What are Runway Lights?

All functional airports have to be equipped with the best lighting system. The purpose of the airport lighting system is to guide the pilots during takeoff and landing at night or in low-visibility conditions. One of the most critical parts of the airport lighting system is the runway lights. Lights should be clearly visible, work continuously in all operating conditions, and be ICAO compliant. 

Flying an aircraft at night is challenging for pilots, especially while landing. In the daytime, it is easy for pilots to navigate the runway and avoid any obstacles. However, pilots rely on runway lighting after dark to help them safely land at the airport. Not having a solid understanding of runway lights can cause pilots to have severe accidents at night. In this blog, we will learn everything about runway lighting that will help you fly confidently at night.

Runway Edge Lighting

Pilots must have a visual guide to the width of the runway when landing or taking off at night. The most basic runway lighting system is runway edge lights, which are a combination of white lights positioned in a row on either side of the runway. This system can be classified into high, medium, and low intensity. High and medium-intensity lighting systems can be adjusted and can vary in intensity. 

The standard that the FAA (Federal Aviation Administration) allows is that the distance between each individual runway edge light shouldn’t be more than 200 feet in Medium Intensity Runway Lights (MIRLs) system or High-Intensity Runway Lights (HIRLs) system. The only exception to this rule is at the intersections between the runway, taxiway, or any other runway. Up to a 400-foot gap at the intersections in edge lighting is authorized. 

For runways with ILS approach capability, the runway edge lights will be yellow rather than white for the last 2,000 feet of the runway, or half of the runway length for runways that are shorter than 4,000 feet in length. The yellow area creates a caution zone for landings or takeoffs on the runway because the remaining runway is low. A runway without an instrument approach only has white edge lights, while a horizontal line of red lights marks the end of the runway for both instrument and non-instrument approaches..

Runway Centerline Lights

Some larger airports have precision instrument runways that might have installed runway centerline lights. Runway centerline lighting can be defined as the row of lights reaching down to the runway's center. The centerline lights help the pilots keep their aircraft aligned during takeoff and landing, and they are installed in 50-foot intervals down the length of the runway.

The color of the runway centerline lights are white and red, which can also be used in combination.   

When the aircraft is near the runway's approach end, the lights' color is white, but as the pilot is at 3,000 feet from the end of the runway, the lights warn the pilot by transitioning to alternating white and red color. For the final 1,000 feet of the runway, the lights are red. The centerline lights are required for some CAT I aircraft  and all CAT II and III aircraft.

Touchdown Zone Lighting

The touchdown zone lighting system consists of three white lights placed to the left of the runway and three white lights placed to the right of the runway centerline lights. To mark the touchdown zone on a precision approach runway, the touchdown zone lights are used, and they are designed to help with landings in lower visibility conditions. Touchdown zone lights start 100 feet before the runway threshold and are continuously placed 3,000 feet down the runway or to the midpoint.

Approach Lighting System (ALS)

All other runway lighting is placed either on or adjacent to the runway. However, the approach lighting system (ALS) is a group of lights that are positioned on the approach area of the runway and then stop at the threshold. The purpose of this lighting system is to help the pilots transition from instrument to visual flight when they are landing. 

Most of the time, pilots see the approaching lights even before they spot the runway in poor weather. There are various configurations of approach lighting systems, but they have the same purpose and have similar elements. The different types of approach lighting systems (ALS) are SALS, SSALS, SSALR SSALF, MALSR, MALSF, ODALS, ALSF-1, and ALSF-2. 

These lights begin at the runway landing threshold. The lights are extended 2,400 to 3,000 feet for the precision approach runways, and for the non-precision approach runways, the lights are extended only 1,400 to 1,500 feet. The most basic type of approach lighting configurations has a series of seventeen white lights in a cross formation, and this lighting system is standard at regional airports. Most of the larger international airports use the ALS, which has a more complex structure with white, yellow, and red lights.

What is a Visual Approach Slope Indicator (VASI)

The Visual Approach Slope Indicator (VASI) system uses two groups of two lights, with one light  group placed in front of the other. Visual Approach Slope Indicator (VASI) lighting systems work similarly to Visual Approach Slope Indicator (VASI) lighting systems.. Both lighting systems can be found on the runway's right or left side.

Taxiway Lighting

If the taxiway and runway had the same lights, then pilots would have difficulty distinguishing one from the other. The taxiway lead on and lead off lights help pilots to visually identify and locate the intersection of the runway and taxiway at night. This lighting system uses different colors than runway lighting to prevent confusion. This system is made up of alternate green and yellow lights that branch off from the centerline of the runway and then connect to the centerline of the taxiway.

What is the Difference Between Runway and Taxiway Lighting System?

In the dark, runways and taxiways can look similar to the eyes of new or untrained pilots. However, some lighting differences will help pilots confirm whether they are entering a runway or taxiway. The runway edge lights are white, while the taxiway edge lights are blue. This is the easiest and most trustworthy way to use a lighting system to determine the type of surface you are entering. 

At international airports, there is another lighting difference that pilots can also compare. The runway centerline lights are white, and the taxiway centerline lights are green. Taxiways may not have the centerline lights at smaller airports at all.

Final Thoughts

Pilots must understand the runway lighting systems, types, colors, meaning, and spacing for safe flight operations. The runway lights help pilots make precise takeoffs and landings in bad weather conditions or at night.