What is FALS in Aviation? (Full Approach Lighting System)

Aviation is a complex and highly regulated industry, with an emphasis on safety and efficiency. One crucial aspect of aviation is the use of lighting systems to guide pilots during takeoff, landing, and taxiing. The Full Approach Lighting System (FALS), also known as Approach Light System (ALS), is an essential component of airport infrastructure that assists pilots during their final approach to the runway.

The FALS is a series of lights and visual aids located along the approach path leading to the runway. It provides pilots with visual references to help them align the aircraft correctly and gauge their altitude as they descend towards the runway. These lighting systems play a vital role, particularly during low visibility conditions such as fog or night operations, when pilots heavily rely on visual cues to maintain a safe approach.

Components of the Full Approach Lighting System

The Full Approach Lighting System consists of various lighting fixtures strategically placed along the approach path. These fixtures are designed to convey vital information to pilots and assist them in making precise judgments during landing. Let’s explore the key components of the FALS:

1. Approach Lighting Towers (ALT)

At the beginning of the approach path, pilots encounter Approach Lighting Towers (ALT). These towers consist of high-intensity lighting fixtures, typically arranged in a bar configuration. The lights are white, and their spacing gradually decreases as the aircraft gets closer to the runway. The purpose of ALT is to provide pilots with a visual reference of the aircraft’s position and height above the ground. By observing the decreasing spacing of the lights, pilots can gauge their rate of descent and adjust accordingly.

One example of an Approach Lighting Tower (ALT) is the PAPI.

The Precision Approach Path Indicator (PAPI) is a standard component of ALT. It consists of multiple light units, typically four, arranged in two pairs. Each unit emits a beam of light at a specific angle towards the approach path. When the aircraft is approaching at the correct angle, the pilot observes a combination of red and white lights. If the aircraft is too low, the pilot sees more red lights, indicating the need to raise the altitude. On the other hand, if the aircraft is too high, more white lights are visible, signaling the need to descend.

2. Runway End Identifier Lights (REIL)

As pilots progress further along the approach path, they encounter Runway End Identifier Lights (REIL). These lights are typically a pair of synchronized flashing lights and are installed on either side of the runway threshold. The purpose of REIL is to provide pilots with a clear indication of the runway’s location and direction. They serve as an additional visual cue to help pilots align their aircraft with the runway.

Did you know? The Runway End Identifier Lights (REIL) are often accompanied by other visual aids, such as a VASI or PAPI system, to enhance pilots’ situational awareness.

3. Touchdown Zone Lights (TDZL)

Closer to the runway threshold, pilots encounter Touchdown Zone Lights (TDZL). These lights are typically installed in two rows on either side of the runway centerline and mark the touchdown zone—the area where the pilot aims to land the aircraft. The TDZL helps pilots judge their descent rate and ensure their smooth touchdown at the desired point on the runway.

The Touchdown Zone Lights (TDZL) consist of a series of lights that are typically white, and their intensity increases as they get closer to the runway threshold. These lights provide pilots with a clear visual reference, allowing them to make precise adjustments to their aircraft’s glide path and touchdown point.

One example of Touchdown Zone Lights (TDZL) is the Rabbit Lights.

Some airports also have a variation of Touchdown Zone Lights known as Rabbit Lights. Rabbit Lights are a sequence of white lights that extend along the runway centerline beyond the touchdown zone. The purpose of these lights is to provide additional visual cues to assist pilots in maintaining their alignment with the runway during landing.

Advantages of the Full Approach Lighting System

The Full Approach Lighting System (FALS) offers numerous advantages that significantly enhance the safety and efficiency of aircraft operations. Here are some key benefits of implementing FALS:

1. Enhanced Visibility

One of the primary advantages of the Full Approach Lighting System is its ability to enhance visibility for pilots. The combination of strategically placed lights, such as Approach Lighting Towers (ALT), Runway End Identifier Lights (REIL), and Touchdown Zone Lights (TDZL), provides pilots with clear visual references during challenging landing conditions. This increased visibility allows pilots to make precise judgments while maintaining a safe approach.

2. Improved Safety

The Full Approach Lighting System plays a crucial role in ensuring the safety of aircraft operations. By providing pilots with reliable visual cues and references, FALS helps them maintain the correct glide path, descent rate, and alignment with the runway. This reduces the chances of runway excursions, hard landings, and other potential safety risks.

3. Precision Landing

The presence of the Full Approach Lighting System enables pilots to execute precision landings. The combination of lights, including the Precision Approach Path Indicator (PAPI) and Touchdown Zone Lights (TDZL), allows pilots to precisely gauge their altitude, glide path, and touchdown point. This level of precision is essential, particularly for large commercial airliners, as it ensures a smooth and controlled landing.

By providing pilots with clear visual references during their final approach, the Full Approach Lighting System (FALS) significantly enhances the safety and efficiency of aircraft operations. The strategically placed lighting fixtures, such as Approach Lighting Towers (ALT), Runway End Identifier Lights (REIL), and Touchdown Zone Lights (TDZL), work together to provide pilots with the necessary visual cues to align their aircraft and make precise judgments during landing.

For More: What is MRO in Aviation? (Maintenance And Repair Organization)