What Do Airport Runway Markings Mean?
Airports have their very own language when it comes to runway markings. And although millions of people fly all over the world every day, with Heathrow transporting 206,800 people on average every day last year, it is very likely that most people completely overlook the markings that are critical in ensuring their safety.
If this blog were to go into detail about every single runway marking, it would go on for years, as there are so many different forms and reasons for different markings, from designated zones for air crafts even down to the usual walkways. You can view some of these in Meon's Case Study for Dublin Airport.
Most airports around the world follow the same pattern when it comes to their runway markings, using symbols and different lines for the pilot to be able to safely take off and land the plane. Below are listed the main markings:
The Blast Pad
At the very beginning of most runways, you will find a 'blast pad'. This is a patch of what looks like the runway, although it is normally not strong enough to hold the weight of a plane, meaning landing on it would cause a 'catastrophic error', and cause a lot of damage costs to both the surface and the plane. This is usually painted with yellow chevrons and is designed to prevent the 'blast' of departing jets from doing any damage to the surface found just before the runway.
A short while after the blast pad is where you will find the threshold. As the name indicates, this marks the start of the 'real' runway. The threshold is marked by a number of long and thin white runway markings, which the Pilot uses to indicate the width of the runway with.
Number of Stripes
Numbers and Letters
If you look at the image below, you will see the letter 'L' followed by the number '26'. Unlike the numbers, the letter you find on the runway (if there is one) is there for a very simple reason; If there are 2 or 3 runways parallel to each other, the letters simply define whether it is the right, left, or centre runway ('R','C','L').
The number is slightly more mathematical to work out. It is determined by the 'nearest one-tenth the magnetic azimuth of the centreline of the runway'. Or in a simpler form, the compass bearings of said runway.
For example, a runway that is 214° from the magnetic north would first be rounded to the nearest ten: 210°. Then the last digit (the zero) is dropped, leaving us with 21. Now if the runway is being used for both directions, the number facing the opposite way would be 21-18 (210°-180°) = 3.
As the Pilot will be looking out for these markings when approaching the airport from the sky to land, they need to be specifically designed so that it is almost impossible to confuse one with the other. The also need to be the right width and height to be visible. Because of this, runway markings actually has its very own font. Each character must be perfectly marked out in accordance with the designed font, and be exactly 60 feet high, except 6 and 9—which can be 3 feet higher because of the tails. Everything down to the slant at the top of the number 1 has been engineered to give Pilots the clearest view of the runway's identity.
Further on from the numbers and letters marked out are the runway markings that the plane actually lands on. These are simply six short white lines parallel to each other. A little bit further up from these, you will find two large white rectangles. This is actually what the pilot aims for when landing, explaining their significantly higher visibility compared to the markings the plane lands on. Runway markings achieve high visibility through the use of high solids paints.
You can find out more about the range of paints airports use here
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