Airports Rename Their Runways Due To Changes In Earth’s Magnetic Field



Almost every year, there's an airport in some part of the world that needs to renumber — and therefore rename — its runways due to international safety regulations. The numbers are based on the runway’s magnetic bearing, indicating their position to the Earth’s North Magnetic Pole. The North Magnetic Pole wanders constantly, by around 37 miles per year. If the compass bearing will at a some point round off to another decadegree — a decimal unit prefix in the metric system denoting a factor of 10 — the runway must be renamed based on international aviation regulations. Changing the numbers of the runways requires sign panels being replaced and the runways being repainted. The renewal is estimated to cost hundreds of thousands of dollars.