Runway End Light VS Threshold/End Combination Light
One Function vs Two Functions in One Fixture — a runway end light provides a dedicated red indication of the runway's physical termination, while a threshold/end combination light is a bidirectional fixture that shows green threshold indication in one direction and red runway-end indication in the opposite direction. On a two-way runway, the physical extremity is a threshold for one direction and an end for the other, so the bidirectional combination fixture is the standard, default configuration at most runway extremities — not a special case reserved for shorter runways.
Combination Is the Norm; Dedicated End-Only Is the Exception
Per FAA/ICAO guidance, threshold and runway-end lights are usually the same bidirectional fixture at each end of a two-way runway — green outward to landing traffic, red toward the runway to departing/rollout traffic — precisely because almost every runway end simultaneously functions as the opposite direction's threshold. A genuinely single-function, red-only runway end light is the exception, not the everyday case: it applies where the light row at that physical extremity has no opposing threshold role to play — for example, a one-way-only runway, or a location beyond a permanently displaced threshold or past a stopway/blast pad where the declared runway end does not coincide with a landing threshold.
At a Glance
| Feature | Runway End Light | Threshold/End Combination Light |
|---|---|---|
| Main purpose | Identifies the runway end | Identifies threshold in one direction + runway end in the opposite direction |
| Light type | Dedicated end indication | Bidirectional combination fixture |
| Typical colour | Red toward the runway | Green one direction / red the opposite direction |
| Directionality | Primarily one direction | Two directions |
| Installation point | At runway end | At the threshold/end location |
| Aircraft approaching threshold | Not normally the threshold indication | Green indication |
| Aircraft moving toward runway end | Red | Red indication |
| Main advantage | Simple, dedicated function | Two functions from one fixture |
| Typical application | One-way runways, or a light row with no opposing threshold role (e.g. beyond a displaced threshold) | Standard configuration at most two-way runway extremities |
One Direction vs Two Directions From the Same Point
The fundamental difference is how many optical directions the fixture serves. A runway end light is built around a single function: telling an aircraft moving toward that extremity from within the runway that this is where the runway physically terminates. A threshold/end combination light packs two functions into one physical installation — green threshold indication for an aircraft approaching to land, and red end indication for an aircraft viewing it from the runway side.
(dedicated, red)
(green + red)
What Each Light Is
Runway End Light
A dedicated fixture identifying the end of the runway. Viewed from the runway toward the end, it shows red, telling the pilot this is where the runway physically terminates.
Tells the pilot
- This is the end of the runway
- Runway pavement terminates here
- Clear stop/end warning
Threshold/End Combination Light
A bidirectional fixture with two optical outputs. From the approach side it shows green as the threshold; from the opposite, runway-side direction it shows red as the runway end — two functions from one installation point.
Tells the pilot
- Green: this is the threshold, landing may begin here
- Red: this is the runway end, seen from the opposite direction
- One fixture, two directional roles
One Colour vs Two Colours
A runway end light is built to produce one colour toward one direction. A combination fixture is built to produce two different colours toward two different directions from the same physical location — that's the whole point of calling it a "combination" light rather than just an end light.
Easy memory: end light = red toward the end, full stop. Combination light = green toward the threshold, red toward the end — the colour depends entirely on which side you're viewing it from.
Why a Combination Fixture Is Used
The runway end for one direction is the threshold for the opposite direction: on a two-way runway, the physical extremity that is a runway end for aircraft landing from one side is the landing threshold for aircraft approaching from the other side. A bidirectional threshold/end fixture is the logical way to serve both roles from a single installation.
What Each Light Answers
Runway End Light
Answers: "Where does the runway physically terminate?" A single, dedicated indication with no threshold role attached.
Threshold/End Combination Light
Answers both: "Where does landing begin?" (green, approach side) and "Where does the runway terminate?" (red, runway side) — from the same physical fixture line.
Don't Confuse This With Threshold + Wing Bar
These are different concepts entirely. A wing bar extends threshold lighting laterally, widening the visual threshold indication on either side of the runway centreline — it doesn't add a second, opposite-direction colour. A threshold/end combination light instead provides different colours in opposite viewing directions from the same installation point. One extends the threshold sideways; the other gives the threshold fixture a second job facing the other way.
