To see or not to see, that is the question: Airport Lighting Tutorial

…Airport lighting is the answer

Whilst this might be considered to be a boring topic for some, it is a very important topic in all actuality. Airport lighting can save your life and those of others. Airport lighting can even help you make a nice, smooth touchdown. In this essay, I will briefly discuss different lighting systems such as VASI, RCLS, and others. Per usual fashion, I will include visual aids to provide a better understanding of what I’m trying to convey. Let’s begin…

The majority of airports, no matter the size or location, have some type of lighting. The variety and type of lighting systems depend on how complex the layout, and volume of traffic of that particular airport. Luckily, for you travellers of the Infinite Flight world and within real world aviation, airport lighting is standardised.


These help pilots to identify an airport at night and are normally operated from dusk until dawn. However, this is not a requirement for airports. If the ceiling is less than 1000 ft and/or the ground visibility is less than 3 statute miles (VFR minimums) the beacon is switched on. Ultimately, it is the responsibility of the pilot to determine if weather conditions meet VFR requirements.

The combination of colours from the beacon indicate the type of airport (Fig 1):
Flashing white and green are for civilian airports
Flashing white and yellow are for water airports
Flashing white, yellow, and green are for a heliport
Two quick white flashes alternating with a green flash are for airports you should probably not be landing at…they are for military airports

These are intended to assist pilots transition from instrument flight to visual flight landing approaches. Some systems include sequenced flashing lights that make it appear as though a ball of light is traveling toward the runway at high speed. Each system’s configuration depends on whether the runway is a precision or non-precision instrument runway.

Before you ask…the easiest explanation of a precision runway is a runway which has non-visual precision approach aids: indicators for a touchdown zone, fixed-distance markers, side strips, etc. The easiest explanation of a non-precision runway is a runway which utilises an instrument approach whilst using air navigation with only horizontal guidance.

Visual Glideslope Indicator Systems
Although there are multiple systems, I will only cover two systems which I personally have encountered during my time in the air. Visual glideslope indicators help to provide pilots with glidepath information and can be used for day or night approaches. In theory, if the pilot adheres to the glidepath provided by the system, s/he should have adequate obstacle clearance and should land within the touchdown zone.

First, the Visual Approach Slope Indicator (VASI) system. It is the most common visual glidepath system. VASI consist of lights arranged in bars that are either 2-bar or 3-bar systems. The 2-bar VASI has near and far light bars (Fig 2). The principle of VASI is to provide a colour differentiation between red and white to help indicate that you are on the correct glidepath. To help you remember you’re on the right glidepath, there’s a saying I was taught when I was training for my PPL: 'Red over white, you’re all right.'

Second, the Precision Approach Path Indicator (PAPI) system. This is what Infinite Flight uses for its airports. PAPI uses lights similar to that of the VASI system, except they are installed in a single row, normally on the left side of the runway. PAPI, like VASI, provide only one visual glidepath that is normally set at 3°. (Fig 3)


These are various lights that help pilots identify parts of the runway complex. These assist a pilot in safely making a takeoff or landing during night operations.

Runway End Identifier Lights (REIL) - These help airports to provide rapid and positive identification of the approach end of a particular runway. It consists of a pair of synchronised flashing lights located laterally on each side of the runway threshold. REILs can be either omnidirectional or unidirectional facing the approach area. (Fig 4)

Runway Edge Lights - These lights are used to outline the edges of runways at night or during low visibility. These lights are classified to the intensity they are capable of producing: high intensity runway lights (HIRL), medium intensity runway lights (MIRL), and low intensity runway lights (LIRL). These lights are white, except on precision runways where amber lights are used on the last 2000 ft or half the length of the runway, whichever is less. The lights marking the end of the runway are red. (Fig 5)

In-Runway Lighting - Runway Centreline Lighting System (RCLS) are specifically used on precision runways to help facilitate landing under adverse weather conditions. They are normally spaced at 50-foot intervals and are located within the runway centreline. When viewed from the landing threshold, they remain white-coloured until the last 3000 ft of the runway: they begin to alternate with red for 2000 ft and then the last remaining 1000 ft all centreline lights are red. (Fig 6)

Touchdown Zone Lights (TDZL) - These consist of two rows of transverse light bars disposed symmetrically about the runway centreline. They consist of steady-burning white lights that start 100 ft beyond the landing threshold and extend to 3000 ft beyond the landing threshold or to the midpoint of the runway, whichever is less. (Fig 7)


Similar to runway lighting, these are various types of lights which help pilots identify areas of the taxiway and any surrounding runways.

Omnidirectional - These lights outline the edges of the taxiway and are blue in colour. The intensity of these lights are controlled by ATC and have variable intensity that can be increased or lowered when requested by pilots. Some airports also have taxiway centreline lights that are green in colour.

