By Ian J. Twombly

Where are you?

Knowing signs and airport markings is the key to successful ground operations

Learning how to maneuver an airplane on the ground through the maze of an airport can indeed be difficult. But knowing how to do it safely is as important as knowing how to land or take off—perhaps even more so when you consider the potential consequences of a runway incursion. Mastering ground operations is as easy as knowing the signs, markings, and lighting, and remembering a few tips that will keep you safe.

Part of the difficulty of taxiing around an airport is that no two are the same. We can drive any highway in the country because the lanes are more or less a consistent width, and there are rules on how they’re built. But although our airports all look different, the signage, markings, and lighting are remarkably similar—generally even more than we’re used to in our ground-based lives.

Every aviation sign is in one of six distinct categories—mandatory, direction, location, destination, information, or runway distance remaining. Each category indicates both a purpose and a type of display.

Mandatory signs indicate things such as runway entrances where a clearance is required, and Do Not Enter signs for areas where aircraft aren’t allowed. These are red with white lettering. Direction signs are placed at intersections; they have a letter or number with an arrow indicating the direction of a runway or taxiway, and are yellow with black lettering.

Destination signs are similar in appearance to direction signs, except that multiple locations may be placed on one sign. If two runways are to the right, for example, they both will be listed with an arrow. And in general terms, the location that’s being referenced is farther away than an immediate intersection.

Location signs are black backgrounds with yellow lettering (the reverse of direction and destination signs), and indicate your current position. Typically they are found along a runway or taxiway. Information signs are also yellow with black lettering, and indicate things such as noise abatement procedures, radio frequencies, and other airport-specific information. Runway distance remaining signs—black with white lettering—show how many thousands of feet are remaining.

What makes signage so difficult is that there are often multiple signs in one intersection, or the intersection may be angled or irregular. Like major roadway intersections, large airport intersections can be difficult to interpret when there are a number of different taxiways converging.

Although they can be confusing, airport markings are fairly straightforward and highly standardized. Luckily, learning only the basic markings is quick and easy, but delving deep into the lesser-known markings can bring a wealth of information.

By now you probably know that taxiway markings are yellow and runway markings are white. Taxiways typically have two solid yellow lines on each side to denote the edge of the taxiway, and one yellow centerline to denote the middle. You might not be an expert at actually taxiing on that line, but at least you know what it means. That centerline, by the way, is between six inches and 12 inches wide, and does not ensure wingtip clearance at any time. Larger airports may also have enhanced centerline markings, which are a dashed line on either side of the centerline. They denote an approaching runway intersection.

That runway intersection is probably the most critical spot on the airport, and it is marked with a somewhat misunderstood pavement marking. The runway holding position marking, or hold short line, is a series of two solid and two dashed yellow lines. The solid lines will always face the taxiway, while the dashed side will always face the runway. That’s because a clearance is always required to cross the solid side, while one is never required for the dashed side (see “Hold Short Line" below). If you are familiar with only one light, sign, or marking on the airport, make it this one.

Once you cross onto the runway, things get a little more complicated. If it’s a runway without an associated instrument approach, it will most likely have a dashed centerline and the numbers. That’s it. While some may also have edge markings and a threshold, they’re not required. Runways with an associated instrument approach get more complicated, and although they are meant for pilots coming off an approach, many of the markings can help VFR pilots as well.

Runways with an associated nonprecision instrument approach add on a few things, such as the threshold marking and an aiming point. The threshold is just what it sounds like—the beginning of the landing area. This is helpful because it’s often easier to see farther out on final approach than the end of the pavement itself. The addition of an aiming point is even better. This is the spot in the windshield you should reference for a safe landing. Is it going up in the windshield? You’re too low. Is it going down? You’re too high. It’s much easier to reference this than a centerline stripe or a sign by the side of the runway.

Runways with a precision approach get even more complicated. Again, none of the markings is necessary for visual pilots, but knowing them will really help you. The two big additions are a touchdown zone and threshold stripes. Technically, the touchdown zone is for pilots flying an electronic glideslope. But if you’re using the aiming point, it’s also where you should end up landing. It’s a great reference for spot landing practice.

Threshold stripes, while seemingly useless, hold a fun and unique purpose. While some runways have eight uniform threshold stripes that do nothing but help delineate the threshold, others have a varying number of stripes to signify the runway width. There are four stripes on a 60-foot-wide runway, six stripes on a 75-foot-wide runway, eight stripes on a 100-foot-wide runway, 12 stripes on a 150-foot-wide runway, and 16 stripes on a 200-foot-wide runway. Suffice to say, even four stripes indicate that a runway is wide enough for a training airplane.

There are two other runway markings that are critical for pilots. Both indicate a displaced threshold, or area not available for landing. One is a series of yellow chevrons that indicates an area of pavement not available for taxi, takeoff, or landing. The other is a collection of white arrows prior to the threshold. That area is available for takeoff and taxi, but not landing. Typically the threshold will have moved because of an obstruction, which is why you can take off or taxi, while chevrons may indicate poor pavement—meaning the area is completely unusable.

Airport lighting is very straightforward, and can also be used to communicate many details that help in safe operations. The first thing a pilot will see is the airport beacon. These are alternating green and white (except for military airports and seaplane bases). They are most visible between one and 10 degrees above the horizon. Although you can expect to find a beacon on at night, they sometimes are illuminated during the day as well. If you see one on, check the weather report. Chances are you’ll find the airport is IFR.

Approaching the runway, you’ll often see a glideslope indicator in the form of a VASI (visual approach slope indicator) or PAPI (precision approach path indicator). Typically they will be set to a 3-degree glideslope, and be visible from three to five miles away during the day and up to 20 miles at night. Each system provides obstruction clearance, making it vital they be followed for night operations.

Runway lights are white—mostly. On runways with an instrument approach, the lights turn to yellow in the last 2,000 feet or half the length of the runway, whichever is less. And often the end lights will be red to keep pilots from going off the runway. Taxiway lights are blue, and taxiway centerline lights—if they’re present—are green. The pilot can turn on all those lights via radio with seven clicks of the mic button, or five for medium intensity, and three for low. In the vast majority of cases, pilot-controlled lighting is accomplished over the common traffic advisory frequency, but there are cases where a dedicated PCL frequency has been designated. They can be found in the Airport/Facility Directory. At an airport with an operating control tower, you can ask the controller to adjust intensity.

From lights to signs and markings, airports can be their own cities. Especially if you are learning to fly at a small or rural airport, take the time to venture to the big city with your instructor. The good news is that once you are comfortable at a big airport, you’ll find that the practical use of airport knowledge is scalable, and you’ll never worry about landing at even the largest Class B airports.