Airport Lights – Types, Colors, and Functions Explained

Understanding Airport Lighting Systems

Airport lighting systems form a complex, visual language that guides pilots safely from the sky to the gate. This network is essential during night operations and in low-visibility conditions, where every color, pattern, and intensity communicates critical information. It helps pilots maintain approach paths, identify runways, avoid obstructions, and maneuver on the ground. This visual guidance transforms darkness into a clear pathway, ensuring both the safety and efficiency of every takeoff and landing.

Touchdown Zone Lights (TDZL)

Engineered for precision approach runways, Touchdown Zone Lights (TDZL) create an unmistakable visual target for landing. They are composed of two rows of white light bars, arranged symmetrically on either side of the runway centerline. These lights begin 100 feet past the landing threshold and extend for 3,000 feet or to the runway’s midpoint—whichever is shorter. By clearly illuminating the ideal landing area, TDZLs help pilots make a smooth, safe touchdown, especially in darkness or low visibility.

Runway End Identifier Lights (REAL)

To help pilots quickly and positively identify the runway threshold, airports employ Runway End Identifier Lights (REAL). The system is simple but effective—a synchronized pair of high-intensity strobes, one positioned on each side of the runway’s approach end. Their distinct, pulsing flashes act as a powerful beacon, drawing the pilot’s attention directly to the start of the landing surface.

Rails prove most valuable in challenging conditions, in:

• Identifying runways surrounded by a high concentration of city lights that could cause confusion.

• Providing contrast when the runway surface blends with the surrounding terrain, such as in desert or snow-covered environments.

• Marking the runway end during periods of reduced visibility.

Centerline and Edge Lights

Once past the threshold, pilots rely on two primary systems to stay oriented on the runway surface: Runway Edge Lights and Runway Centerline Lights.

Complementing the edge lights are the Runway Centerline Lights, embedded flush with the pavement. Spaced at 50-foot intervals, they form a precise line for pilots to follow, ensuring the aircraft remains perfectly aligned during its takeoff roll or landing rollout.

The centerline lighting system also features an intelligent color-coding scheme to inform pilots of the remaining runway distance:

• White: Until the final 3,000 feet.

• Alternating Red and White: From 3,000 feet to 1,000 feet remaining.

• Solid Red: The last 1,000 feet.

This progression serves as a clear visual countdown, warning pilots that the runway is nearing its end.

Taxiway Lighting: Types and Importance

After landing and vacating the runway, aircraft follow taxiway lights to the terminal. This system uses a distinct color scheme—primarily blue and green—to prevent any confusion with runway lighting, a fundamental safety feature for all ground operations.

Taxiways use two primary types of lights for navigation:

• Taxiway Edge Lights: Steady, elevated blue lights that outline the taxiway’s boundaries.

• Taxiway Centerline Lights: Green lights embedded flush with the pavement that provide a precise path, which is crucial for navigating complex intersections, especially in low visibility.

Together, this system of blue and green lights creates an intuitive and safe ground navigation network. The clear demarcation prevents pilots from accidentally entering a runway—an event known as a runway incursion—and ensures an orderly flow of traffic. At critical intersections where a taxiway meets a runway, red stop bar lights are often installed.

Approach Lighting Systems (ALS)

The final approach is a critical phase where pilots transition from instrument-based to visual flight, especially in poor weather or at night. The Approach Lighting System (ALS) proves essential, creating a luminous pathway that visually extends the runway and guides the aircraft toward the landing threshold.

An ALS consists of high-intensity light bars, crossbars, and strobes extending from the runway threshold into the approach area. The system’s length depends on the runway type:

• Precision Instrument Runways: 2,400 to 3,000 feet, for landings in very low visibility.

• Non-Precision Instrument Runways: 1,400 to 1,500 feet.

Many advanced ALS configurations feature Sequenced Flashing Lights (SFL), commonly called ‘the rabbit.’ This system is a series of brilliant white strobes that fire in succession, creating a ball of light that seems to race toward the runway. This dynamic cue provides powerful directional guidance, helping pilots instantly acquire the centerline and confirm their alignment for a safe landing.

Visual Approach Slope Indicator (VAST)

As the ALS guides a pilot toward the runway, the Visual Approach Slope Indicator (VAST) provides the next layer of guidance: vertical alignment. This system helps to maintain the correct descent angle. Its lights, positioned alongside the runway threshold, are visible from 3–5 miles during the day and over 20 miles at night, offering a clear reference for the final approach.

