffic control assistance. The GPS signal also provides accurate time information, which is used in many aircraft systems. Interference can therefore also affect aircraft systems other than just navigation. 

GNSS interference in waterway transport

In waterway transport, there were hardly any GNSS interference reports from Finnish territorial waters before 2024. During the summer of 2024, GNSS interferences became more frequent, especially in the eastern Gulf of Finland. Interference causes interruptions in GNSS reception and reduce the reliability of positioning. In waterway transport, the observations and reports have mainly come from professional seafarers. Individual announcements from recreational sailors has been received. The majority of the incidents have been reported in the Kotka-Hamina area due to the proximity of the area to the Russian border and the high volume of vessel traffic. All GNSS interferences for waterway transport has been reported from the Gulf of Finland.

Year202420252026* (by the end of March)
Total23823127

* On 1 January 2026, the method of compiling statistics on interference reports was changed: instead of the number of interference reports, the number of vessels experiencing interferences is published.

In the professional maritime sector, vessels use many GNSS receivers and other navigation methods, the most important of which is radar. These can help vessels to navigate safely despite interference. Checking the condition of the equipment and cabling as well as optimal antenna placement can help to achieve the best possible GNSS reception.

For shipping in the Gulf of Finland, vessels should be prepared for momentary or regional GNSS signal interruptions. Good seamanship skills should be maintained and navigation without satellite-based navigation aids is a good practice. Much of the equipment on board may be dependent on GNSS, which is something to be aware of when guarding against interference. For example, a radar plotter may use a GNSS-based compass to determine the direction of the vessel meaning that, in the event of a disturbance, the view may start to rotate.

Fintraffic's vessel traffic service, or VTS centres, control vessel traffic along the Finnish coast and on the busiest inland waterways, improving safety in case of incidents.

Preparation and Actions Onboard in GNSS Interference Situations

  • Be aware of the risk: GNSS interference can occur anytime and anywhere in the Baltic Sea. Highest risk in in the Gulf of Finland.
  • Monitor maritime safety warnings actively!
  • Identify dependencies: Know which onboard systems rely on GNSS data (e.g., position, heading, speed, time).
  • Use alternative systems: Regularly use navigation methods that don’t depend on GNSS, such as radar and paper/electronic charts. Use gyrocompass and log as needed.
  • Create a contingency plan: Prepare and practice alternative procedures for navigation during GNSS disruptions.
  • Recognize interference: Learn to detect GNSS interference, both spoofing and jamming. Not all disruptions mean total signal loss and during spoofing the navigations systems may fail to detect the spoofed information.
  • Know support along the route: Include in your passage plan the stations (e.g., VTS and SRS centers) you can contact if GNSS becomes unreliable.
  • Switch to visual and radar navigation: If GNSS is compromised, use manual steering. If gyro information is not available, use Head-Up radar mode. Disable navigation functions requiring heading input if needed.
  • Report incidents: Notify coastal state authorities (e.g., VTS and SRS) of any interference detected.
  • Stay aware of others: Even if your ship is not affected, nearby vessels may be experiencing GNSS interference. Remain vigilant and be prepared to assist or adjust accordingly.

Terrestrial GNSS interference

Terrestrial radio interference can be visible to an individual person, for example, if a smartwatch, navigator or chart plotter shows a wrong location or has only intermittent positioning. In 2024, Traficom received five reports of terrestrial GNSS interference. In all these cases, a cause other than radio interference was found.

Traficom detects low-power jammers regularly

Traficom regularly detects low-power jamming transmitters, or so-called jammers, in its own monitoring of spectrum use. Typically, these are small radio transmitters used in cars or other vehicles to mask the location of, for example, the vehicle, a tachograph or a phone. 

Because the signal from radio navigation satellites is very weak when it reaches the ground, it is easily masked by a low-power jamming transmitter. In practice, the signal emitted by a jamming transmitter interferes with or completely blocks the reception of the GNSS signal from space, making it impossible for the GNSS receiver to determine the position reliably. 

As a general rule, such equipment intended to interfere with the use of frequencies may not be used, imported, marketed, sold or transferred to another person anywhere in the EU. Unlawful interference with radio communications is also prohibited by law and is punishable under criminal law. 

Jammers can cause interference to other satellite positioning services within their range, which varies from tens to hundreds of metres. Traficom works to locate and deactivate such devices through incident reports and cooperates with the police when necessary.

Jammer sightings are made all over the country, but no related radio interference has been reported to Traficom. However, such small jammers can cause interference to GNSS reception in their area of influence, which is why Traficom is working to identify and eliminate all possible cases.

Year20232024*20252026 (by the end of March)
Total71427212144

* Detection rates decreased in 2023 as jammers were deactivated when the issue gained media visibility.

Reporting radio interferences

Radio interference and GNSS reception anomalies should always be reported to Traficom. Based on these reports, the agency's own situational information is refined and a case-by-case interference investigation is conducted.

Submit a notification of radio interference