TAXIWAY LIGHTING COLOUR MAP
| Lighting system | Colour | Basic meaning |
|---|---|---|
| Taxiway Edge | Blue | Defines taxiway edge |
| Taxiway Centreline | Green | Provides taxiway guidance |
| Lead-On / Lead-Off | Green and Yellow | Indicates runway-environment transition |
| Stop Bar | Red | Indicates stopping position |
| Runway Guard Lights | Flashing Yellow | Identifies runway holding position |
| Runway Entrance Lights (REL) | Red | Indicates runway traffic or approach activity in applicable FAA RWSL systems |
| Intermediate Holding Position Lights | Steady Yellow | Marks a holding position at a taxiway intersection (ICAO) |
FAA guidance (AIM Chapter 2, Section 1; AC 150/5340-30J) confirms blue taxiway-edge lighting, green taxiway-centreline lighting, alternating green/yellow lead-on and lead-off lighting, and flashing-yellow runway guard lights in the applicable configurations.
TAXIWAY EDGE LIGHTS
Taxiway edge lights outline the edges of taxiways and help pilots identify the lateral limits of the taxiway route. Their primary purpose is visual identification of the taxiway edge. They are blue and normally omnidirectional, so do not confuse them with the white runway edge lights.
Exam memory
- Taxiway Edge = BLUE
- Blue → Taxiway Boundary
TAXIWAY CENTRELINE LIGHTS
Centreline lights provide visual guidance along the taxiway route, helping pilots follow the intended movement path between different areas of the aerodrome.
Exam memory
- Taxiway Centreline = GREEN
- Green → Taxiway Guidance
LEAD-OFF LIGHTS
Lead-off lights provide visual guidance for aircraft exiting a runway onto a taxiway. FAA guidance (AIM Chapter 2, Section 1) uses alternating green and yellow lights beginning with green, extending from the runway centreline to one light position beyond the runway holding position or ILS critical-area holding position.
Think
- Leaving the runway → Lead-Off
- Lead-Off = Runway → Taxiway
LEAD-ON LIGHTS
Lead-on lights provide visual guidance for aircraft moving from a taxiway toward the runway. FAA guidance describes the applicable system using the same alternating green and yellow pattern as lead-off lights, to warn pilots and vehicle drivers that they are within the runway environment or ILS critical area. The fixtures are bidirectional: one side shows the lead-on function and the other the lead-off function, so any fixture that shows yellow for lead-off also shows yellow for lead-on.
Think
- Going toward the runway → Lead-On
- Lead-On = Taxiway → Runway
STOP BARS
Stop bars use red lights to identify a stopping position, giving a clear visual indication that an aircraft is required to stop at the designated holding position. Stop bars are normally switched by ATC, and where centreline lead-on lights are provided they are interlocked so that STOP and PROCEED are never shown together. ICAO Annex 14 calls for stop bars at runway-holding positions on runways used in RVR below 550 m (see Note 17).
Exam memory
- STOP BAR = RED
- Stop bar lit = do not cross. Cross only when the bar is switched off; if a lit bar and a crossing clearance conflict, stop and query ATC.
RUNWAY GUARD LIGHTS
Runway guard lights help identify a runway holding position. FAA guidance specifies flashing yellow lights, which flash alternately and may be provided in elevated or in-pavement arrangements. In the usual layouts, Configuration A is a pair of elevated lights on each side of the taxiway, and Configuration B is a row of in-pavement lights across it. Guard lights warn that a runway is ahead; unlike a stop bar they do not by themselves order the aircraft to stop. Where RVR is below 550 m and no stop bar is installed, ICAO requires them at the intersection.
Exam memory
- Runway Guard = Flashing Yellow
- Runway Guard → Runway Holding Position
- The key distinction: flashing yellow = runway guard, not red
RUNWAY ENTRANCE LIGHTS (REL)
REL = Runway Entrance Lights. They form part of the FAA Runway Status Lights (RWSL) system. FAA describes RELs as red in-pavement fixtures arranged along the taxiway centreline from the holding position to the runway edge. When activated, they indicate that it is unsafe to enter or cross the runway because of runway traffic or an aircraft on final approach. RELs are driven automatically by surveillance data, not switched by ATC, and the FAA instruction to pilots is never to cross illuminated red lights. RWSL is an FAA system, not an ICAO standard.
Easy memory
- REL → Red → Runway Entry Warning
INTERMEDIATE HOLDING POSITION LIGHTS
ICAO intermediate holding position lights are at least three steady yellow lights placed symmetrically about the taxiway centreline. They mark a holding position at a taxiway intersection, where aircraft should give way unless ATC clears them. FAA flashing-yellow runway guard lights replaced the older steady-yellow clearance bars at runway holding positions, so do not mix the two.
LEAD-ON VS LEAD-OFF
| System | Aircraft movement | Easy memory |
|---|---|---|
| Lead-Off | Runway → Taxiway | Leaving runway |
| Lead-On | Taxiway → Runway | Going toward runway |
Remember
- Lead-Off = Leaving
- Lead-On = Going On to the runway
The exact installation arrangement should always be understood in relation to the applicable lighting system and airport configuration.
