Runway Renumberings: How a Wandering Magnetic North Rewrites Global Airports

Earth’s magnetic north drifts as molten iron in the outer core moves, changing the magnetic bearing used to label runways. When the drift shifts bearings by about 3–4 degrees, airports must repaint runways, replace signage, and renumber designations, a process seen at Tampa, Fairbanks, London Stansted, and others. The changes are driven by updates to the World Magnetic Model and the planet’s ongoing core dynamics, even though passengers rarely notice the invisible pen-and-paint overhaul happening far below their flights.