Have you ever looked out of the plane window and wondered what all those wonderful colored lines, signs, and lights actually mean? Then you've come to the right place. Here's is our short guide to what all those signs are saying.

If you want to know more, the FAA is the central authority for most international airports. You can also read Kate Ascher's The Way to Go.

The Lines

Unless you spend your time immersed in a good novel or reading a paper during flights, or if, like me, you like to predict the moment when the plane's wheels touch Mother Earth, you might expect the pilot to come down on the nearest patch of asphalt/concrete possible on landing. This is definitely not the case; there is an entire lexicon of lines and indicators that pilots must obey on landing and takeoff. Most international airports follow the same patterns, defined by the FAA's advisories on runway markings.

First up is the "Blast Pad". How much money was spent coming up with this term, I wonder? Who cares? It's awesome!

You may not necessarily notice this area of the runway as a passenger, but it's the yellow-chevroned section at the start of the runway. As the name suggest, this area is intended to absorb or resist the exhaust "blast" or "jet wash" from the jet engines without compromising the main section of the runway or surrounding earth, objects and people. In fact, this area of the runway is not designed to take the weight of an aircraft at all.

The runway proper begins with the "Threshold." This is just what it sounds like: a number of thin, long lines that are used to indicate the width of the runway.

Directly above the threshold area you will find a number, sometimes followed by a letter. These, according to the FAA, denote the runway name and correspond to the "the nearest one-tenth magnetic azimuthal centreline of the runway". Given that there are 360 azimuthal degrees, runway numbers will only ever go up to 36. The letter enables the airport in question to discriminate between two parallel runways, if present. The dashed line is called the center-line for obvious reasons and, again, acts as a visual aid for the pilots like road markings do for car drivers.

So far so good, but none of the above are actually intended to be landed on (indeed, landing on the blast pad, in particular, might be catastrophic).

To those of us who are not trained pilots, the "touchdown" section of the runway is inconspicuous. From the above image, you will notice the six vertical lines after the runway number. These provide an unambiguous visual aid to pilots during landing.

The more observant reader might ask, "What about the thicker rectangular markings on runways?".

Those are actually visual aids for pilots. They' are called the "aiming points," and they're what the pilots are supposed to be looking at when coming in for a landing.



The Numbers, Colors, and Signs

The font or typeface of signs is also regulated by the FAA. For example, its guidelines include provisions for the number "1" having a horizontal tip to avoid confusion. All text must be 60 feet high, except the numbers "6" and "9" because of their "tails".

When removing obsolete characters the airport must sandblast them away, not paint over them. This is to prevent the new marking decaying and revealing the old information. That explains the light-colored spots or words you might see on the runway.

Have you ever noticed those red signs dotted around? These act like Stop signs for the pilots. The FAA says that these are the "holding positions" for an aircraft while it's taxiing or waiting to take-off. The numbers are there to help the air traffic controller coordinate the comings and goings.

When a pilot reaches a short line at a runway entrance the red block denotes which runway the pilot is about to enter. For example, "18-36" indicates that Runway 18 runs from left to right and Runway 36 runs from right to left.

Black signs with a number tell the pilot how many thousands of feet are left on the runway, which is useful to know even in imperial units. Anything painted white is reserved for the actual runway itself while yellow is all about taxiing or, in some cases, designates no-go zones.

Gates are identified with yellow numbers and markings when the aircraft gets closer to the terminal building.

[Image Source:Gizmodo / Kate Ascher]

The Lights

The FAA not only assigns standards to paint and signs but the lighting too.

Depending on where you sit as a passenger and the kind of plane you're traveling in, you may not appreciate the myriad of lights that pilots must obey. Generally, you'll most likely see blue lights. These indicate the taxiway edges or, if they are white, will indicate the touchdown area of the runway.

According to the FAA, green lights designate the threshold, where the actual runway starts, while red always means exactly what you think it means: do not go!

You may also notice white lights when approaching a runway. These form distinctive short lines of light that begin long before the runway. They are very powerful and important lights for pilots and are called approach lights.

After the approach lights, there is a further wider line of light that directly precedes the runway. This provides an aide for pilots at a critical phase in landing. At the point that the pilot transitions from using the cockpit instruments to their own eyes, they need to take their eyes of the attitude indicator. If the weather is inclement or dark, it is possible that the pilot might have trouble identifying the lateral bank cues necessary to keep the aircraft straight and level. This decision bar performs the duty of an external attitude indicator providing the pilot with a visual aide on landing.

LED controversy

There has been an increase in the use of LEDs on taxiways and runways across the globe. Clearly, this makes an enormous difference to the airport's bottom line but are they safer than incandescent lighting? Some American pilots complain that they are blinding or distracting during takeoff and landing.

"I've heard that, but I don't agree," says commercial pilot Chris Manno in an article on Gizmodo. "It can be a little bit of an annoyance, but it doesn't cause a problem, and in fact, I think they're an improvement over the old lights," Manno says that the lights are brighter in foggy conditions, and they make it much easier to find the runway. "We're starting to convert the aircraft landing and taxi lights because it's so much better,"

So there you have it; your plane journeys will never be the same again. Now you can show off to your loved ones what all those colorful signs, markings and lights mean.

Taxiway Addendum

A picture (well video) speaks a thousand words...

The following video provides a great summary of the signs, markings, and lighting of taxiways:

Sources: Gizmodo, FAA