Airport Markings: Runways

Runways are identified by a series of numbers and letters so pilots and air traffic control can clearly dictate instructions and position reports in reference to a specific runway.

Runway numbers and letters are determined from the approach direction.

The runway number is the magnetic azimuth (magnetic direction, or heading) of the centerline of the runway, measured clockwise from magnetic north. To simplify the designation, the heading (in degrees) is rounded to the nearest tenth, and the last zero of the number is dropped. For example, if you are standing on a runway and facing due East, 090°, the numbers painted on the runway would be 09.

In the case where there are parallel runways, the numbers will be followed by letters to indicate the parallel runways' relationship to each other, left (L), right (R), or center (C).

Thresholds

The runway threshold is the beginning of the runway surface that is designated safe for landing. If the threshold is not at the beginning of the runway pavement, it is called a “displaced threshold.” You should never land on the approach side of a displaced threshold!

While landing on the approach end of a standard displaced threshold (shown above) is not permitted, aircraft taking off may use the area before the threshold for taxi/takeoff roll, and aircraft landing on the opposing runway may use this area as rollout after landing.

If no aircraft movement is permitted in the area behind the approach end of a threshold, the pavement will be marked with large yellow chevrons. This indicates that this pavement is unsafe for any aircraft activity. At the end of the chevrons and before the usable runway begins, there will be a yellow "demarcation bar" that indicates the point at which unusable pavement ends and usable pavement begins. Sometimes the demarcation bar directly abuts the threshold (picture below, left), and sometimes the demarcation bar will be followed by a displaced threshold (picture below, right). In the latter case, the pavement directly following the demarcation bar, and before the threshold, is safe for taxi, takeoff roll, and opposite direction rollout only; as always, landing on the approach side of a displaced threshold is Not Permitted!

So what's the point of the pavement with the chevrons on it, you may ask? The pavement on the approach side of a demarcation bar, marked with large yellow chevrons, is an area referred to as a blast pad, and at some commercial airports, it houses a construct called EMAS. Technically, EMAS stands for Engineered Materials Arresting Systems, but a handy trick for remembering what the heck it actually does is to remember that EMAS is Extremely Mushy Asphalt. EMAS is an area of pavement much too soft for aircraft to operate on safely, but instead acts as a safety measure for aircraft landing on the opposing runway. EMAS is specifically designed to crumble under the weight of commercial aircraft, resulting in increased drag and deceleration force on the landing gear of the heavy aircraft.

Runway Holding Lines

Runway holding lines (picture below) comprise two continuous and two dashed lines perpendicular to the taxiway centerline; the continuous lines are on the taxiway side, the dashed lines toward the runway. 

When approaching the runway, do not cross the continuous lines or allow any part of the airplane to project over them until cleared for takeoff or crossing, or at an uncontrolled field, until certain that it is safe to takeoff/cross the runway. After landing, you are not clear of the runway until all parts of the aircraft have crossed the holding lines.

Types of Runways and Associated Markings

Calm-wind Runway

For noise abatement reasons, an airport may designate a “calm-wind runway” that is recommended as the runway to use when the wind is less than 5 knots. 

If the field is controlled, the tower may assign a runway based on the noise abatement procedures in place at the airport. Remember, these procedures a recommendation, so if you wish to use a different runway, just ask. Most likely, the tower will honor your request if possible.

Note: The figures above detail how runways should be marked, keep in mind, however, that sometimes runways can be painted incorrectly. Ensure before every flight that you make note of available landing distance and quality of the runway at your destination.

When flying to a runway that has Non-Precision or Precision Markings, it is advantageous to use those markings as reference point for your approach to landing. Normally using the Visual Approach Slope Indicator (VASI) will guide you to the Aiming Markers 1000’ down the runway. The markings can also make achieving your practical test landing requirements easy if you focus on aiming at a point before your intended touchdown and then touch down in the area you have selected. 

In the example above, we intend to land in between the 1000’ Aiming Point Markers, so we select an aiming point before them. Depending on your aircraft and approach speed, you may need to adjust your aiming point. Aiming for a point before your intended touchdown point allows the aircraft to round out, flare and touch down on your specified point.

Permanent Closures

If a runway is permanently closed it will be permanently marked with large, painted, yellow "X's" at each end of the runway and along the length of the runway every 1,000'. The threshold, designation numbers, and any touchdown/aiming points will be obliterated, and runway lighting will be disconnected.