There are some numbers and sometimes even letter at the beginning of every runway in the world – you might have noticed it while travelling or in some movies. But do you know what these numbers actually mean? Are they important for pilots? It turns out, most guesses are incorrect and their actual purpose is rather simple.

There are always two digits on every end of the runway. (Adrian Pingstone via Wikimedia)

People oftentimes think that these numbers are unique titles of every single runway in the world. But that couldn’t be further from the truth. If they would be unique, they wouldn’t have just two digits. They aren’t somehow chosen by the airport either, so what are they for?

They are painted for navigation purposes. As you know, Earth has magnetic poles that are easily detected by a simple compass. Pilots always know to which direction they are heading by degrees between their course and Earth’s magnetic pole. That is actually what these numbers on runways are – they show degrees between the centerline of the runway and magnetic north. It will all make sense when you watch the video.

“L” means that this is the runway on the left. (Olivier Cleynen via Wikimedia (CC BY-SA 4.0)

And what about those letters? They are needed in case the airport has several parallel runways. They have to be marked, because their numbers are the same. So these letters help pilots knowing which runway is cleared for them to land on.

Captain Joe is one of the best aviation channels on YouTube because it demystifies civil aviation. He explains why there are loops on the wing of the plane, what are those triangles above a couple of windows inside of the plane, how fuel tanks work and much more. We really encourage checking Captain Joe’s channel out.


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