Ever wondered what Runway numbers mean?

I've always looked out of my plane window during taxi and noticed the giant numbers painted at the end of the runway- 09, 27, 36 - and asked, what’s going on here? Is it some sort of secret pilot code?

Not quite. Runway numbers are actually based on… compass directions! Each number corresponds to the magnetic heading of the runway, rounded to the nearest 10 degrees. So, a runway pointing east (90°) is labelled 09, while one pointing west (270°) is 27. Simple, right?

That’s why you’ll often see two numbers at opposite ends of the same strip of asphalt: they’re the same runway, just viewed from different directions. Runway 18 on one end is Runway 36 on the other, because 180° and 360° are opposite compass bearings.

Here’s a fun twist: at airports with multiple parallel runways, letters come into play. So you might see Runway 09L (left) and 09R (right), like twins on the same heading. In mega-airports, there’s even a center runway: 09C.

Of course, the Earth likes to keep pilots on their toes. Since the planet’s magnetic poles are constantly drifting, sometimes runways actually have to be renumbered to stay accurate. Imagine being told your favorite runway 32 is suddenly “33.” Aviation nerds notice.

So next time you’re on approach and the pilot says, “We’re cleared to land on Runway Two-Seven,” you’ll know: you’re about to touch down heading west, right into the golden sunset. Not bad trivia for your seatmate, either.

Image source: Niklas Jonasson (Unsplash)