Savvy Passenger Guide to Airport Lights

Airport Lights - AeroSavvy

Colorful lights cover taxiways and runways to help pilots navigate the airport. Red, blue, green, amber, and white lights glow, flash, and race across the ground. It’s time to find out what the colored airport lights mean and how pilots use them!

Note to Readers:

This guide is not intended to be a comprehensive list of airport lights. Included are lights passengers often see while driving to the airport or out the aircraft window on a typical flight.

Airport lights are fairly standard around the world, but there are minor regional differences. It’s fun to spot the variations during international travel.

If you would like more information about airport lights (and who wouldn’t), check out the More Information About Airport Lights section at the end.

 

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Taxi Lights

After an aircraft leaves the gate, the first challenge pilots face is navigating the plane to the runway for takeoff. Both day and night, airport lights make it easy to maneuver around the maze of taxiways.

Taxi Lights - Airport Lights - AeroSavvy

Blue Lights:  Taxiway edge lights are always blue. The blue taxi lights are easy to spot from the terminal and are often the first airport lights seen by passengers. Blue taxiway lights are typically illuminated after dark and during bad weather. For many airports, the blue lights are all that is necessary to mark the taxiways.

In-ground lights - Airport Lights - AeroSavvy

In-ground centerline light

Green Lights:  Green in-ground centerline lights are often installed at busy airports and airports that experience bad weather to enhance taxi guidance and safety. Unlike the blue lights used to identify the taxiway edges, green centerline lights are very bright. Pilots can see and follow them in the worst weather conditions, day or night.

The tough metal housings for in-ground lights are mounted flush with the surface of the taxiway. Only a small portion protrudes above ground. The lights are installed a few inches to the left or right of the actual painted centerline.

Blue taxi lights - Airport Lights - AeroSavvy

Blue taxiway edge lights

Green centerline lights - Airport Lights - AeroSavvy

Green centerline taxi lights at LAX

 

Singapore’s Changi Airport:  “Follow the Greens”

Singapore Safegate System - Airport Lights - AeroSavvy

Safegate Ground Lighting Control & Monitoring System

Singapore’s Changi International Airport has taken green centerline taxi lights one step further. To make taxiing easier (and safer), Changi’s green centerline lights are controlled by an automated guidance system developed by Safegate Group.

The Safegate system illuminates the green centerline lights in front of the aircraft as it taxis, providing custom guidance from gate to runway. The pilot simply follows the lights to the runway. The green lights can be seen day and night.

Without Safegate, a typical taxi clearance at Changi might be:

“KLM 836, Taxi runway two zero center via Uniform one, Victor Zulu, Whiskey Alpha, North Cross Three, Alpha Seven, Alpha One, Echo One.”     Whew!

With Safegate, the taxi clearance is:
“KLM 836, taxi runway two zero center. Follow the greens.”

The system is amazing and one reason I enjoy flying to Changi.

 

Taxiway Signs

Although not technically airport lights, taxiway signs are well illuminated and easy to see. Yellow and black signs identify taxiways. A black background with yellow characters (  A3  ) identifies what taxiway the aircraft is on. A yellow background with black characters ( A4 ) identifies a crossing taxiway.

Red signs ( 31R ) always indicate a runway. The red color reminds pilots not to proceed without permission from an air traffic controller.

Taxi Sign - Airport Lights - AeroSavvy

Aircraft is on taxiway Alpha. Taxiway Alpha-4 is ahead, hard right turn.

Taxi sign - Airport Lights - AeroSavvy

Aircraft is on taxiway Alpha-3 and approaching runway 31R-13L.

Runway Guard Lights

Wig-wag animation - Airport Lights - AeroSavvy

Runway Guard Lights (wig-wags)

In the last few years, new types of lights have been added to enhance safety. One of the most prominent are Runway Guard lights. Introduced in 1995, these flashing amber lights warn pilots that they are about to taxi onto a runway.

The basic installation consists of a dual flashing light unit. One unit is mounted on each side of the taxiway where the aircraft must stop. Taxiing past guard lights onto the runway requires a clearance from air traffic control.

Guard Light Trivia:

Pilots rarely refer to the lights as “Runway Guard lights.” We call them “Wig-Wags.”
It’s a lot easier to say “Hey captain, are you blind? The wig-wags are right there!

 

In addition to the dual flashing units, wig-wags are often installed in-ground, on the runway hold-short line. This system is really helpful during low visibility conditions.

In-ground-wig-wag - Airport Lights - AeroSavvy

Runway Guard Lights: Pilots need a clearance to cross and must use caution.