Why Combination Fixtures Are Chosen
Because a combination fixture is the standard choice at most two-way runway extremities, a genuinely dedicated, single-function end light is reserved for locations where there is no opposing threshold role to serve — for example a one-way runway or a light row beyond a displaced threshold or stopway. Where a combination fixture is used, it performs two functions instead of one:
- Reduced number of separate fixtures
- Simplified installation at the threshold/end
- Reduced civil work in some installations
- Cleaner threshold/end lighting arrangement
Still has to perform: whichever fixture type is used, it must still satisfy the required photometric performance, colour, beam orientation, visibility, reliability, environmental and electrical requirements for both directions it serves.
Runway End Light vs Threshold/End Combination
| Parameter | Runway End Light | Threshold/End Combination |
|---|---|---|
| Optical outputs | Primarily end indication | Threshold + end |
| Direction | One required direction | Two directions |
| Green output | Not the primary function | Yes |
| Red output | Yes | Yes |
| Fixture complexity | Lower | Higher |
| Installation | Dedicated | Combined |
| Maintenance | Simple | Slightly more complex |
| Fixture count on site | Separate fixture per function | Reduced fixture count |
| Typical use | One-way runways or a location with no opposing threshold role | Standard installation at most two-way runway extremities |
Engineering Specification Note
For project specifications, don't specify only "combination light." Specify the intended function — for example: a bidirectional threshold/end light fixture, providing green threshold indication in the approach direction and red runway-end indication in the opposite direction, complying with the applicable ICAO/FAA requirements. The exact fixture type and photometric characteristics should be selected according to the runway classification and applicable aerodrome lighting standard.
Common AGL Terminology Confusion
No — the fixture is directional/bidirectional. Each colour is optically directed toward its own viewing direction, not shown together toward a single direction.
A wing bar widens threshold indication laterally in one direction. A combination light instead adds a second, opposite-direction colour and function — a different concept entirely.
Not necessarily. Where the same physical extremity serves as both a threshold and an end for opposite runway directions, a single bidirectional combination fixture can serve both roles.
Runway End Light vs Threshold/End Combination Light
A runway end light is a single-function fixture; a threshold/end combination light is a two-function fixture built for the same installation point. The choice comes down to whether that point needs a dedicated end indication only, or needs to serve as a threshold in one direction and an end in the other.
Runway end lighting gives a simple, dedicated stop/termination reference. Threshold/end combination lighting saves fixtures by giving that same physical location two directional meanings.
Easy memory: End light = red → end. Combination light = green ↔ red, with green toward the threshold and red toward the runway end.
Engineering & Expert Notes
Verify Orientation of Each Colour
OrientationCombination units show different colours in different directions.
Check Both Colours
ColourVerify each.
Record the Type at Each Position
RecordsKeep registers current.
Check From Both Directions
InspectionView from each side.
Frequently Asked Questions
A runway end light is a dedicated single-function fixture showing red toward the runway end. A threshold/end combination light is a bidirectional fixture that shows green toward the threshold in one direction and red toward the runway end in the opposite direction.
No. The fixture is directional — green optics face the approach side and red optics face the runway side, so each direction sees only the colour meant for it.
Because on a two-way runway, the same physical extremity is a threshold for one direction and an end for the other, a single bidirectional fixture is the standard way to serve both roles — it's the default choice, not just an optional efficiency measure, and it also reduces fixture count and simplifies installation compared to installing two separate unidirectional fixtures.
No. A wing bar extends threshold lighting laterally in the same direction. A combination light provides different colours in opposite viewing directions from the same fixture — a different function.
Specify the intended function explicitly — a bidirectional fixture providing green threshold indication on approach and red runway-end indication in the opposite direction, complying with the applicable ICAO/FAA requirements — rather than just writing "combination light."
Yes, for both directions it serves — photometric performance, colour, beam orientation, visibility, reliability, environmental and electrical requirements all apply to each optical output.
Governing Documents
For an actual project design, always verify the current edition of the applicable documents.
ICAO Annex 14, Volume I
Aerodrome Design and Operations — runway end and threshold lighting colour, siting, intensity and directional/bidirectional requirements.
FAA AC 150/5340-30
Design and Installation Details for Airport Visual Aids — threshold/end lighting configuration, installation, photometric requirements and electrical systems.
DGCA / AAI Requirements
For Indian airport projects, also verify applicable DGCA requirements, AAI requirements, airport-specific technical specifications, project drawings and contract specifications.
Final Engineering Note
Do not design a threshold/end lighting arrangement from a generic web diagram. The final installation drawing should always be developed from the current governing standard, approved airport design and project-specific requirements.
End light = dedicated, red, one direction. Combination light = bidirectional, green toward threshold, red toward end. Choose based on whether the location needs one function or two.
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