A passenger landing at night at an airport might think that the lights on it are simply used to improve visibility. And of course they would be partly right, but only to a small extent.
Airport ground lighting (AGL) is primarily intended to navigate the pilot. Each light provides the pilot with information necessary for safety – its color, intensity and beam shape are important.
Thanks to the light systems used at the airport, the person controlling the aircraft is able to determine not only the moment when they should start landing, but also where the runway ends and begins, its width, as well as – where there are obstacles that may cause a collision.
And so we distinguish the following airport navigation lights:
Beacon (anti – collision)
Beacon is a lighthouse that allows the identification of a given airport from the air. It emits a strong stream of flashing light in white and green. Flashes are visible from all sides – so the pilot can easily determine the approximate location of the airport. The lighthouse makes 6 revolutions per minute.
Runway lights
Runway lights consist of edge, threshold, central axis lighting, as well as runway end and touchdown lighting. Let’s take a closer look at them.
Runway edge lighting
The runway edges are marked by white lights. They are installed at a distance of not more than 3 meters from the edge of the runway at various intervals, depending on the type of road.
In the case of an instrument road, they are spaced 60 meters apart, whereas on a non-instrument road this distance is 100 meters. The edge lights are placed symmetrically about the runway axis. The interruption lights for the interruption of start are also mounted on the edges – they are unidirectional and red. Sometimes there is a need to shift the threshold – for example, in the event of damage to the surface of the airport runway. The edge lights of the sill will then be red from the approach side. On some runways, 1/3 of their length, but not more than 600 meters, is installed in yellow lights.
Runway threshold lighting
The runway threshold is marked with two flashing lights placed symmetrically on both sides of the runway. They indicate the place where take-offs and landings at a given airport should normally take place. If you are dealing with a shifted threshold, it is marked with white arrows pointing towards the initial runway threshold.
The airport’s navigation lighting also includes:
Runway end identifier lights
Runway end identifier lights (REILs) are mounted on runways with edge lights. These are lights that shine red from the runway side and green from the other side. This lighting is at least 6 lamps spaced between the edge lights. They can also be spaced symmetrically about the runway axis in two groups. They indicate the end of the runway and at the same time the beginning of the taxiway.
Runway centerline lights
Some precision runways are equipped with runway centerline lights (RCLs). For category III precision runways, they are positioned at 15 meter intervals, from threshold to threshold, along the center line. On other runways, these distances are 30 meters. RCLs are two-way lights. 900 meters from the end of the runway, white lights turn into white and red lights, and 300 meters from the end of the runway – into red lights. High intensity lights are used to illuminate the runway’s central axis.
Touch down zone lights
Touch down zone lights (TDZL) are used on runways with a precision approach of categories II and III. They allow the identification of the final approach zone, both in poor visibility and at night. This lighting is made of light bars that give a constant light in white. They are located along the runway center line, from 30 meters from the threshold to the center of the central road, or up to 900 meters (whichever is less). They are installed every 30 or 60 meters.
Taxiway lighting
Controlling an aircraft on land is more challenging for some pilots than controlling it in the air. After all, it is not intended for this. Airport taxiways must also be marked so that the aircraft moves safely along the designated route. In addition to the taxiways that mark the route from the runway to the hangars, terminals and other airport facilities, special purpose roads are also designated: platform road, rapid descent route and taxiway to the parking stand.
Approach lighting system
Approach lighting systems are designed to inform the pilot about his current position relative to the glide path. They ensure safe landing operations. Currently, the most common indicators are VASI and PAPI systems.
VASI (Visual approach slope indicator)
VASI is a visual system that indicates the glide path. We will find them at a distance of 7 meters from the threshold of the initial runway. It consists of two groups of lights placed symmetrically on both sides of the runway. How does such a system work? Although it might seem that it should “detect” the height of the aircraft, in reality its operation is much simpler. The color of the lights that the pilot of the landing plane sees depends on the height of the machine. Four white lights indicate that the plane is too high. The “on the path” position is indicated by two white and two red lights. Four red lights indicate that the plane is too low.
PAPI (Precision approach path indication)
PAPI lights are precise indicators of the approach path. They usually consist of four units located at the runway, about 300 meters on the threshold. They are visible from a distance of 4 kilometers during the day and up to 30 kilometers at night. How does the system inform the pilot about the position of the machine relative to the approach path? Two red and two white lights mean the aircraft is on the approach path. Three white – plane a bit too high. Four white – plane much too high. Three red – a bit too low. Four reds – far too low.
Obstruction lighting
Obstruction lighting is not only used for tall buildings and structures located at or near the airport. It can also warn about objects far away from the airport, but because of their height, posing a collision hazard. Lights of varying intensity are used to mark obstacles, and we divide them into three types: A, B and C. Low-intensity lights mean obstacles whose height does not exceed 45 meters. Medium intensity lights are used to mark bulky or tall objects that exceed 45 meters in height. However, high-intensity lights can replace the marking of obstacles in the form of painting. Type A lamps are white, type B lamps are flashing and red, while type C lamps emit red solid light.
Portable airport lights
Portable lighting is used for occasional flights and for maintenance or repair of main airport lighting. It can also be used as temporary runway lighting. Of course, their main advantage is mobility, as well as ease of installation and disassembly.
Airport solar lighting
As you can see, airport lighting provides a huge amount of information to strengthen security. Therefore, as you can guess, they must be reliable. Conventional lighting systems fulfill their role well, but solar lighting is becoming more and more popular. Earlier it was used as an additional protection, but now solar systems have been improved so that many airports can boast of constant lighting, to which energy is taken from the sun. This type of lighting has many benefits: it does not require building an expensive and complicated network, it is cheaper, ecological, and easy to install and – most importantly – reliable.
As a curiosity, we add that one of the innovators of the airport lighting market in the world is the SOLUTIONS4GA company with headquarters in Warsaw offering solar as well as portable airport lighting (more on this topic), helipad and obstacle lighting.
That’s all when it comes to airport lighting. We invite you to read other articles and tips on our website!