A passenger sitting in an airport landing at night could think that airport lighting system located there is just to enhance visibility.
Definitely, they would be right but only to a small extent.
Airport ground lighting is primarily responsible for navigating a pilot — the color, intensity and beam shape are important.
Thanks to the lighting systems used at an airport, a pilot controlling an aircraft can determine not only the moment to start landing but also the runway ending point, runway width and the location of collision-threatening obstructions.
Take a closer look!
Beacon is a lantern that enables identification of an airport from the air. It gives out a strong beam of flashing, white and green light. The flashes are visible from all directions — so a pilot can easily determine an approximate location of an airport. The lantern makes 6 spins in a minute.
Airport runway lights
An airstrip is often confused with a runway lighting system. In truth, a runway is a part of an airstrip used by airplanes to take off and land. An airstrip is an aircraft landing field and all the surrounding facilities that enhance safety. Runway lights consist of edge lighting, threshold lighting, centerline lighting and runway end identifier light and touchdown area lighting.
Let’s take a closer look at them…
Runway edge lighting
Runway edges are marked with white lights. They are installed no further than 3 meters from a runway edge at various intervals, depending on a runway type. At instrument runways, they are set at 60-meter intervals. When it comes to non-instrument runways, the intervals are 100 meters.
Edge lights are installed symmetrically with the runway centerline. Stopway lights are also installed on the edges — they give out a red, one-direction light. Sometimes, there is a need for an adjusted threshold — in the case of a damaged pavement, for instance. In that case, lights put before a runway threshold will have the red color from the approach point of view. At some runways, they are installed at 1/3 of a runway length but no further than 600 meters. They give out a yellow light.
Runway threshold lighting
A runway threshold is marked with two flashing lights placed symmetrically on both sided of a runway. They indicate a place that landing and taking off operation should take place under normal conditions. If there is an adjusted threshold, it is marked with white arrows that point the runway initial threshold.
Runway end identifier lights
Runway end identifier lights (REILs) are installed at runways equipped with edge lighting. These lights give out a red light from the approach point of view and green from the opposite direction. The lighting consists of at least 6 lamps place between the edge lights. They can also be set symmetrically with the runway centerline, in two groups. They indicate the runway end and simultaneously the beginning of a taxiway.
Runway centerline lights
Only some precision runways are equipped with runway centerline light. When it comes to precision runways CAT III, they are set at 15-meter intervals, from a threshold to another threshold, along the centerline. At other runways, the intervals are 30 meters. RCLs are two-directional. 900 meters from the runway end, white lights turn red-white, 300 meters from the runway end — red. High-intensity lights are used to illuminate a runway centerline.
Touchdown zone lights
Touchdown zone lights (TDZL) are used at precision approach runway CAT II and III. They allow for touchdown zone identification, both in low-visibility conditions and at night. Such lighting consists of bar lights that give out a white light. They are placed along the runway centerline, 30 meters from a threshold till the middle of a runway or 900 meters (it depends on which distance is shorter. They are installed at 30 or 60-meter intervals.
For some pilots, navigating an aircraft on the ground is more challenging than high up in the sky. An aircraft is not meant for that after all. Taxiways must be marked properly for an aircraft to navigate safely. Apart from taxiways leading from a runway to hangars, terminals and other airport facilities, there are also special-purpose taxiways: an aircraft stand taxiline, apron taxiway and rapid exit taxiway.
Approach lighting system
Approach lighting systems inform a pilot about his or her current location in relation to the approach path. They provide for safe landing operations. Currently, VASI and PAPI are the two most-often used systems.
VASI (Visual approach slope indicator)
VASI (Visual approach slope indicator) is to be found 7 meters from a runway initial threshold. It consists of two groups of lights put symmetrically on both sides of a runway. How does the system work? Although it seems that it should “detect” an aircraft altitude, in reality, the way it works is much simpler. The light color a pilot sees refers to the altitude an aircraft is on. Four white lights mean that it’s too high. The “in-the-approach-slope” position is indicated by two white and two red lights. Four red lights mean that an aircraft is too low.
PAPI (Precision approach path indication)
PAPI lights usually consist of four units placed on a runway, about 300 meters behind a threshold. They are visible from 4 km during the day and even 30 km at night. How does the system inform a pilot about the aircraft location regarding the approach path? Two red lights and two white lights mean that the aircraft is in the approach path. Three white — the aircraft is a bit too high. Four white — the aircraft is much too high. Three red — the aircraft is a bit too low. Four red — much too low.
Obstruction lights are used not only to mark high buildings and construction at an airport or in its surrounding. It can also warn about facilities located far away from an airport and are high enough to cause a collision threat. Lights of different intensity are used to mark obstructions, they are also divided into three types: A, B, C. Low-intensity lights mark obstructions that are not higher than 45 meters. Medium-intensity lights are used to mark vast objects and these that are higher than 45 meters. High-intensity lights can replace painted markings. Type-A lights are white, Type-B are red, flashing lights, Type-C lights give out a red, constant light.
Portable airport lights
Portable lighting is used in the events of occasional flights and maintenance or fixing operations of the airport main lighting. It can be also used as a temporary runway lighting. Their greatest advantages are obviously mobility and being easy to install and remove.
Airport solar lighting
It is clear now that airport lighting provides a lot of information which enhances safety. That’s why, as you can imagine, it must be reliable. A conventional lighting system works out well but solar lighting is gaining in popularity. In the past, it was used as an additional backup plan but the current systems are so advanced that a lot of airports use it as a permanent solution. This lighting alternative brings a great many advantages: it does not require an expensive and complicated power grid; it is cheaper, eco-friendly, easy to install and –most importantly — reliable.