Runway Lighting
Runway Centreline Light for Airfield Ground Lighting
Longitudinal visual guidance along the runway centreline
Runway centreline lights provide longitudinal visual guidance along the runway centreline for precision approach and low-visibility runway operations. Precision AGL Solutions supplies centreline lighting selected against runway classification, approach category, colour sequence, optical direction, fixture spacing, series-circuit characteristics and the approved runway lighting layout.
Supplied by Precision AGL Solutions
Product Overview
Runway Centreline Light
What It Does
Runway centreline lights provide longitudinal visual guidance along the runway centreline and form an important component of the visual aids associated with precision approach and low-visibility runway operations.
Unlike runway edge lights, which define the lateral limits of the runway, centreline lights provide visual guidance along the runway's longitudinal axis.
The final fixture configuration should always be based on the approved runway lighting layout and applicable aerodrome requirements.
ICAO Annex 14 requires runway centre line lights on CAT II and CAT III precision approach runways, and on runways intended for take-off with operating minima below an RVR of the order of 400 m. It recommends them on CAT I precision approach runways, particularly where the runway is wider than 50 m. Confirm the clause and edition for the project.
Selected According To
- Runway classification
- Precision approach category
- Runway length
- Runway centreline arrangement
- Required colour sequence
- Optical direction
- Fixture spacing
- Inset installation requirements
- Series-circuit characteristics
- Photometric requirements
- Pavement and housing arrangement
- Project technical specification
Primary Applications
Where Runway Centreline Lights Are Used
Precision approach runwaysLongitudinal guidance for precision approach operations.
Instrument runwaysCentreline visual reference for instrument operations.
Low-visibility operationsVisual guidance where visibility is reduced.
Centreline visual guidancePrimary longitudinal reference along the runway.
Runway rehabilitation projectsReinstatement during runway rehabilitation.
New runway constructionCentreline lighting for new airfield projects.
Runway lighting upgradesModernised AGL systems and upgrades.
CAT I / II / III applicationsCAT I where applicable; CAT II and CAT III systems.
Replacement of inset fixturesReplacement of existing inset centreline fixtures.
Function of Centreline Lighting
The Primary Longitudinal Reference Through the Runway Environment
What the Lights Do
The runway centreline provides the primary longitudinal reference through the runway environment. Centreline lighting supports visual alignment by creating a controlled sequence of light sources along the runway centreline.
Centreline lighting should therefore be evaluated as an integrated photometric and electrical system.
System Effectiveness Depends On
- Fixture spacing
- Light colour
- Optical direction
- Beam distribution
- Light intensity
- Runway geometry
- Fixture alignment
- Pavement installation
- Electrical circuit performance
- Maintenance condition
Inset Configuration
In-Pavement Installation on the Aircraft Movement Path
Inset / In-pavement Installation
Runway centreline lights are generally associated with in-pavement / inset installation because the runway centreline is an aircraft movement path.
The fixture must be installed correctly within the pavement system to maintain optical alignment, mechanical integrity and serviceability.
The complete inset installation should be considered as an assembly, not simply as a light fitting.
A Typical Inset Installation Comprises
- In-pavement light fixture
- Light housing
- Optical assembly
- Lens
- LED / light source
- Mounting hardware
- Sealing arrangement
- Drainage arrangement
- Secondary connection
- Isolating transformer
- Primary circuit connection
Colour Sequence
Do Not Select by the Generic Term “Runway Centreline Light”
Colour Sequence
The colour sequence of runway centreline lighting is a critical technical characteristic. The applicable sequence depends on the runway configuration, runway length and governing aerodrome requirements.
Under ICAO Annex 14, Volume I (Chapter 5, runway centre line lights), the colour changes toward the runway end to give pilots distance-remaining information: white along the main length of the runway, alternating red and white from 900 m to 300 m before the runway end, and red for the last 300 m. On shorter runways the alternating section begins at the runway midpoint. FAA practice quotes the same zones in feet: white until 3,000 ft remain, alternating red and white from 3,000 ft to 1,000 ft, and red for the last 1,000 ft. Confirm the exact clause and edition applicable to the project.
Longitudinal spacing is also a selection input. ICAO Annex 14 spaces centreline lights at approximately 15 m, and allows approximately 30 m only where the serviceability objective can be demonstrated and the runway is used in RVR of 350 m or more. FAA practice is 50 ft (15 m). Confirm the clause and edition for the project.
The optical and colour configuration must match the approved runway lighting design.
Confirm During Product Selection
- Required colour sequence
- Number of colour sections
- Directionality
- Fixture type
- Runway length
- Fixture spacing
- Approach category
- Applicable standard
- Approved runway lighting drawing
Do not select centreline fixtures solely by the generic term “runway centreline light.” Always verify the approved lighting layout and applicable standard before procurement.
