• How Things Work

The Annotated Airport

A guide to the meaning of the myriad signs, lines, circles, arrows, numbers, letters, and lights on the airport grounds.

• By Patricia Trenner
• Air & Space Magazine, March 01, 2005

AS AN AIRLINER MAKES ITS WAY AROUND an airport from the terminal to takeoff and, after the flight, back to the terminal, it encounters cryptic messages at every turn. To passengers, they may as well be hieroglyphs, but pilots understand them well, having been required to learn a second language: Airportese.

Airport Grounds

A rotating beacon, intended to be seen from the air, that flashes white and green, says, “This is a civil airport.” One green and two white flashes means ”military airport”—no civil aircraft allowed. White and yellow signifies “water airport”—floatplanes and flying boats only. Green, yellow, and white indicates “heliport”—rotary-wing aircraft only.

H Helicopter landing area

The elevation notice tells pilots this airport is, for example, 1,050 feet above mean sea level. The pilots make sure their altimeters agree.

A crew can taxi to the compass rose, align with a spoke, or bearing — 90 degrees, for instance— and check to see if the compass reads 90. (If it doesn’t, the compass needs to be recalibrated.)

The wind sock is a fabric or plastic cone that shows which way the wind is blowing. Aircraft take off and land into the wind. Taking off or landing with a tailwind increases the amount of runway required to lift off or come to a stop.

Lights

Blue lights outline a taxiway. Green lights run down the center.

White and yellow lights outline a runway. White lights run down the center.

Runway end identifier lights, a pair of synchronized flashing lights on each side of a runway threshold, indicate the approach end of a runway.

Stop bar lights are the row of red lights at a holding position where a taxiway meets a runway. When they go dark, accompanied by clearance from ground control, an aircraft may enter the runway.

Taxiways

Noise Abatement 2200—0700 LCL Follow noise abatement procedures between 10:00 p.m. and 7:00 a.m. This may require the pilot to maintain a best-angle-of-climb attitude after takeoff (which puts the aircraft at the highest altitude in the shortest horizontal distance), or a best-rate-of-climb (a gain of the greatest altitude in the least time); in other cases, it may require a takeoff at less-than-maximum power, or refraining from applying full power until the aircraft is, say, 10 miles from the airport. Noise abatement procedures lower the decibel levels for the surrounding community.

Taxiway ends.

MIL/TERM/CARG/RAMP Military, terminal, or cargo ramp (an aircraft parking area, also called an apron) facility is this way.

T This is a taxiway.

HS-1 Hold short (do not move until ground control tells you to) of the runway here.

Taxiway Alpha (A) A location sign, which tells you the taxiway or runway you are currently on, has yellow letters on a black square, the opposite of destination and direction signs. Here, Taxiway Alpha continues, angled to the right. Taxiway Charlie (C) runs to the left and right.

ILS Instrument Landing System critical area holding position. When instrument flight rules are in effect, ground control may hold an aircraft at this sign so it does not interfere with ILS signals.

Runwayholding position Stop here and do not move until ground control clears the aircraft to enter or cross the runway.

IF A CREW IS HOPELESSLY LOST, it might employ the bluff used in what is probably an aeronautical urban legend. Back when New York’s Kennedy airport was called Idlewild, a couple of neophyte pilots in a light aircraft requested taxi instructions for takeoff. Ground control responded with a hideously complex series of instructions involving turns at what seemed like a couple of dozen intersections. The frequency was silent as the pilots looked at each other cross-eyed and fumbled for a response. Finally, the copilot’s voice rang out over the radio, “Aw, the heck with it. Tell him ‘Roger.’ “

A better solution would be to ask ground control for a “progressive taxi,” in which a controller will provide taxi instructions to the pilot at each intersection encountered at the airport.

Runways

This runway, with a compass heading of about 200 degrees, is the left (L) of two parallel runways. Each runway is numbered by its compass heading rounded off to the nearest 10 degrees, with the last digit dropped. A runway that heads due north, 360 degrees, is numbered 36. The opposite end, which heads due south, 180 degrees, is 18. (Because Earth’s magnetic field changes over time due to the flow of the planet’s molten iron core—in fact, the poles swap places on average every 200,000 years—runway numbers are changed as Earth’s magnetic north pole wanders and field lines change the magnetic variation locally. For example, in 1999, Ronald Reagan Washington National Airport’s runway 18-36 became 19-1.)

4,000 feet of runway remain.

You are on Runway 22. Remember, “black square, you’re there.”

Touchdown zone markings: Pilots should try to put the main landing gear on the runway here.

B Exit B (Bravo) off the runway is just ahead, on the left.

Aircraft may not enter this area.

4 arrowheads This runway is 100 feet wide
2 arrowheads less than 60 feet wide

Alternately:
4 threshold stripes This runway is 60 feet wide.
16 threshold stripes 200 feet wide.

High-Speed Exit markings After landing, follow the green lights to make a high-speed exit from the runway.

A series of yellow chevrons: The runway threshold is “displaced.” Land beyond here.

X on runway (or taxiway): Closed.

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