Aerodrome lights
Learning objectives
- State the colour each main aerodrome light shows: threshold, runway end, runway edge, taxiway centre line, taxiway edge and stop bar.
- Explain how to read a PAPI (precision approach path indicator) and what an "on slope" indication does and does not guarantee.
- Identify the runway centre line colour code and the yellow edge-light zone, and calculate how much runway remains.
- Identify the lights at taxiway runway-holding positions and state what you do at each.
The idea
At night a lit airfield is a language written in colour. Every colour answers the same question: how much trouble am I in? White means normal, a guide to follow. Green means go on, this is the right place. Yellow means be careful. Red means stop, danger, or the end. If you learn that one pattern, most of the individual lights explain themselves. You then only need to remember a few exceptions, and the shape of each light group tells you where on the airfield you are.
Who has to follow this lighting standard
The EU lighting design standard applies to certified aerodromes. These are aerodromes open to public use that serve commercial air transport and have a paved instrument runway of 800 m or more.
Many small general aviation fields fall outside it and are lit, or not lit, under national rules. A Member State can also exempt a very quiet aerodrome. So never assume that every airfield has every light described below. A night field with no lights is day-only.
Before a night flight, read the aerodrome entry for the lighting that exists and check the NOTAMs for outages, for example a PAPI or approach lights out of service.
The aerodrome operator must originate a NOTAM when the major parts of the lighting go out of service or come back.
The colour convention
- White (often "variable white", white whose brightness can be turned up and down) is used for the approach lights, runway edge, runway centre line and touchdown zone.
- Green is used for the threshold, the wing bars, the taxiway centre line and runway turn pads.
- Red is used for the runway end, stopways, stop bars and the no-entry bar.
- Yellow is used for the last part of the runway edge, the runway exit indicator lights, the runway-holding position warning lights and the alternating taxiway centre line.
- Blue is used for the taxiway edge.
| Colour | Where you meet it | What it tells you |
|---|---|---|
| White | Approach lights, runway edge, runway centre line, touchdown zone | Normal guidance: follow it |
| Green | Runway threshold and wing bars, taxiway centre line, runway turn pad | The right place: carry on |
| Blue | Taxiway edge | The paved edge is here |
| Yellow | Last part of the runway edge, rapid exit indicator lights, runway guard lights, intermediate holding position lights, taxiway centre line alternating with green | Be careful |
| Red | Runway end, stopway, stop bars, no-entry bar, side rows of the CAT II/III approach, last part of the runway centre line, edge lights before a displaced threshold (seen from the approach) | Stop, danger or the end |
Describe this figure
The table has one row for each colour, with three columns: the colour, where you meet it, and what it tells you. White lights are the approach lights, runway edge, runway centre line and touchdown zone, and mean normal guidance. Green lights are the threshold and wing bars, the taxiway centre line and runway turn pads, and mean the right place, carry on. Blue lights mark the taxiway edge. Yellow lights are the last part of the runway edge, the rapid exit indicator lights, the runway guard lights, the intermediate holding position lights and the alternating taxiway centre line, and mean be careful. Red lights are the runway end, stopways, stop bars, the no-entry bar, the side rows of the CAT II/III approach, the last part of the runway centre line and edge lights before a displaced threshold seen from the approach, and mean stop, danger or the end.
The figure is a table with one row per colour, giving where you meet it and what it tells you.
A word on brightness. Intensity is adjustable, and lights bright enough for fog are far too bright in clear air at night. A sudden change in brightness between the approach lights and the runway lights can make you think the visibility is changing.
If the lights dazzle you or look too dim, ask ATC or the flight information service to change the intensity. Do not carry on with an approach where the visual picture is washed out.
A fixed light does not flash. A barrette is three or more lights close together in a line across the path, which looks like a short bar from afar.
Finding the airfield
An aerodrome beacon shows where an aerodrome is from the air. It is provided at a night aerodrome where aircraft navigate mainly visually and either visibility is often reduced or the field is hard to pick out among other lights or terrain.
