GPS jamming vs spoofing

Jamming: noise

Satellite navigation signals arrive at the ground weaker than the background radio noise; a receiver finds them only because it knows the code each satellite transmits and correlates for it. A jammer transmits on the same frequencies with far more power than the satellites can deliver from 20,000 km up. Inside its reach a receiver loses the satellites one by one as the noise rises, its position error grows, and then it has no satellite fix at all. A small transmitter can do this over tens of kilometres at altitude, because an aircraft has line of sight to a far wider patch of ground than a car does. Jamming is crude, obvious to the receiver, and easy to notice: the position quality falls and the receiver says so.

Spoofing: a lie

A spoofer transmits counterfeit satellite signals, correctly coded, slightly stronger than the real ones. A receiver that locks on to them computes a position and a time that the spoofer chose. The civil signals carry no signature, so most receivers cannot tell a real satellite from an imitation. Spoofing is harder to do than jamming and harder to notice: a receiver that is not checking its satellite fix against another source may believe the false position entirely. Modern airliners do check, against inertial units and ground radio beacons, and when the sources disagree the crew gets a warning and the aircraft stops trusting the satellite fix, sometimes for the rest of the flight.

How each appears in ADS-B

Every ADS-B position message carries a Navigation Accuracy Category for Position, NACp, a bound on how far the aircraft believes its reported position may be wrong. Jamming lowers NACp directly as the fix degrades. Spoofing lowers it when the receiver detects the disagreement and stops trusting the fix, which on modern transport aircraft it usually does. In both cases the message says "my position is uncertain to 0.05 nautical miles or worse", which is what this map counts, hexagon by hexagon, across every aircraft that crossed it in a day. The data cannot say which of the two caused it. The map's area with the longest run of both, by the accounts of its regulators, is the Eastern Mediterranean:

From flights on 7 November 2026, 28.3% of the monitored areas in the Eastern Mediterranean showed interference (97 of 343), 28 of them high. The region page has the day's detail.

Telling them apart

Two things help. Aircraft tracks: a spoofed aircraft that believed the lie reports a position that jumps, often to the same false spot, which researchers have used to map spoofing from the same open data; this map does not draw tracks, so it does not see that case. And published attribution: Finland's Traficom, the Baltic and Polish authorities, EASA and others have said, in their own words, which incidents they regard as jamming and which as spoofing. The region pages quote them with their sources, and the map itself never attributes. The GPS spoofing map page lists the patterns that recur when spoofing is reported; the causes page lists what else lowers accuracy, including solar storms, military exercises and older equipment.

Other public maps

Each description is taken from that map's own published explanation, read on 8 November 2026, and not checked by us beyond that. All four read the aircraft's own ADS-B reports, not ground sensors, so none can see interference that reaches only the ground.

All of them, this one included, read the aircraft's own report of its accuracy; none can see a spoofed receiver that was fooled, and none should be read as attributing a cause. For how this map is made, thresholds and limits, see the methodology; to read a day on it, see how to read a GPS interference map.