Every time I’ve been to an airport and looked out the window, I see numbers and letters on the runways/taxiways. How are these numbers determined?
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Runways typically reflect the compass heading, divided by 10. (Runway 18 points approximately 180 degrees, aka south, while the other end of that same runway is named 36 as it points 360° aka north).
Parallel runways will often use a L/R suffix to mark left/right of a pair (and sometimes C for center), or just consecutive numbers.
Taxiways don’t have as strict of guidelines, but are often assigned sequentially (at large airports like JFK this easily becomes a complex layout) Two letter (or letter followed by a digit) are usually short taxiways connecting/branching off the namesake taxiway, such as those connecting to various points of a parallel runway
The main runways of any airport are a two digit number based on degrees vs. magnetic north. So runway “20” is 200 degress, runway “13” is 130 degrees. It’s not that there are 13 different runways, most airports will only have 1 or 2, even the bigger ones. This way even a completely new pilot will know how to approach an airport without prior knowledge of the exact layout.
The taxiways are are a bit simpler. Each taxiway gets a letter designation in the Phonetic Alphabet, So Alpha, Bravo, Charlie, Delta. etc. The intersections between taxiways and runways are numbered. So Alpha-2 is the second intersection on taxiway Alpha, and it might connect to runway 27, which is 270 degrees from magnetic north, or a Westerly heading.
They have numbers from 1 to 36. Those numbers represent how many tens of degrees the runway is from magnetic north.
This means that a runway in one direction is that number +/-18 in the other direction. runways 3 and 21 are the same runway in different directions for example.
Parallel runways obviously are the same number of degrees from magnetic north and thus get the same number. A letter is added to differentiate parallel runways. **R**ight, **L**eft and **C**enter. Right and left as seen from a plane going down that runway. 27R is the same physical runways as 9L.
One funny aspect of this is that since the magnetic north pole isn’t fixed some runways at higher latitudes occasionally need to be renumbered without actually physically moving.
What happens when magnetic poles shift?
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