The EU text says only that the beacon shows white flashes, or coloured flashes alternating with white. The ICAO standard names the colour: green at a land aerodrome, yellow at a water aerodrome. So a land aerodrome beacon is white only, or white alternating with green. The total rate is 20 to 30 flashes per minute.
An identification beacon is a separate light that tells you which airfield you are looking at. At a land aerodrome the ICAO standard has it flash green, sending the identification letters in Morse code at 6 to 8 words per minute.
Approach lights
Approach lights give you alignment, a sense of roll, and a rough idea of the distance left to the runway. The better the instrument approach, the longer and richer the pattern.
- A simple system is a row of lights on the extended centre line, whenever possible at least 420 m long, with a crossbar at 300 m from the threshold.
- A CAT I system (for the basic category of precision approach) extends, wherever possible, 900 m from the threshold with a 30 m crossbar at 300 m.
- A CAT II/III system (for the lower-minima precision categories) has a 900 m white centre line, plus two side rows of red barrettes close to the threshold and crossbars at 150 m and 300 m.
- Where the centre line is made of barrettes, a flashing light on each barrette can fire twice a second in sequence toward the threshold. Pilots call this the "running rabbit".
Describe this figure
Four strips show the extended runway centre line in plan view, with the threshold, drawn as a green bar, at the right of each. The simple system is a single row of white lights at least 420 m long with one crossbar at 300 m. The CAT I system is a longer row of white lights, 900 m where possible, with a 30 m crossbar at 300 m. The third strip shows the CAT I row made of barrettes, each with a flashing light beside it that fires in turn toward the threshold, the running rabbit. The fourth strip is the CAT II/III pattern, a 900 m white row with crossbars at 150 m and 300 m and two red side rows close to the threshold.
The figure is a plan view with the threshold at the right. It shows four patterns: the simple row with one crossbar, the CAT I row, the CAT I barrettes with the flashing rabbit, and the CAT II/III pattern with red side rows.
Reading the PAPI
A PAPI gives you the approach angle you need to clear obstacles and reach the threshold safely. It is a bar of four units, evenly spaced, on the left side of the runway unless that is impracticable. The simpler APAPI has two units.
Each unit shows red when you are below its own angle and white when you are above it. The change between the colours is sharp, within 3 minutes of arc seen from at least 300 m away. The four units are set at slightly different angles, so as you climb or sink you see them flip one at a time.
Count from the runway outward:
- On or close to slope: two red nearest the runway, two white.
- Slightly high: one red, three white.
- Further high: four white.
- Slightly low: three red, one white.
- Further low: four red.
An APAPI reads the same way with two units. On slope is inner red and outer white. Above is both white and below is both red.
Describe this figure
A side view shows a PAPI beside the runway at the right, sending four beams upward, lettered A to D from the lowest to the highest. Five aircraft hang in the five zones the beams create, and each is paired with a row of four lights. Well above the slope all four lights are white. Slightly high shows three white and one red, with the red nearest the runway, and on slope shows two white and two red. Slightly low shows one white and three red, and well low shows four red. Below the side view, an APAPI of two lights shows both white above the slope, outer white and inner red on slope, and both red below.
The figure is a side view of five aircraft heights on approach, from well above to well below the slope. Each is paired with the four lights you would see: four white, three white and one red, two and two, one white and three red, and four red. An APAPI strip sits alongside.
A PAPI shows two red and two white on or close to the approach slope, with the red units nearest the runway.
The angle itself is not always 3°. The standard drawing uses 3° as an illustration, with the four units set at 2°30′, 2°50′, 3°10′ and 3°30′. The slope falls midway between the second and third units. The actual angle is published for each runway.
Your aircraft's recommended approach speed, flap setting and sink rate on a PAPI slope are in its POH/AFM. Check your aircraft's POH/AFM. This lesson does not replace ATO instruction or the aircraft's POH/AFM.
What does the PAPI protect? It is set so that a pilot seeing one white and three red still clears all objects in the approach area by a safe margin. That protection applies inside the light beam and inside the protection surface defined for it. It does not follow you around the sky. A pilot circling well off the centre line is not covered.