Red Stop Bar Lights

Red Stop Bar lights (also known as Runway Status Lights) are another newcomer to the taxi light family. In an effort to reduce the risk of deadly runway collisions, Stop Bar lights are being installed at many airports world-wide.

Runway Status Lights - Airport Lights - AeroSavvy

Red Stop Bar Lights. Taxiing across the illuminated red lights is forbidden (and really, REALLY dangerous).

The lights are placed along the hold-short line and are switched on and off automatically. Unlike the yellow guard lights which mean “use caution,” red stop bar lights mean STOP – Don’t even THINK about moving. When the lights are on, there is active traffic on the runway or landing imminently. The lights must be extinguished before an aircraft can proceed.

As of 2016, fifteen US airports have Runway Status lights installed with more on the way.  Look for them at busy airports. They’re really bright; you can’t miss them.

led-lamps2Airport Lighting Trivia:

You might notice a different hue and intensity of taxi and runway lights at some airports. The reason? New LED lights.

LED light prices have dropped dramatically in the past few years. Airports all over the world are changing to LEDs to lower electric bills and reduce maintenance costs. They’re bright, and they look great!

Runway Lights

Runways designed for low visibility operations (bad weather) have a lot of lights.

Note that not all runways have the same light configuration. The runway at St. Thomas, USVI, has only basic edge lighting because the weather is usually gorgeous. Foggy San Francisco, on the other hand, needs a full lighting system for low visibility weather.

Runway Lights - Airport Lights - AeroSavvy

White Runway Light - Airport Lights - AeroSavvy

Runway Edge Lights: The lights that mark the left and right edges of the runway are primarily white. The edge lights along the last 2000 feet of runway are yellow to let the pilots know that the end of the runway is approaching. This is useful information for both takeoff and landing.

Runway Threshold and End Lights:  The beginning of the usable portion of runway is marked with a row of green threshold lights. Red lights mark the end of the runway.

Runway End Identifier Lights (REILs): To further highlight the beginning of the runway, two very bright strobe lights are installed to the left and right of the runway threshold. REILs are bright and can be seen for miles in good weather. Flashing REILs can even be seen while cruising at 35,000 feet. See if you can spot some on your next flight.


Directional Lights
:

Two color light - Airport Lights - AeroSavvyAirplanes can takeoff and land in either direction on a runway. The direction used is based on wind direction.

Runway edge lights need to turn yellow in the last 2000 feet of runway. How can the lights be yellow when going one direction and white when going the other? Dual colored lens covers!

The same trick is used for centerline lights that need to be different colors when looking at them from different directions.

 

Runway Centerline Lights: Runways used for low visibility operations have white centerline lights installed every 50 ft to help pilots maintain directional control during takeoff and landing. Starting the last 3000 ft of runway, the lights alternate white and red. The last 1,000 feet of runway has solid red centerline lights.

Taxiway Lead-off Lights:  To help pilots find the taxiway after landing, alternating green and yellow “lead-off” centerline lights are often installed. The Lead-off lights help flight crews quickly exit the runway.

Centerline Light Trivia:

Runway Centerline Lights - Airport Lights - AeroSavvy

Original image: SKYbrary

Centerline lights are mounted a few inches left or right of the actual centerline. During takeoff, it’s not uncommon for one of the nose wheels to run over the lights.

If you feel a rhythmic “thump thump thump thump” on the takeoff roll, it’s the nose wheel hitting the centerline lights. Don’t worry, it won’t hurt the tires or lights. The in-ground lights are designed to withstand the weight of wide-body jets landing on them!

 

Approach Lights

Approach Light System. ©Lew Wiezorek / WK Pix Photo used with permission.

Approach Light System. ©Lew WiezorekWK Pix
Used with permission.

When driving near an airport, it’s hard to miss dozens of orange light poles near the runways. The forest of lights are part of the Approach Lighting System.

There are several different configurations for approach lights. The type of instrument approach to the runway determines the design of the approach lights. Designs also vary in different parts of the world. The purpose of all the designs is the same: provide pilots with the visual cues necessary to properly align the aircraft for landing during bad weather.

Sequenced Flashing Lights - Rabbit - Airport Lights - AeroSavvy

ALSF-2 Approach Lighting System

The animated image is an example of ALSF-2 lights. The full name is “Approach Lighting System with Sequenced Flashing Lights – Configuration 2.”  See why we use acronyms?

The white lights that appear to shoot toward the runway are called sequenced flashing lights.  Pilots call them “the rabbit,” possibly named after the mechanical rabbit used during greyhound dog racing.

