Those who are interested in aviation have seen and wondered about the numbers on both ends and beginnings of the runways, these are called “runway designators”. So, what do these numbers and letters for?
The numbers correspond to the magnetic direction in the area where the runway is located. A compass is needed to find the magnetic location. When you take a world map and put your compass next to it, you will see that 0 degrees points to north, 90 degrees to east, 180 degrees to south, and 270 degrees to west. North is usually expressed as 360 degrees instead of 0 degrees, although both mean the same thing in aviation. The compass shows 360 in the north, 180 in the south, 270 in the west and 90 in the east. Runways are named according to the value closest to the radial on the compass. The 3-digit number showing the direction on the compass is rounded down to 2 digits.
When numbering the runways, the values of the magnetic compass are used, not geographic. The reason why the runways are numbered on both sides is that planes can land and take off from both sides. The numbers of the opposite directions of the runways are 180 degrees opposite each other, so there are 18 differences between these designators. For example, consider the runway designators of London Heathrow airport, 09L-27R and 09R-27L are runways.
Well, some runway designators have the letters L, C, R and T next to them. What are these letters and what are they for?
Some airports have more than one runway in the same direction (parallel). London Heathrow airport also has two runways parallel to each other. Runways 09L-27R and 09R-27L. This means that the runway 09L is on the left of the runways in the same direction. The first letter of the word Left “L” is located next to the 09. Likewise, runway 09R indicates the right one of the two runways in the same direction (Right, “R”).
There is also a letter T other than these letters. The letter T is used in airports that are close to magnetic north. For example, Alert airport runway designators in the north of Canada are 05T / 23T.
In addition to all these, there is another issue we need to pay attention. Runway numbers can change over time, as the magnetic north shifts towards Russia at a certain rate each year. For example, the 05-23 runway of Istanbul Atatürk Airport has been changed due to the magnetic north change. Previously known as the 06-24, it has been changed to 05-23 due to this change.
Finally, one more point needs to be explained. Airports with heavy air traffic load can have more than one runway. Some of these runways may be parallel to each other, in the same direction, or sometimes in different directions. For example ROME FIUMICINO AIRPORT.
You can examine the runways of some airports around the world in the figures below.
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