STOP BAR VS RUNWAY GUARD VS REL
| System | Colour / indication | Primary function |
|---|---|---|
| Stop Bar | Red | Indicates stopping position |
| Runway Guard Lights | Flashing Yellow | Identifies runway holding position |
| REL | Red | Indicates runway traffic / approach activity in applicable FAA RWSL systems |
Exam memory
- Red Stop Bar = Stop
- Flashing Yellow Runway Guard = Holding Position
- Red REL = Runway Entrance Lights
TAXIWAY LIGHTING QUICK REVISION TABLE
| System | Main function | Key colour |
|---|---|---|
| Taxiway Edge | Defines taxiway edges | Blue |
| Taxiway Centreline | Provides taxiway route guidance | Green |
| Lead-Off | Guides aircraft leaving runway | Green / Yellow |
| Lead-On | Guides aircraft toward runway | Green / Yellow |
| Stop Bar | Identifies stopping position | Red |
| Runway Guard Lights | Identifies runway holding position | Flashing Yellow |
| REL | Runway traffic / approach activity (FAA RWSL) | Red |
Key points for exams
- Blue = Taxiway Edge
- Green = Taxiway Centreline
- Red = Stop Bar
- Flashing Yellow = Runway Guard
- Green/Yellow = Lead-On / Lead-Off in applicable FAA configurations
- REL = Runway Entrance Lights; Red REL in FAA RWSL
- Lead-Off = Leaving the runway
- Lead-On = Going toward the runway
TAXIWAY REVISION QUESTIONS
1. What colour is a standard taxiway edge light?
Blue
2. What colour is the taxiway centreline?
Green
3. What colour is a stop bar?
Red
4. What colour are runway guard lights?
Flashing Yellow
5. What colours are associated with lead-on/lead-off lighting in FAA guidance?
Alternating Green and Yellow
6. What does REL stand for?
Runway Entrance Lights
7. What colour are RELs in the FAA Runway Status Lights system?
Red
8. What is the difference between lead-on and lead-off lighting?
Lead-off provides guidance when leaving the runway, while lead-on provides guidance when moving toward the runway from a taxiway.
9. What are the two runway guard light configurations?
Configuration A: a pair of elevated flashing yellow lights on each side of the taxiway. Configuration B: a row of in-pavement flashing yellow lights across the taxiway.
10. What should a pilot do when RELs are illuminated?
Never cross the illuminated red lights; it is unsafe to enter or cross the runway. Stop and contact ATC.
FINAL STUDY TAKEAWAY
Do not memorise taxiway lighting colours without understanding their purpose. Study each system through Location → Colour → Function → Operational Meaning.
| Colour | Meaning |
|---|---|
| Blue | Taxiway Edge |
| Green | Taxiway Centreline |
| Green/Yellow | Lead-On / Lead-Off |
| Red | Stop Bar |
| Flashing Yellow | Runway Guard |
| Red | REL in applicable FAA RWSL systems |
A strong AGL student should identify not only the colour, but also the location, movement relationship, operational purpose and applicable system.
The key question is not “What colour is this light?” It is “What does this light communicate to the pilot, where is it used, and what is its operational purpose?”
ENGINEERING & EXPERT NOTES
Do Not Confuse the Control Layers
PrincipleStop bars command; guard lights warn; entrance lights respond to traffic. Understand each function before testing it.
Test Control, Status and Light Together
IntegrationA lit bar is not enough. Verify command, indication and field state.
Check Colour and Pattern
ColourBlue edge, green centreline and the transition lights each have their own checks.
Update Records After Layout Changes
RecordsKeep drawings and control configuration aligned with the field.
REFERENCES & FURTHER READING
These notes are a study aid. Verify details against the primary sources below.
| # | Source | Use it for |
|---|---|---|
| 1 | ICAO Annex 14, Volume I – Aerodrome Design and Operations | Chapter 5 (Visual Aids for Navigation): taxiway centre line, taxiway edge, stop bar and runway guard light provisions. |
| 2 | ICAO Doc 9157 – Aerodrome Design Manual | Part 4 (Visual Aids): taxiway lighting layout and stop bar guidance. |
| 3 | FAA AC 150/5340-30J – Design and Installation Details for Airport Visual Aids | FAA taxiway edge, centreline, lead-on/lead-off, stop bar and runway guard light installation details. |
| 4 | FAA Aeronautical Information Manual (AIM) – Chapter 2, Section 1: Airport Lighting Aids | FAA descriptions of taxiway lighting colours, runway guard lights and Runway Status Lights (RWSL/REL). |
| 5 | FAA AC 150/5345-46F – Specification for Runway, Taxiway, Heliport, and Vertiport Light Fixtures | Fixture specifications for taxiway lights (46F, issued 30 Sep 2024). |
| 6 | FAA AC 150/5340-26C – Maintenance of Airport Visual Aid Facilities | Maintenance methodology for stop bars, runway guard lights and Runway Status Lights. |
| 7 | AAI AIP India / eAIP and DGCA CAR Section 4, Series B, Part I – Aerodrome Standards | Indian aerodrome practice; check the applicable AIP entry and airport specification. |
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