Airfield Markings and Signs

Airfield Markings and Signs

If you have ever looked at an airport from above — or even studied a satellite image — you will have noticed that the runways and taxiways are covered in painted markings. These are not decorative. Every line, number, and symbol has a precise meaning defined by international standards (primarily ICAO Annex 14). Pilots and vehicle drivers on the airfield rely on them constantly, especially at night or in poor visibility.

This lesson explains the main markings and signs you will find at an airport like Prestwick.

---

Runway Markings

Runway markings are white. This is universal — if it is white, it is on a runway.

Runway Designation Numbers

At each end of the runway, large numbers are painted indicating the magnetic heading of the runway, rounded to the nearest 10 degrees and divided by 10. At Prestwick, the main runway is designated 12/30:

• Runway 12 faces approximately 120 degrees (roughly south-east)
• Runway 30 faces approximately 300 degrees (roughly north-west)

The secondary runway is 02/20:

• Runway 02 faces approximately 020 degrees (roughly north-north-east)
• Runway 20 faces approximately 200 degrees (roughly south-south-west)

These numbers change very occasionally as the Earth's magnetic field shifts. Prestwick's main runway was historically known as 13/31 before being redesignated to 12/30.

Threshold Markings

The threshold is the beginning of the portion of runway available for landing. It is marked by a series of bold white stripes (like piano keys) running across the runway width. The number of stripes indicates the runway width:

Prestwick's Runway 12/30 is 46 metres wide, so you would see 12 threshold stripes at each end.

Centreline

A dashed white line runs down the exact centre of the runway. These dashes are typically 30 metres long with 20-metre gaps on a precision approach runway. Pilots use this line to keep the aircraft aligned during takeoff and landing.

Touchdown Zone Markings

These are pairs of rectangular blocks painted either side of the centreline, starting 300 metres from the threshold. They give pilots a visual reference for where they should be touching down. Not all runways have them — they are required for precision approach runways.

Aiming Point

Two large bold rectangles painted on either side of the centreline, typically about 300 metres from the threshold. This is where pilots aim during the final approach. Prestwick's Runway 12/30 has revised ICAO aiming point markings.

Displaced Threshold

Sometimes the landing threshold is not at the physical start of the runway surface. A displaced threshold is marked with arrows pointing towards the threshold. The paved area before the displaced threshold can be used for takeoff and roll-out, but not for landing. At Prestwick, Runway 12 has a displaced threshold of 243 metres.

---

Taxiway Markings

Taxiway markings are yellow. If it is yellow, you are on a taxiway or apron area.

Centreline

A continuous or dashed yellow line runs along the centre of each taxiway. Pilots follow this line — known as "keeping on the yellow brick road" in pilot slang. At Prestwick, the taxiways also have green LED centreline lights for use at night or in low visibility.

Edge Markings

Double yellow lines mark the edges of the taxiway where there is pavement beyond the edge (such as an adjacent apron). A single yellow line is used where the taxiway edge meets unpaved ground.

Runway Holding Position

This is one of the most critical markings on the airfield. It consists of two solid yellow lines and two dashed yellow lines running across the taxiway, perpendicular to the centreline. This marks the boundary that an aircraft must not cross without ATC clearance.

At Prestwick, holding positions are located at points designated J (Juliett), K (Kilo), Q (Quebec), R1 (Romeo One), S (Sierra), W (Whiskey), and Y (Yankee). Several of these have LED stop bars that illuminate red when the hold is active.

The rule is simple: solid lines on your side means stop and hold. You need clearance to cross them.

Intermediate Holding Position

A single dashed yellow line across a taxiway indicates a point where ATC may instruct an aircraft to hold, but it does not require automatic stopping like a runway holding position.

---

Airfield Signs

Airfield signs follow a colour-coding system that is consistent worldwide:

Mandatory Instruction Signs (Red Background)

These have white text on a red background and MUST be obeyed. They include:

• Runway designation signs — e.g., "12-30" at a holding point, telling you that crossing this sign puts you on the runway
• NO ENTRY signs — red circle with white horizontal bar
• Category I/II/III holding point signs — marking ILS-sensitive areas

You will never ignore a red sign.

Location Signs (Yellow Text, Black Background)

These tell you where you are. A black sign with yellow text and a yellow border identifies the taxiway you are currently on — for example, "J" for Taxiway Juliett.

Direction Signs (Black Text, Yellow Background)

These tell you where you can go. A yellow sign with black text and an arrow points towards other taxiways or the runway — for example, "R" with an arrow pointing left means Taxiway Romeo is to your left.

Information Signs (Black Text, Yellow Background, No Border)

These provide supplementary information such as noise abatement areas, radio frequencies, or specific procedures.

---

Runway Guard Lights

In addition to painted markings and signs, many holding points are equipped with runway guard lights. These are flashing yellow lights (either elevated lights either side of the taxiway, or in-pavement lights across the taxiway) that warn pilots they are approaching a runway. At Prestwick, several holding points have LED runway guard lights.

---

Quick Reference

---

Try It Yourself

Next time you look at satellite imagery of Prestwick (or any airport), see if you can identify:

1. The runway numbers at each end of 12/30

2. The threshold stripes

3. The displaced threshold on Runway 12

4. The taxiway centrelines in yellow

5. The holding position markings where taxiways meet the runway

Understanding these markings gives you a whole new appreciation for what pilots see when they look out of the cockpit window.