Runway lights
Seen from final, the runway builds up in layers.
- Approach lights, if there are any, white and leading in.
- A green threshold row, perhaps with green wing bars and flashing white threshold identification lights.
- Two white edge rows converging in perspective.
- A yellow edge section in the last 600 m or one-third of the runway, whichever is less.
- A red end row.
The PAPI sits on the left, and blue taxiway edges and green taxiway centre lines show off to the side.
Describe this figure
The picture looks down a lit runway from final approach at night. In the foreground, white approach lights lead in along the centre line, with a crossbar. Then comes the green threshold bar with green wing bars sticking out on both sides. Two rows of white edge lights run away in perspective toward the far end, where they turn yellow. A row of red lights marks the end of the runway. On the left, beside the runway, the PAPI shows two white and two red lights, the on-slope indication.
The figure is a night view from final. It shows white approach lights, the green threshold bar with wing bars, two white edge lines turning yellow toward the far end, a red end bar, and the PAPI on the left.
Threshold and wing bar lights are green and face the approach. Runway end lights are red and face the runway, toward an aircraft rolling along it. When the threshold is at the very end of the runway, one row of fittings can serve both purposes. It looks green from the approach and red from the other direction.
Edge lights are white, but two zones change colour.
- Before a displaced threshold, edge lights show red toward an aircraft on approach and white toward an aircraft rolling the other way, because that area can be used for the roll.
- The last 600 m of the runway, or one-third of its length if that is less, show yellow when seen from the take-off start.
Edge lights run the length of the runway in two rows, spaced at most 60 m apart on an instrument runway and 100 m on a non-instrument runway.
Runway edge lights are fixed variable white, except red before a displaced threshold when seen from the approach, and yellow in the last 600 m or one-third of the runway length, whichever is less, at the far end from where the take-off run starts.
Optional flashing white threshold identification lights, 60 to 120 flashes per minute, make a threshold stand out. They are visible only from the approach direction.
Runway centre line lights, where fitted, use a colour code that counts the runway left.
- White from the threshold until 900 m remain.
- Alternating red and white from 900 m to 300 m remaining.
- All red for the last 300 m.
- On runways shorter than 1 800 m, the alternating section starts at the midpoint of the runway usable for landing.
Describe this figure
The first strip shows the centre line lights of a runway 1 800 m or longer, with the threshold at the left. The lights are white until 900 m remain, then alternate red and white until 300 m remain, then are all red to the far end. Tick marks show 900 m to go and 300 m to go. The second strip shows a runway shorter than 1 800 m. Here the alternating red and white section starts at the midpoint of the runway and the last 300 m is still all red. The second strip is not drawn to the same scale as the first.
The figure is a strip for a long runway: white, then alternating red and white, then red. Tick marks show 900 m and 300 m from the far end, and a second strip shows the short-runway variant.
Touchdown zone lights are pairs of white barrettes beside the centre line for the first 900 m, fitted at the most demanding precision runways. Simple touchdown zone lights are one pair of white lights on each side beyond the last touchdown zone marking. They show where the zone ends, which helps a go-around decision.
Rapid exit indicator lights are yellow lights beside the centre line, in groups of three, two and one at 100 m steps before a rapid exit taxiway. They count down the distance to the exit.
Stopway lights are red and face the runway. Automatic runway status lights are red lights that come on by themselves if the system detects a conflict.
Taxiway, holding and apron lights
On the ground, the pattern flips. Taxiway centre lines are green and taxiway edges are blue. Green means "follow me", blue means "the paved edge is here".
Near a runway the green centre line lights start to alternate green and yellow. That alternating pattern means you are inside the runway's protected area, where your aircraft could affect the instrument landing signals. When you leave a runway, the change to all green marks the edge of that area. A runway vacated sign marks the same boundary where there are no centre line lights (see the signs page, 010-09-05).
"Green and yellow alternating centre lights mean I am near the apron." Wrong. They mean you are close to or within a runway's protected area.
Three kinds of lights guard a runway entrance.
