Just as you have street signs and painted lines on the roadways to help you whilst driving, airports have painted markings and signs to provide information, aid operations, and identify the various runways, taxiways, and ramps. Each runway is identified with large white numbers painted on each end. These numbers may seem arbitrary, but in fact, they correspond with the magnetic direction they face.

These become the runway's name. For example, a runway laid out east west would have a 9 painted on one end of the runway, and a 27 painted on the other end. These numbers denote the magnetic headings of 90 degrees and 270 degrees that an airplane would be flying when taking off. or landing on that runway.

When labeling the runways, the magnetic heading of the runway is rounded off to the nearest 10 degrees, and the last digit and any preceding zeros are dropped. For example, a runway with a magnetic heading of 068 degrees becomes Runway 7. Additionally, the runway name is pronounced with each digit separately.

For example, Runway 27 is actually called Runway 27. Sometimes, however, one or more other runway markings may also be oriented to the same heading. So, to differentiate between the runways, the suffix is left. Center and right are also used. Two parallel seven runways would be labeled as seven left and seven right.

If there are more than three parallel runways, some of the runways would be assigned a different number. Dashed center stripes are painted on runways to aid pilots with alignment when taking off and landing. The most basic of runways will only include the numbers and center line stripes. However, more sophisticated runways will have additional markings.

These markings can identify the runway edges, the threshold, the touchdown zone, and the pilot's aiming point. Finally, additional stripes are used as distance markers each 500 feet. Not all runways are usable. To mark runways that are undergoing maintenance, are currently unsafe, or have been permanently closed, yellow X's are placed on the ends.

These markings can be painted on the runway or may be temporary structures. Additional X's may also be placed at intervals along the rest of the runway. Runway markings are also used to indicate when certain portions of a runway are not usable for takeoff or landing. If part of the approach end of a runway is usable for taxi and takeoff but not landing, it will be labeled as a displaced threshold and marked with white arrows.

Landing on this portion of the runway is not permitted because terrain or man made obstructions require an airplane's approach path to be relocated farther down the runway to provide adequate clearance. You can, however, use this portion of the runway to slow the aircraft to a stop after touching down during a landing, but only when that landing is from the opposite end of the runway.

Runway pavement that cannot be used for taxi, takeoff, or landing is marked with yellow chevrons. This area can only be used for emergency overrun or has been placed there to limit ground erosion from jet blast. To travel between the runways and the parking ramps, most airports have taxiways. Since runways are labeled with numbers, taxiways are given letter designators.

Also, while painted runway markings are white, taxiway markings are yellow. At larger airports, taxiways will have a solid yellow stripe to mark the center of the taxiway, and solid double yellow lines to mark the edge of the taxiways. When a taxiway comes in contact with a runway, runway holding position markings are used.

These markings identify where an aircraft is supposed to stop when approaching a runway. They consist of four yellow lines, two solid and two dashed, extending across the width of the taxiway. The solid lines are always on the side where the aircraft is supposed to hold. This means that the solid lines are on the taxiway side and the dashed lines are on the runway side.

When approaching these markings, if you are on the side with solid lines, you must have permission to cross the boundary. If you are instead on the side with the dashed lines, no permission is needed to cross. To coincide with these hold lines, larger airports may additionally use an enhanced taxiway centerline.

This enhanced taxiway centerline consists of a parallel dashed line painted on both sides of the centerline and is used up to 150 feet prior to a runway. This warns the pilot that they are approaching a runway holding position marking and may need to stop. If an aircraft is trying to land at an airport during inclement weather where fog or clouds are preventing a pilot from being able to land visually, that pilot can potentially utilize that airport's instrument landing system or ILS.

Assuming the airport has one, and the pilot is qualified to use it. In simplified terms, this system transmits radio waves from stations on the airport up to the aircraft and guides the pilot down to the runway. An aircraft taxiing on the ground can potentially block these radio waves and prevent the approaching aircraft from successfully landing.

Because of that, additional holding areas may also exist to denote these ILS critical areas and prevent any stationary aircraft from blocking the signal. Holding markings for ILS critical areas consist of two parallel lines stretching the width of the taxiway connected together with pairs of perpendicular lines.

The marking resembles that of a ladder. Please note, you do not have to hold short of this marking unless specifically instructed by ETC to do so. Airport parking areas are called ramps. They are also known as non movement areas. A curious designation, since you're allowed to move about on these ramps without ATC permission.

However, this name actually makes sense, because the taxiways and runways are considered movement areas, where permission is necessary to move about. The border between ramps and taxiways is marked with yellow stripes. A single solid line on the ramp side and a single dashed line on the taxiway side.

Just like with runway hold lines, permission is required to cross the line when on the solid side, but not when on the dashed side. The final markings we'll discuss are lead in and lead off lines. These lines are painted on the runway to guide aircraft onto and off of the runway.

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