Aviation activities take place in many different places, environments, and situations, and that includes night operations and operations under low visibility conditions. Therefore, lighting becomes essential to guarantee aviation operations are carried out effectively and safely. Here is where taxiway lighting becomes relevant.
Are you ready to discover what taxiway lighting is and its purpose of it? Keep reading as we provide you with the details.
The lights on the taxiway are a group of lights that form the taxiway lighting systems. It is important to remember that the taxiway is different from the runway. While the runway is the area used for takeoff and landing, the taxiway provides access from the terminal and hangar areas to the runway and vice versa.
During the day and with good visibility conditions, the taxiway and the runway are well identified with signals that are easy to see and understand by the pilots of an aircraft. However, during the night or under low visibility conditions, these signals become useless, and the airport taxiway lighting systems take the role.
Following the previous point, it is clear that the main purpose is to ensure that the flight crew and vehicle drivers moving on the taxiway use the correct routes to reach their destination, especially for aircraft that adhere to ATC clearance limits.
In general, commercial airports are required to have lighting on their taxiway following the standards set by the International Civil Aviation Organization (ICAO). This is mainly to guarantee they meet the safety requirements for operation. However, there may be some exceptions.
There are different colors used for the taxiway lighting. The type of color used will depend on the area of the taxiway the lights are identifying. Among the different light colours used there are blue lights, red lights, as well as green and yellow lights.
There are several lights that form the taxiway system because there are different areas that require specific identification.
For example, for pilots to maneuver after landing or before takeoff under the conditions mentioned above, such areas like the runway exit, intersecting taxiways, and crossings between them must be clearly identified.
This said, let’s see some of the lights according to their specific purpose.
Similar to runway centerline lights, taxiway centerline lights are installed to identify the main taxiways. These are green lights located in the taxiway centreline, and sometimes on a runway exactly before a designated exit taxiway to provide guidance.
While these are generally green lights, they are sometimes used in alternation with yellow lights to identify an area of the taxiway designated as ILS-sensitive, or either crossing or too close to the runway that may generate an obstruction, indicating that no aircraft or vehicle should stop there unless obtaining explicit ATC approval.
These lights are installed in-pavement and are bidirectional to provide guidance to aircraft and vehicles in both directions.
These lights form a system normally called blue taxiway edge lighting. While green taxiway centerline lighting is used for the major taxiways, the blue edge lighting is applied to identify minor ones. However, they are frequently used in combination as a taxiway guidance system in areas with a higher difficulty for the pilots to maneuver.
While they have a constant spacing, usually around 60 meters (200 ft.), this spacing depends on the layout of the taxiway. For example, when there is a bend, the spacing is reduced to help the crew have a better view of the radius.
Taxiway centerline lighting has proved to be better guidance than blue edge lighting under low visibility circumstances, which is why the latter is left for minor taxiways.
Also called RGLs, the runway guard lights are also in-pavement lights, and they are used to identify the intersection of a taxiway with a runway. This way, pilots and vehicle drivers are warned about the fact that they may be entering an active runway.
Runway guard lights are normally located about 1 meter or 2 feet from the entrance to the active runway, and they go across the taxiway in a 3-meter (10-feet) spacing.
It is clear that taxiway intersections are critical areas during the night and in low visibility. While most airports use the taxiway centreline lighting and the full taxiway guidance system, there are some that still do not have it.
Therefore, they must use taxiway intersection lights that are a group of at least 3 steady yellow lights disposed symmetrically about the taxiway centerline to indicate that aircraft should give way to crossing traffic unless they receive specific clearance from ATC.
Stop bar lights are used on an airport taxiway when low visibility procedures (LVP) are set. Also known as lighted stop bars, the stop bar lights are evenly spaced lights placed from a taxiway edge to the other, usually forming right angles with the taxiway centreline and providing visual aids in red for an approaching aircraft.
As the name suggests, these lights are also used with additional elevated red lights to provide lead-off guidance towards the stop bar location, also working as a control system that signals the aircraft must stop, holding position on the taxiway, and it is not allowed to enter the runway environment until receiving specific clearance.
Clearly, this lighting system is used to provide a visual aid to identify critical areas of the taxiway, especially helping aircraft to move into the runway for takeoff or out of the runway after landing.
Taxiway lighting is designated as either high intensity or low intensity. Normally, specifications are given for high-intensity lighting to be used in low visibility conditions while low intensity is good enough for operating during the night.
Finally, taxiway centerline lighting, edge lighting, runway guard, and stop bar lights follow the ICAO standards, the truth is that using one group, or a combination of them lies on the sole discretion of an airport operator.
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