# This Is What Airport Runway Numbers Mean

I’m pretty sure you’ve noticed the big numbers in the airport runways, but have you ever wondered what do they actually mean? A lot of people are under the impression that they just indicate the number of runways at the airport. But is this correct?

Well, no. Runways are numbered based on the magnetic azimuth direction (compass bearing) they are oriented to. Every runway has two numbers, one at each end. These two numbers are the reciprocal of the other (180 degrees opposite) and are determined by rounding the compass bearing to the nearest 10 degrees and removing the last digit (that’s why runways are always numbered from 1 to 36, not from 10 to 360).

By using this method you end up with two numbers which differ by 18 (since they are 180 degrees opposite from another). So, for example, if the compass heading of a runway is 93° you would round it down to 90 and drop the last digit, leaving you with 9. Therefore this runway will be called Runway 9-27 and, as you can see on the picture below, it’s oriented east-west: (the article continues after the ad)

In addition, because many large airports have parallel runways, they require further designation of each runway. Take Boston, Massachusetts’ Logan International Airport for example. It has two pairs of parallel runways: Runway 4L-22R and 4R-22L. These “L” and “R” (left or right) actually designate the relative position of each runway when approaching its direction. Some airports even have three parallel runways which give us a “C” runway (center).

So now you know! It’s just the direction they are oriented to!

### If you like what you read, then you will definitely love this one: There’s A Reason Why Pilots Dim The Cabin Lights During Takeoff And Landing

Main Article Photo: SaS 1946
Photoshop: I’m A Useless Info Junkie
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