- A stop bar is a row of red lights across the taxiway, at most 3 m apart. A lit stop bar means stop and hold until the lights are switched off. The red bar goes out and the green centre line lights beyond it come on to show you may proceed.
- Intermediate holding position lights are three yellow lights across the taxiway.
- Runway guard lights are flashing yellow lights that warn you that you are about to enter an active runway. They come in two layouts: a pair of lights on each side of the taxiway flashing alternately, or a row across the taxiway.
Describe this figure
A plan view shows a runway across the top and a taxiway running down from it. Blue lights mark the taxiway edges and green lights run along the centre line. Near the runway the centre line lights alternate green and yellow, which marks the runway's protected area. At the holding position a red stop bar crosses the taxiway, and yellow runway guard lights stand on each side, flashing alternately. To the right a second, exit-only taxiway leaves the runway. Its centre line also alternates near the runway, and a red no-entry bar crosses it to stop aircraft from entering the wrong way.
The figure is a plan of a taxiway meeting a runway. It shows blue edge lights, a centre line turning green and yellow near the runway, a red stop bar, yellow runway guard lights, and an exit-only taxiway with a red no-entry bar.
How stop bars are switched and how clearances work is taught on the air traffic control procedures page (010-07-02).
A no-entry bar is different. It is a row of red lights across an exit-only taxiway and it shows you must not enter that taxiway in that direction at all. It is not a "wait for clearance" light.
An aircraft on the manoeuvring area stops and holds at every lit stop bar.
Aprons used at night are floodlit, aimed to keep glare from pilots. At large stands, yellow lights guide you along the lead-in line and red lights mark the stop position. Docking systems at airline stands use green for on the centre line and red for off the centre line and for stop. This is airline-stand equipment, and at most GA aprons guidance comes from markings or a marshaller.
Worked examples
Given: a runway 2 400 m long with centre line lights, measured from the threshold you land over. Method: the alternating red and white section starts 900 m before the far end and the all-red section starts 300 m before the far end. Working: 2 400 m − 900 m = 1 500 m, and 2 400 m − 300 m = 2 100 m. Answer: white until 1 500 m, alternating from 1 500 m to 2 100 m, red from 2 100 m, so the last 300 m is all red.
Given: a PAPI with units set at 2°30′, 2°50′, 3°10′ and 3°30′, as in the illustrated 3° example. Your aircraft is at 2°40′. Method: a unit shows white when you are above its setting and red when you are below. Working: 2°40′ is above 2°30′ and below the other three settings. Answer: 1 white unit and three red, so you are slightly low. The signal tells you to correct, and it still clears obstacles if you are inside the beam.
In the real world
On 7 July 2017 an Airbus A320, C-FKCK (Air Canada 759), was cleared to land at night on runway 28R at San Francisco. The crew lined up with parallel taxiway C, where four airliners were waiting, and overflew them at very low height before going around.
The parallel runway 28L was closed by NOTAM and its lights were off, so the crew took the lit 28R for 28L, and the taxiway for 28R. The flashing closure cross on 28L did not catch their attention. The taxiway had green centre line lights, which the crew recalled seeing, yet it still looked like a runway.
The probable cause was misidentification of the taxiway, due to poor awareness of the closure from the NOTAM review.
Check the NOTAMs, and cross-check what you see. A runway has white edges, a green threshold and a PAPI. A taxiway has blue edges and a green centre line.
Exam traps
"Threshold lights are white" or "green toward the runway." They are green toward the approach. Runway end lights are red toward the runway.
"Taxiway edge lights are green." They are blue. The green lights are the centre line.
"Three white and one red is on slope." That is slightly high. On slope is two red and two white, red nearest the runway.
"One white and three red is unsafe." It is slightly low but still clears obstacles inside the beam. Four red is the real danger state.
"Flashing yellow lights at a runway-holding position mean proceed with caution." They mean a runway is ahead; enter only with a clearance.
Explain it back
You are on final at night and you see four white lights on the left of the runway. Then, a few seconds later, you see three white and one red. Explain in your own words what is happening to your flight path, which light changed first, and what you would do.