The VAST uses its simple and intuitive color-coded system. It typically consists of two bars of lights, a near bar and a far bar. Pilots interpret their altitude based on the colors they see, following a well-known mnemonic:

• White over White: Indicates the aircraft is too high (mnemonic: “high as a kite”).

• Red over White: Indicates the aircraft is on the correct glide path (mnemonic: “you’re all right”).

• Red over Red: Indicates the aircraft is too low (mnemonic: “and you’re dead”).

This straightforward visual cue allows for immediate correction, ensuring the aircraft remains on the optimal glide path. The system is precisely calibrated to guide aircraft safely over any obstacles within the approach corridor, providing clearance within 10 degrees of the extended runway centerline and up to 4 nautical miles from the threshold.

Precision Approach Path Indicator (PAPI)

While the VAST is effective, the Precision Approach Path Indicator (PAPI) is its more modern and accurate successor. A PAPI system uses a single horizontal bar of four lights—unlike the VAST’s two-bar setup—typically installed on the left side of the runway. This streamlined design offers pilots far more granular feedback on their descent.

The key advantage of the PAPI is its five distinct indications, which allow for finer adjustments to the approach angle. The combination of red and white lights reveals a pilot’s precise position relative to the optimal glide path:

• Four white lights: Significantly too high.

• Three white, one red: Slightly high.

• Two white, two red: On the correct glide path.

• One white, three red: Slightly low.

• Four red lights: Significantly too low.

This enhanced detail is a major improvement over the VAST’s three simple indications. It allows pilots to discern even slight deviations from the glide path, enabling a more stable and exact descent. Due to its superior accuracy, the PAPI has become the international standard, largely replacing older VAST systems at airports worldwide.

Airport Beacons and Their Functions

The airport beacon is a powerful rotating light that helps pilots find and identify an airport from a distance, especially at night or in low visibility. Operating from dusk until dawn, and often during poor weather, it serves as the first visual confirmation of an airport’s location.

The beacon’s key feature is its color-coded flashes. The specific sequence and color of the light immediately tell a pilot what type of facility they are approaching. This is simple yet effective system eliminates ambiguity and is standardized across the industry. The most common combinations include:

• White and Green: Lighted civilian land airport.

• White and Yellow: Lighted civilian water airport (seaplane base).

• Two White Flashes and a Green Flash: Military airport.

• White, Yellow, and Green: Lighted heliport.

By recognizing these patterns, pilots can quickly verify that they are heading toward the correct type of airfield. This proves vital during the initial phases of a visual approach, providing essential orientation and confirming the airport’s position relative to other ground lights. While modern GPS has added layers of navigational precision, the airport beacon remains a fundamental and reliable tool in aviation safety.

Control of Airport Lighting

While major airports have 24/7 staff managing lighting, many smaller airfields without control towers use Pilot-Controlled Lighting (PCL). This system allows pilots to activate runway lights themselves, especially after hours.

Often known by its technical name ARCA (Aircraft Radio Control of Aerodrome Lighting), the system allows pilots to activate and adjust the intensity of runway and taxiway lights using their aircraft’s radio.

The process is standardized and straightforward. By keying the mic a specific number of times within a five-second window, the pilot can set the lighting intensity for optimal visibility:

• Three clicks: Low-intensity lighting.

• Five clicks: Medium-intensity lighting.

• Seven clicks: High-intensity lighting.

Once activated, the lights remain on for a 15-minute cycle—an energy-efficient approach that saves costs for smaller airports. This ensures the airfield is lit only when needed, providing pilots the essential cues for a safe approach, landing, and taxi. If more time is required, the pilot can simply repeat the sequence to reset the timer.

Standards and Regulations for Airport Lighting

Airport lighting is governed by strict standards and regulations to ensure global consistency and safety. This uniformity means pilots can instantly recognize and trust the visual cues at any airport in the world, regardless of location or weather.

Two primary authorities set these rules: the International Civil Aviation Organization (ICAO) for global standards, and the Federal Aviation Administration (FAA) in the United States. ICAO’s Annex 14 provides the foundational requirements, detailing requirements for the design, color, intensity, and maintenance of every light on an airfield. For an airport to receive certification, compliance with these regulations is not optional—it’s mandatory.

This strict adherence to standards guarantees that pilots receive the same clear, unambiguous visual guidance everywhere they fly—whether taking off, landing, or taxiing. This consistency proves vital in low-visibility conditions, where pilots depend almost entirely on these lights for safe navigation. Today, these regulations also address modern concerns, promoting energy efficiency and minimizing light pollution without compromising the highest safety standards.