About the GPS / GNSS interference map
GNSS RFI Monitor shows where satellite navigation (GPS, Galileo, GLONASS, BeiDou) is being disrupted by radio frequency interference. It uses the position-quality information that aircraft broadcast continuously via ADS-B, so every aircraft acts as a sensor. The user guide explains every layer, list and setting.
What the map shows
Jamming
Aircraft report not only their GNSS position but also how trustworthy it is: the Navigation Integrity Category (NIC) and the Navigation Accuracy Category for Position (NACp). When a receiver is jammed, these values drop. The map divides the world into hexagonal cells (H3 resolution 4, about 1,770 km² each) and shows, per hour or for a chosen period, the percentage of aircraft in each cell that report low integrity. Several aircraft degrading at the same time and place point to local interference.
Spoofing
Spoofed receivers compute a false position. The monitor looks for indications per aircraft and groups them into cases:
| Indicator | What it means |
|---|---|
| Position jump | The reported position moves at a physically impossible speed, and the false position persists. |
| Altitude difference | GNSS altitude differs strongly from barometric altitude (thresholds above normal temperature effects). |
| Cluster | Several aircraft report almost the same position at very different altitudes — typical of a spoofer's fixed location. |
Where possible a case is drawn as a line from the last trustworthy position (green) to the false position (red).
Filters against false alarms
Not every low value is interference. The monitor ignores aircraft that never report a good value (faulty or old avionics), aircraft on the ground or at low altitude during start-up, short single-point glitches, and the long recovery tail after an aircraft has left a jammed area. Cells with too few aircraft are not coloured. More on each method in the user guide.
Live and historical data
The live view (last 30–120 minutes, refreshed every minute) is available to registered users. Everyone can browse completed hours, days and custom ranges, and step or play through time with the timeline. History is filled from daily ADS-B archives, so gaps in the live feed are closed afterwards.
Data sources
ADS-B data from the community networks adsb.lol (Open Database License, ODbL), adsb.fi and airplanes.live, and from our own receiver. Coverage depends on volunteer receivers: over sea and in remote areas there are fewer aircraft and therefore fewer observations.
Limitations
The indicators are heuristic. A coloured cell shows where aircraft experienced degraded GNSS; it does not identify a transmitter or prove intent. Always consider the number of aircraft in a cell and whether the pattern persists over time.
Frequently asked questions
What is GPS or GNSS jamming?
Jamming is the transmission of radio noise on GNSS frequencies so that receivers can no longer track the very weak satellite signals. Receivers lose their position or report it with much lower integrity.
What is GPS or GNSS spoofing?
Spoofing is the transmission of counterfeit satellite signals so that a receiver calculates a false position or time, often far away from its real location.
How can aircraft data show GNSS interference?
Aircraft broadcast their GNSS position together with integrity and accuracy indicators (NIC and NACp) via ADS-B. When many aircraft in the same area report low values at the same time, local interference is the most likely cause. Impossible position jumps or large GNSS/barometric altitude differences indicate spoofing.
Is the map real-time?
Registered users can see the last 30 to 120 minutes, refreshed every minute. Anonymous visitors see completed hours with a short delay, and anyone can browse hours, days and custom ranges of historical data.
Does a red cell prove that someone is jamming?
No. Low values can also come from avionics faults or receiver start-up. Look at the number of aircraft in a cell and at persistence over time before drawing conclusions.
How do I get access to live data?
Open the map, choose Log in and then Request an account. You need a PIN code from the administrator; after approval you can log in and use the live view.
Regional statistics, updated every hour: GPS jamming hotspots — for example the Baltic Sea, Black Sea and Eastern Mediterranean.