How to read a GPS interference map

The hexagons

The world is divided into flat-topped hexagons about 45 km across. For each one, the map counts the aircraft that crossed it during one UTC day and how many of them reported, at least once inside it, a position accuracy of 0.05 nautical miles or worse (ADS-B NACp of 7 or less). The colour is that share: green under 3%, yellow 3 to 10%, red above 10%, purple above 50%. A hexagon with fewer than three aircraft isn't drawn. Click any hexagon on the live map for its own numbers.

The blank areas

Blank means no reading, not no interference. Most of the oceans, the poles, much of Africa and central Asia, and any airspace closed to civil traffic have too few aircraft with ADS-B receivers below them to count. A blank hexagon beside a red one says nothing about the blank one. The region pages say how many hexagons had enough traffic that day, and the methodology describes where the receivers are.

The day bar

The map is rebuilt once a day, at about 04:40 UTC, from the whole of the previous UTC day's flights, and the date shown is the flight day. The bar at the top steps back through every saved day. The same days are listed under days, each with its own page, a region table and a citation, and the API serves them as JSON. A day is never revised once saved, so a figure quoted from a day page can still be checked years later.

The figures

Every page states its figures the same way: how many hexagons had enough traffic, how many of those were red and yellow, and the share. The front page ranking counts each red hexagon once, in the first region that holds it, so the regions and the hexagons outside them add up to the world total. A region page counts every hexagon inside its own boundary, and boundaries can overlap, so a region's figure can be higher than its line in the ranking; the page says so. The Baltic Sea today, as an example:

From flights on 7 November 2026, 29.5% of the monitored areas in the Baltic Sea showed interference (568 of 1,926), 220 of them high. The region page has the day's detail.

Three mistakes

The first is reading red as proof of jamming. Red means many aircraft reported poor accuracy in the same place. Jamming and spoofing are the usual reasons, but solar storms, exercises, older receivers and mountain valleys can do it too, and the causes page lists them. The second is reading the map as a picture of the ground. Aircraft at cruise see a transmitter from hundreds of kilometres away, so a red hexagon shows where the aircraft were, not where the jammer is, and interference that reaches only the ground doesn't appear. The third is reading a single day as a trend. Traffic and weather move the count from day to day, so for change over time use the "Over time" chart on each region page and its worst day on record.

The GPS jamming map and GPS spoofing map pages say what this map can show about each, the map for pilots says what it is and isn't for in flight planning, and the comparison with other public maps shows how it differs from them.