Self-check
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On final at night you see the PAPI on the left of the runway showing two red lights nearest the runway and two white lights further out. What does this mean?mcq · easy
Show answer
Two red nearest the runway plus two white is the on-slope picture. One red and three white would be slightly high, three red and one white slightly low, and four red well below the slope.
Reference: CS ADR-DSN.M.645(b)(2)
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On final at night you see a green row of lights across the runway ahead and, at the far end, a red row. Which statement is correct?mcq · medium
Show answer
Threshold lights show green toward aircraft on approach and runway end lights show red toward the runway. The first option reverses the colours. Stop bars are across taxiways, not at runway ends. The third is wrong because the red end lights face the runway, so a pilot rolling along it sees them, not one on final.
Reference: CS ADR-DSN.M.680(e)(1); CS ADR-DSN.M.685(c)(1)
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A runway is 1 500 m long and has centre line lights. How far from the landing threshold does the alternating red and white section of the centre line begin?mcq · medium
Show answer
On a runway shorter than 1 800 m the alternating section starts at the midpoint of the runway usable for landing, so 1 500 m divided by 2 gives 750 m. The 900 m option applies to a long runway, where the alternating section starts 900 m before the end. The 600 m and 1 200 m figures do not come from either rule.
Reference: CS ADR-DSN.M.690(d)(1)
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You are taxiing at night toward a runway holding position when you see a row of red lights across the taxiway ahead of you, lit. What do you do?mcq · medium
Show answer
A lit stop bar means stop and hold until the lights are switched off. The second and third options treat it as advisory, which it is not. The fourth describes a no-entry bar, which also has red lights but is placed on an exit-only taxiway; the question describes an ordinary holding position, so stop and hold is the answer.
Reference: SERA.3210(d)(3); CS ADR-DSN.M.730(b)
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While taxiing away from a runway at night, you notice the green and yellow alternating centre line lights change to all green. What does this tell you?mcq · hard
Show answer
Alternating green and yellow centre line lights show that you are in the protected area near a runway, and the change to all green marks the edge of that area as you leave. They do not mean the apron or a closure, and runway guard lights are separate yellow flashing lights beside or across the taxiway.
Reference: CS ADR-DSN.M.710(c)(2); CS ADR-DSN.M.710(c)(3)
Key concepts
Written with ASD-STE100 writing principles: short sentences, one topic per sentence, active voice, one word for one meaning.
PAPI slope indication
On slope, a PAPI shows two red and two white lights. More red lights mean the aircraft is lower than the slope. A pilot who sees one white and three red lights still clears all objects in the approach area by a safe margin. Rule: CS ADR-DSN.M.645(b)(2)
Threshold and end lights
Threshold lights show green toward the approach. Runway end lights show red toward the runway. At a runway extremity, one row of lights can serve as both. Rule: CS ADR-DSN.M.685(c)(1)
Runway edge lights
Runway edge lights show variable white. The last 600 m or one-third of the runway length, whichever is less, shows yellow at the far end. Edge lights before a displaced threshold show red toward the approach. Rule: CS ADR-DSN.M.675(c)(1)
Taxiway lights
Centre line lights of a taxiway show green. Edge lights of a taxiway show blue. On an exit taxiway, centre line lights alternate green and yellow near the runway. Rule: CS ADR-DSN.M.710(c)(1), (c)(2)
Lights at holding positions
A stop bar is a row of red lights across a taxiway, at a point where traffic stops. Stop and hold at every lit stop bar. Runway guard lights flash yellow at a runway-holding position. Rule: SERA.3210(d)(3) Do not: Cross a lit stop bar.
Runway centre line lights
Centre line lights show variable white from the threshold to 900 m before the runway end. They alternate red and variable white from 900 m to 300 m before the end. The last 300 m before the runway end show red. Rule: CS ADR-DSN.M.690(d)(1)
Aerodrome and identification beacons
An aerodrome beacon flashes 20 to 30 times per minute in total. The EU text says only coloured flashes; the ICAO standard names the colour. At a land aerodrome, the beacon shows white only, or white flashes mixed with green flashes. An identification beacon sends its identification characters in Morse code, in green at a land aerodrome under the ICAO standard. Rule: CS ADR-DSN.M.620(b)(3)(ii)
Flashcards
Print them: A6 landscape cards (PDF, front and back) · 4 cards per A4 landscape sheet (PDF, cut lines) · Key figures deck (PDF, 24 figures)
Print double-sided, flip on the short edge.
