The Meaning of Airport Runway Lights

Airports · 4 min read · Sep 14, 2021
Runway Lights

Nowadays, it is impossible to imagine a modern airport without one of its most notable attributes: the runway lights. Most of the passengers who are completely unrelated to aviation often speculate about the purpose of these lights. Yet, it is obvious that such a purpose is related to air traffic control. As well as that the runway lights are an indispensable help for anyone in charge of an aircraft in low visibility conditions.

Every light is a part of a sophisticated runway lighting system

Runway lighting is one of the most crucial parts of the whole airport lighting structure, so it must be fully operational at all times and fully compatible with The International Civil Aviation Organization standards. Virtually every one such system you’ll see during your travels will be not much different from any other operating at the most commercial airports in the world exactly because of the fact that it should be ICAO compliant. It is also not difficult to notice that there are different types of such airport lighting system elements.

Every one of them, runway edge/centerline lights, is designated to provide the pilot controlling the plane with crucial navigational information. 

This time, we will explain how airport runway lights are helping to take off or land the aircraft safely. We are also about to tell you everything you would want to know about different elements of the runway lighting system – and what every kind of runway light means.

Approach lighting system in a field next to a runway at Jyväskylä Airport.
Image source: https://en.wikipedia.org/wiki/Approach_lighting_system

In practice, there are nine main types, namely:

  • Approach Lights
  • Threshold Lights
  • Threshold End Lights
  • The lights of Runway End Identification
  • Runway Edge Lights
  • Runway End Light
  • PAPI Lights
  • Taxiway Lights
  • Obstruction Aviation Lights

Each of them has its own meaning, function, and color. Let’s overview them in more detail.

What are approach lights?

The first lights for anyone controlling the aircraft to notice when landing are the ones located directly prior to the runway. They are called ‘approach lights’ as they form an approach lighting system and are designated to show in which direction the runway begins. If you are about to land at one of the world’s biggest airports, the chances are that besides runway centerline lighting, you will notice the approach lights of different colors – namely, red, white, and yellow lights. However, at smaller airports, simple systems of about 15 to 17 white approach lights are installed.

The approach lighting system at Bremen Airport.
Image source: https://en.wikipedia.org/wiki/File:Approach_Lighting_System_Bremen_1.jpg

What color are airport threshold lights?

Green is the color for the runway threshold lights, which function as touchdown zone lights. Such signals of unidirectional type are usually put at the beginning of the part of a runway landing threshold where touchdown of the plane can be done as steady burning white lights. Completely another lighting system, on its part, is called Threshold End Lights. Such signals are red and green lights, going in two directions that indicate runway beginning and its end simultaneously. Therefore, if a plane would take the runway in its end direction, anyone in the cockpit could see that the runway emits red light.

What does REIL stand for?

REIL is the abbreviation for The lights of Runway End Identification. For common navigational purposes, such lights are not only extremely clearly visible in the landing threshold – and are designated to be promptly recognizable. In contrast to centerline lights, such lights are placed at the corners of the runway landing threshold in the direction of the area of the approach.

So what do Runway Edge Lights look like?

Runway Edge Lights, which outline the inner borders of the runway as the safe area for aircraft landing and takeoff procedures, are usually marked with pulsing white lights installed. On instrument runways, outside the safest area for landing, usually half the runway length, runway edge light becomes not white but yellow.

A landing aircraft and illuminated runway edge lights.
Image source: https://en.wikipedia.org/wiki/Runway_edge_lights

It is also worth noting that such systems are divided into:

  • High-Intensity Runway Lights (HIRL);
  • Medium Intensity Runway Lights (MIRL);
  • Low-Intensity Runway Lights (LIRL).

The first two tend to have variable intensity controls, but the light system of the last type usually has just one, just as runway centerline lights.

How can you distinguish a Runway End Light?

The runway End Light is always a red one as it marks the area where no runway can continue. So the Runway End Light is put at the end of each runway. However, in some airports, the runway end and threshold are in the same place, so bidirectional lights are usually installed there. The red lights are pointed in one direction, while the green lights are pointed in the opposite direction to emit green outward, similar to lead-off lights.

A central view of runway end identifier lights.
Image source: https://en.wikipedia.org/wiki/Runway_end_identifier_lights

PAPI lights are used as Precision Approach Path Indicator

Four lighting units, each of which can produce either white or red light signals, are the type of airfield lights, usually located on the left side of the runway. They help the pilot approach the ground correctly by choosing normal glide path angles – if two lights are white and two are red, the plane is approaching at the right angle.

A central view of a runway 27 with a precision approach path indicator (PAPI) light system located on the right
Image source: https://en.wikipedia.org/wiki/Precision_approach_path_indicator

Three red lights mean that the plane is slightly too low for an approach, while three red lights indicate that the aircraft is way too low. And vice versa – if all four lights are white, a plane is way above the designated glide slope.

So how can you spot the Taxiway Lights?

On taxiways and aprons, you can easily see a row of blue lights. Such lights are designated to help the pilot when moving off the main runway threshold, for example, while approaching the terminal building at night or in low visibility conditions. Taxiway edge lights are not easy to spot if you are just a passenger on the plane. However, the distinct blue color of such light systems will help you distinguish them when your plane has already reached the taxiway.

What is the purpose of Obstruction Aviation Lights?

Obstruction Aviation lights are lights marking any obstructions which may occur in the path of a moving aircraft. Such systems of omnidirectional lights – not to be confused with transverse light bars or centerline lights which can sometimes also be found here – are installed near the airport buildings or closed areas.

And that’s all?

Here we reviewed nine types of runway lighting systems used at virtually any commercial airport in the world. Some regional airfields may lack one or another type of such equipment, or let’s say, just another one centerline light position. At the same time, the biggest airports in the world will usually have more sophisticated lighting systems installed.

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Eglė Bartaševičiūtė
A passionate traveler and an avid aviation enthusiast bringing you the most well-founded, accurate and up-to-date industry content.

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