Magnets and magnetism are, to the unenlightened, akin to magic. Give a pair of magnets to a nursery schooler and they will jump in shock when the two inexplicably (to them, at least) fuse together, too tight for little hands to pry apart.
But magnetism serves other purposes — such as navigation by compass, a critical tool for airplane pilots. In landing a plane, for example, pilots are told which runway to use based, in part, on the compass reading. Runways are named using a rounded, divided by ten designation corresponding with the compass heading; “Runway 21,” for example, is located somewhere between 215 and 224 degrees.
Unfortunately, compass readings aren’t static. They’re measured from the magnetic poles of the Earth which, themselves, drift of time. The magnetic north pole, for example, moves roughly 40 miles from the North Pole toward Russia each year, caused by changes in the core of the Earth. And when where you are, per the compass, changes, so must the runway designations. These runway designation changes happen more often than you’d think: one changed in Tampa, Florida in January of 2011.
These designation changes aren’t minor undertakings. They require changes to the aeronautical maps involving the airport and related airspace — basically, a re-writing of the “road map” for air traffic around the airport — which pilots rely on to determine safe altitudes and paths in the area. And they also require that the runways, with their designations written in huge, glowing paint, be re-labeled in a way which maintains clarity, visually, from hundreds (if not thousands) of feet above ground.
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Related: Pole Position, the classic Atari 2600 game.