010-09-04-01What does a PAPI show on the approach slope?
Two red and two white lights.
010-09-04-02What does a PAPI show when the aircraft is slightly low?
Three red and one white light.
010-09-04-03What does a PAPI show when the aircraft is slightly high?
One red and three white lights.
010-09-04-04How many light units does a PAPI wing bar have?
Four units. An APAPI has two units.
010-09-04-05What does a pilot who sees one white and three red PAPI lights still clear?
All objects in the approach area, by a safe margin.
010-09-04-06Which colour do threshold lights show toward the approach?
Green.
010-09-04-07Which colour do runway end lights show toward the runway?
Red.
010-09-04-08At a runway extremity, what does one shared row of lights show toward the runway?
Red toward the runway. Green toward the approach.
010-09-04-09Which colour do runway edge lights show?
Variable white.
010-09-04-10Which runway edge lights show yellow?
The last 600 m or one-third of the runway length, whichever is less, at the far end.
010-09-04-11Which colour do edge lights show before a displaced threshold, seen from the approach?
Red.
010-09-04-12Which colour do taxiway centre line lights show?
Green.
010-09-04-13Which colour do taxiway edge lights show?
Blue.
010-09-04-14On an exit taxiway near the runway, how do centre line lights alternate?
Green and yellow, alternating.
010-09-04-15What does a lit stop bar tell a pilot to do?
Stop and hold. Do not cross a lit stop bar.
010-09-04-16How far apart must stop bar lights be?
Not more than 3 m apart.
010-09-04-17Which colour and pattern do runway guard lights show?
Yellow, flashing.
010-09-04-18Where do the red and white centre line lights alternate on a runway?
From 900 m to 300 m before the runway end.
010-09-04-19Which colour do the last 300 m of runway centre line lights show?
Red.
010-09-04-20How many flashes per minute does an aerodrome beacon give in total?
20 to 30 flashes per minute.
010-09-04-21Which colours does an aerodrome beacon show at a land aerodrome?
White only, or white mixed with green (the ICAO standard names the colour).
010-09-04-22What does an identification beacon send at a land aerodrome?
Identification characters in Morse code, green at a land aerodrome under the ICAO standard, at 6 to 8 words per minute.
010-09-04-23Where does obstacle clearance for a PAPI apply?
Only within the obstacle protection surface and the lateral limits of the light beam.
Sources
- Easy Access Rules for Aerodromes (Regulation (EU) No 139/2014), including AMC/GM and CS ADR-DSN Issue 7 (Chapters A, M, U), EASA, March 2026.
- Regulation (EU) No 139/2014, Annex IV, ADR.OPS.A.057 (origination of NOTAM), Easy Access Rules for Aerodromes, March 2026.
- Regulation (EU) 2018/1139 (Basic Regulation), Article 2, consolidated text of 2 August 2026 (EUR-Lex).
- Standardised European Rules of the Air (Regulation (EU) No 923/2012), SERA.3210(d)(3) and GM1 SERA.3210(d)(3), SERA Easy Access Rules.
- Easy Access Rules for Air Traffic Management/Air Navigation Services (Regulation (EU) 2017/373), GM2 ATS.TR.210(a)(3)(c), March 2025.
- ICAO Annex 14, Aerodromes, Volume I, Aerodrome Design and Operations, 9th edition (July 2022), consolidated to Amendment 18.
- NTSB Incident Report NTSB/AIR-18/01, Air Canada flight 759, San Francisco, adopted 25 September 2018. https://www.ntsb.gov/investigations/pages/DCA17IA148.aspx
This page is educational. It does not replace instruction at your ATO or your aircraft's POH/AFM. Rules change: check the regulation in force.