Runway rabbits are as bright as REILs and can often be seen during the cruise portion of the flight. They are another good light to watch for on a clear night when the in-flight movies are boring.

Did you know…

The first airport to use runway lights was the Cleveland, Ohio Municipal Airport (now Hopkins International) way back in 1930!

Touchdown Zone Lights

Runway Threshold Lights - Approach Lights - Airport Lights - AeroSavvy

In-ground runway lights for bad weather. Touchdown zone lights start just beyond the row of green threshold lights.
Photo by: Josbert Lonnee

Touchdown zone - Airport Lights - AeroSavvy

Original image source: SKYbrary

Approach lights guide pilots to the Touchdown Zone Lights (TDZL) on the runway.

Touchdown Zone lights consist of 30 rows of white lights on each side of the centerline down the first 3000 feet of runway. That’s 180 in-ground lights!

The purpose of the lights is exactly what you would guess from the name. Pilots want to touchdown within the touchdown zone to ensure adequate runway is available to stop the aircraft. If the aircraft will touchdown beyond this area, it’s time to go around and try again.

Amber runway light - Airport Lights - AeroSavvyHow many lights are used for a runway?

A runway that can handle instrument approaches from both directions can have more than 1,150 lights!

That number includes the edge, centerline, touchdown zone, and ALSF-2 lights. A few hundred more lights can be used, depending on the length and configuration of the runway.

Next time you see “Airport Use Tax” on an airline ticket, this is one of the reasons why!

Advanced Airport Light Spotting: The PAPI

PAPI array - Airport Lights - AeroSavvy

PAPI Array in Vancouver, BC

PAPI stands for Precision Approach Path Indicator. The PAPI is a set of four projectors that each contain a white light, red filter, and precisely adjusted lenses.

During final approach, aircraft fly about a 3 degree slope (glidepath) down to the runway. The PAPI gives pilots an easy way to visually verify that the aircraft is on the correct glidepath.

When the aircraft is above the correct glidepath, all four PAPI lights will appear white. Pilots will see four red lights if the aircraft is too low,

PAPI animation - Airport Lights - AeroSavvy

Precision Approach Path Indicator

The PAPI displays two white and two red lights when the aircraft is on the correct glidepath.

As a passenger, the PAPI is a little more challenging to spot than other lights. Look for the four light array near the end of the runway. They can be located on either side. The best time to spot them is at the beginning of the takeoff roll or just before touchdown. When viewed from the ground, all four lights will be red.

When airborne, you might catch a glimpse of the PAPI as the aircraft turns onto final approach.

On a long final approach, it’s not uncommon to see four red lights. The pilots will maintain altitude until intercepting the 3 degree glidepath. The PAPI will then display two whites/two reds during final descent to the runway.

Keep your eyes open for the PAPI. The system is used all over the world. Bonus points if you spot PAPI’s cousin, the VASI.

Aerodrome (Airport) Rotating Beacon

Rotating-beacon - Airport Lights - AeroSavvy

Rotating Beacon at Bowman Field, Louisville, KY (KLOU). Green/White flashes indicate a public airport.

Without a doubt, my favorite airport light is the granddaddy of them all: the Aerodrome Rotating Beacon. The origins of the beacon go back to the 1920’s. Most every airport in the US has one. Outside of the US and Canada, airport beacons are rare.

Aerodrome beacons operate from dusk to dawn. The beacons help pilots locate air fields and can be seen for miles. Public use airport beacons flash green and white.

In the United States, different flashing colors identify the type of facility. I had to memorize these when I was a student pilot:

  • White and Green – Land airport
  • White and Yellow – Water airport
  • Green, Yellow, and White – Heliport
  • White, White, Green – Military airport
  • White, Green, Red – Hospital or Emergency Services Heliport

In Canada, many airports are identified by beacons that emit one white flash, 20-30 times/minute. Heliport beacons display a series of four quick white flashes (Morse code for the letter “H”), several times a minute.

Transcontinental Airway Beacon. - Airport Lights - AeroSavvy

Airway beacon photo:
Mark Wagner CC BY 4.0

Rotating Beacon History:

In the 1920’s, the United States Congress approved the Transcontinental Airway System to enable air mail pilots to fly across the country at night.

White rotating beacons, mounted on towers, were spaced every 10 miles along the route. Beacons located at airports had flashing green lights mounted on the tower below the beacon. By 1933, 1,500 beacons were installed on the airway system.

Lighted airways were quickly replaced by radio navigation in the 1930’s. The airport beacons remained and are still used at US airports.

