The next time you go flying, no matter if you’re seated in business class, economy class or stuck in the very last seats in the back of the plane, look out the window and pay particular attention to those giant numbers that are at both ends of the airport runways.
Have you ever wondered why every runway at every airport in the U.S. (and just about anywhere else in the world), has them? What do they mean? What are their significance? And are they more than just a random set of numbers?
For the average clueless and/or scared-out-their-mind first time passenger, they might not mean much at all. But for the pilot, it’s a secret language used to safely operate the airline through traffic directed towards all the different runways.
The numbers signify it’s name. That turns out to be an essential component in helping pilots determine which runways are to be used for both landing and takeoffs. This is especially crucial when there are more than two parallel runways at some of the larger and busier airports across the country.
The size dimensions of these runway numbers, which have been tested, tweaked and carefully designed by the FAA, must be 60 feet high, except for the numbers 6 and 9 which can be three feet higher due to the tails.
Another thing to understand is how they are numbered. Every runway is numbered between 01 and 36. Each number matches a compass direction that is determined by the angle of the arc on the horizon between the direction of the centerline of the runway and the magnetic north.
An easy way to understand this is that 360° means north, 90° means east, 180° means south and 270° means west.
The difference between the two numbers is always 18. The initial number uses the actual compass direction rounded to the nearest 10 degrees and the last number is always dropped. The other number at the opposite end of the runway is 180° difference from one another.
For the non-gifted, ‘runway’ math-challenged individuals…
If you use the example of Runway 16/34, one hundred sixty degrees would be sixteen and pronounced as one six. (160° = 16). The number at the other end of the runway is the opposite number on the compass and that would be three hundred forty degrees or thirty-four and pronounced three four. (340° = 34). The difference between 340° and 160° is 180° or put another way, 34 minus 16 equals 18.
The optimal way for an aircraft to takeoff and land is to take advantage of the prevailing winds in order to provide both lift and resistance. Since wind conditions change from time to time, aircraft can use either direction when necessary.
If you’re starting to think that you’re feeling mighty fortunate that the air-sickness bag is within arms length, let’s throw out some more numbers to mess with your brain.
Sometimes the magnetic north shifts over time. It has been estimated that in the last 150 years, the magnetic north pole has strayed a total of 685 miles. If the shift becomes too extreme, the runway numbers will have to be changed. (That means more math!!!)
If you’re not confused already, here’s something else to think about.
There will be times when you land or takeoff at larger airports with more than three runways parallel to each other. When that happens, all three will have the same heading and you’ll see the letter ‘L’, ‘C’ or ‘R’ accompanied along with a numbered runway signifying Left, Center or Right.
As you make you way to and from your next destination, one of the things you might want to carry with you is the knowledge that you’ve gained and the information that you’ve learned. With these gathered facts now securely embedded in your brain, this funny, silly, useless trivia won’t get you a free ticket to wherever you want to go. But it might allow you to get some sleep on the next Red-eye.
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