Clearance Bar Lights - These consist of three in-pavement steady burning yellow lights. These help to increase the visibility of the holding position in low visibility conditions in addition to indicating the location of an intersecting taxiway.

Stop Bar Lights - These consist of a row of red, unidirectional, steady burning lights installed across the entire taxiway at the runway holding position. ATC use these lights to confirm clearance to enter or cross an active runway in low visibility conditions (usually below 1200 ft Runway Visual Range RVR)).


Last but most certainly not least, and in my opinion one of the coolest, is the Runway Status Lights (RWSL) System. The RWSL System provides warning lights on runways and taxiways, illuminating when it is unsafe to enter, cross, or begin takeoff on a runway. Currently, there are two types: Runway Entrance Lights (REL) and Takeoff Hold Lights (THL).

REL provide a warning to aircraft crossing or entering a runway from intersecting taxiways that there is conflicting traffic on the runway. (Fig 9)

THL provide a warning signal to aircraft in position for takeoff that the runway is occupied and it is unsafe to take off. (Fig 10)

FIGURES 1 - 10

Figure 1 - Airport Beacons

Figure 2 - Two-bar Visual Approach Slope Indicator (VASI) system

Figure 3 - Precision Approach Path Indicator (PAPI) system

Figure 4 - Runway End Identifier Lights (REIL)

Figure 5 - Runway Edge Lights

Figure 6 - In-Runway Lighting

Figure 7 - Touchdown Zone Lights (TDZL)

Figure 8 - Taxiway Lights


Figure 9 - RELs

Figure 10 - THLs


As always, I sincerely hope you enjoyed reading about this topic, but more importantly, I hope you might have learned something new.


A particularly special thank you to @lucaviness! Thank you for showing this old guy how to make my posts look great 😊


Your tutorials never fail to impress. Great job!


Very interesting and in-depth tutorial!! Thanks! Do you also happen to know whether the white flashing (in intervals) lights on top of the tower (two lights to be exact) are also standardised worldwide as I have never seen a green light like it’s in IF (and what you wrote on) on an IRL tower or is this something that’s done differently in Germany/Europe?

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Thank you very much @KaiM! I am truly appreciative of your comment! I will always try to provide fun and informative content for the community 😬

Hi @JulianB! Thank you for your interest and question. If I am understanding your question correctly: you’re asking whether airport lighting in general is standardised globally, correct?

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Partly, yes, but more exactly I was wondering about two white flashing lights on the tower at my home airport (and the lack of a green one to my knowledge). Would be interesting to hear if that’s an exception or something.

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@JulianB I believe you’re referring to the Aerodrome Beacon. These are mounted on top of a towering structure, often the control tower, however may be above other buildings of the airport. The beacon may be an omnidirectional flashing xenon strobe, or it may be an aerobeacon rotating at a constant speed, which produces the visual effect of flashes at regular intervals, similar to that of a lighthouse.

Oh, and of course, another great tutorial, Brandon. Never fail to impress me or the community. I think the title is my favorite part. 😝


I think I understand your question. Yes, what you’re seeing is completely ‘normal’. Airport beacons can be an omnidirectional capacitor-discharge device, or it can rotate at a constant speed, which produce the visual effect of the flashes I think you’re referring to.

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Thanks @Z-Tube for answering the question as I was typing it lol. And thank you very much for comment! I am glad you found it informative and hopefully a little entertaining. The title, as in most cases when one is writing an essay, came to me after I finished. Kinda cute, huh? 😂

Haha, no worries. I felt bad answering it over you, but I was so tempted to respond. Nonetheless, you did a phenomenal job on this!

Feel free to add the Aerodrome Beacon to the post :)

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Never apologise for giving the answer if you have it, that’s what a community is for 😉 Plus, you’re much faster at typing than I obviously am 😂

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Excellent topic Brandon. I hope you’re keeping well :)

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Thank you very much Darragh! I hope I am making BAVA proud 😊

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Well done! A very in-depth, detailed, and helpful tutorial. Thanks, Brandon! I’m bookmarking this now.

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Thank you @Butter_Boi! I am very grateful you found it to be a detailed and helpful tutorial :)

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@Z-Tube and @anon71974898, thank you very much for your explanations, that makes sense! Any idea why I never saw that green signal IRL?

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Amazing tutorial ! Thanks :)

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Fantastic as per usual!

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Great Tutorial… thanks!!

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Thanks for putting in the work here to
" ENLIGHTEN" the community with this necessary aviation operations information !

Hopefully as IF progresses with be able to realize a
tangible benefit from more and more of this in the game/sim

thank you !