Airway-beacons - Airport Lights - AeroSavvy

 

If you’ve been keeping up, there’s a good chance you know way more about airport lights than Platinum-Level-Guy snoring in the aisle seat. Keep your eyes out the window and check out those lights.


You Might Also Enjoy:

NavLightsThe Savvy Passenger Guide to Airplane Lights
Everything you ever wanted to know about airplane lights!


More Information About Airport Lights:

FAA Aeronautical Information Manual (pdf)
Chapter 2: Aeronautical Lighting and Other Airport Visual Aids. Everything a pilot needs to know about airport lights, signs, and markings.

Can I Descend?
Overview of US approach lighting systems by Ranier Flight Service.

Runway Status Lights – Summary of system with video by the FAA.

Precision Approach Path Indicator  – (Wikipedia)

Transcontinental Airway System – History of the 1920’s airway system.

FAA document: Design and Installation Details for Airport Visual Aids (pdf)
300 pages: Installation and specs of airport lights. For readers who like to dig deep.

A Quick Reference to Airfield Standards (pdf)
Chapter 2 discusses airfield lighting standards.

 

AeroSavvy is written by Ken Hoke. Since 1984, Ken has loitered the skies in many vehicles, most notably the classic Douglas DC-8. He currently frustrates air traffic controllers in the US, Asia, and Europe as a Boeing 767 captain for a package express airline.
Ken can be reached here or any of these fine social media outlets:   

16 thoughts on “Savvy Passenger Guide to Airport Lights

  1. Steve Mandrackie

    Capt. Hoke
    Thank you for shedding some “light” on one of the many aspects of airport procedure. Your easy to understand explanations are a great comfort to us non-rated types that find the airport a most perplexing place.

    Reply
  2. John Winter

    Thanks for the refresher. Even as a GA private pilot, I sometimes find the array of lights at some of the Class B airports confusing. Always a pleasure to read AeroSavvy!

    Reply
    1. Ken H. Post author

      Hi John,

      Thanks for the comments, I really appreciate it. There have been a lot of new developments in lighting technology since I started flying over 30 years ago. It’s hard for us Class B “regulars” to keep up, too! Just the other day, I saw some oddball lights in Vancouver that I hadn’t seen before. Something new every day.

      Thanks for reading!
      Ken

      Reply
  3. Jenn_Niffer

    Yet another great article! Airfield lights at night are better than Christmas! We just put new LED lights in the freshly re-paved north runway. And you’ll be happy to know we’re putting an all-new ALSF system in at the cargo airport. As for the “wig-wags,” the airfield maintenance crews call them that too. In fact that’s the only name I knew for them until just now! :o)

    Reply
    1. Ken H. Post author

      Thanks Jennifer!! I really like the colors and brightness of the new LEDs (both aesthetically and operationally). They just look really cool. It would be interesting to know the impact LEDs have on an airport’s electric bill. If I only knew an accountant that worked at an airport…

      Thanks for the kind words.
      Here’s to keeping the wig-wags wigging and wagging!

      Ken

      Reply
  4. Ehsan

    Ken,

    Excellent article as always. I always loved taxiway and runway lights since i was a kid. They are so different. They are so beautiful and exciting.

    Thank you again for teaching us something new

    Reply
  5. AM

    Hi everyone i like aviation too much and my major at school is aviation and now Im studying for ultra light. thanks for your helping for runway lights.

    Reply
  6. Bella

    Hi Ken,

    I’m amazed by the lively animation picture!! Btw, do you know about ‘No-entry bar’? Recently, I have found it from ICAO (annex 14, section 5.3.29)but I cannot find any information online. Is it different from stopbar?

    Reply
    1. Ken H. Post author

      Hi Bella,

      No-Entry bars are located on taxiways that are one-way (like highspeed runway exits) or where aircraft are not permitted. The warning is usually painted on the ground and is sometimes accompanied by red lights.
      No-Entry Bar

      Stop Bars can be controlled (like a red traffic light). No-Entry areas are typically always no-entry.
      Great question. Thanks for reading!

      Reply
  7. Mayank.Gupta

    Just stumbled upon your blog and you solved my two queries, airport lights and lights on airplanes. You have no idea how happy I am feeling right now that there’s a guy out there who’s writing these easy to read, mildly funny, and super informative articles for aerophiles (just invented the word!!) like me. Thank you so much, good sir!

    Reply
    1. Ken H. Post author

      Hi Mayank,

      I’m glad you found the airport and airplane lighting articles informative. Those are two of my favorites. Thanks for reading!

      Ken

      Reply

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