Directional Optical Configuration
Correct Orientation Is Critical
Directional Optical Outputs
Centreline lights may be designed with directional optical outputs appropriate to the intended viewing direction. Important optical characteristics include:
- Unidirectional output
- Bidirectional output
- Directional beam
- Beam spread
- Horizontal coverage
- Vertical coverage
- Intensity distribution
- Colour-specific optical output
Why Orientation Matters
An incorrectly oriented centreline fixture can produce inadequate longitudinal guidance even when the fixture is electrically operational.
Optical direction, colour and beam distribution must be confirmed for each fixture position against the approved runway lighting layout.
On a bidirectional fixture, each side must show the sequence colour for its own direction of view, including the red and alternating red/white sections near the runway ends.
Photometric Performance
Centreline Lights Are Precision Optical Devices
| Parameter | Engineering Requirement |
|---|---|
| Light source | LED or approved technology |
| Light colour | Applicable centreline sequence |
| Intensity | Standard / project specific |
| Beam distribution | Manufacturer specific |
| Horizontal coverage | Applicable requirement |
| Vertical coverage | Applicable requirement |
| Optical direction | Runway direction specific |
| Colour coordinates | Applicable standard |
| Intensity steps | Where applicable |
| Alignment | Critical |
| Photometric verification | Project dependent |
Photometric compliance should be established through the applicable inspection or measurement process rather than by visual observation alone.
LED Light Source
LED Technology
Potential Advantages
- Long operating life
- Reduced lamp replacement
- Stable light output
- Controlled optical distribution
- Reduced maintenance requirements
- Improved energy efficiency
- Consistent colour performance
- Compatibility with modern AGL monitoring systems
Compliance Is Not Automatic
Modern runway centreline fixtures may use LED technology. However, LED technology is only one component of the complete lighting system.
The fixture optics, electrical system, colour performance and photometric output must all satisfy the applicable requirements.
Electrical Characteristics
AGL Series Circuit Arrangement
Constant Current Regulator → Primary AGL Cable → Isolating Transformer → Secondary Cable → Inset Runway Centreline Light
Parameters to Verify
- Rated series-circuit current
- Isolating transformer rating
- Secondary electrical characteristics
- Power consumption
- Connector arrangement
- Cable interface
- Intensity control
- Circuit monitoring
- Insulation requirements
Why the Whole Chain Matters
Fixtures installed within an AGL series circuit must be electrically compatible with the complete circuit. The centreline fixture should be selected together with its associated isolating transformer and circuit configuration. Incorrect electrical selection can result in:
- Incorrect light intensity
- Improper intensity control
- Electrical stress
- Circuit instability
- Transformer overheating
- Premature fixture failure
- Monitoring abnormalities
The complete circuit should be evaluated during design and commissioning. On precision approach runways, centreline circuits are normally arranged so that a single circuit failure does not leave an ineffective pattern (for example by interleaving fixtures across circuits); confirm against ICAO Annex 14 Chapter 8 and Doc 9157 Part 5.
Construction & Environment
Mechanical Construction and Environmental Performance
Mechanical Construction
Depending on the manufacturer's configuration, the centreline fixture may include:
- High-strength fixture body
- Inset housing
- Optical lens
- LED / light-source module
- Reflector or optical assembly
- Gasket system
- Fasteners
- Secondary cable interface
- Drainage provisions
- Pavement mounting system
Exact construction, materials and dimensions should be verified against the manufacturer's technical documentation.
Environmental Performance
Runway centreline fixtures operate in a demanding environment. Evaluate the product for:
- Water ingress
- Dust
- Humidity
- Temperature variation
- UV exposure
- Corrosion
- Vibration
- Mechanical impact
- Pavement loading
- Aircraft tyre loading
- Cleaning chemicals
For inset fixtures, give particular attention to water ingress + drainage + sealing + pavement interface + mechanical loading.
Pavement & Inset Installation
Installed Within a Demanding Mechanical and Environmental Environment
Fixture Seating
The fixture should be correctly seated within the housing and pavement interface.
Alignment
The optical axis must correspond with the approved runway centreline and required beam direction.
Level
The fixture installation should satisfy the approved pavement and fixture installation requirements.
Drainage
Water accumulation around the fixture / housing should be prevented through the approved drainage arrangement.
Sealing
Gaskets and sealing components should be installed correctly to reduce moisture ingress.
Cable Connection
Secondary cables and connectors should be installed without mechanical damage or excessive bending.
Installation Depth & Fixing
Take Dimensions From the Approved Installation Drawing
Technical Submission Should Establish
- Fixture dimensions
- Housing dimensions
- Installation depth
- Pavement cut-out requirements
- Mounting arrangement
- Fastener specification
- Housing depth
- Cable routing
- Drainage arrangement
- Required installation tools
Why It Matters
Installation depth is an important product-selection parameter for inset centreline fixtures.
The exact dimensions should always be taken from the approved manufacturer's installation drawing, not estimated from a catalogue photograph.
Installation Configuration
Inset Centreline Light — Key Characteristics
| Feature | Inset Centreline Light |
|---|---|
| Installation | In-pavement |
| Aircraft movement area | Suitable where specified |
| Optical alignment | Critical |
| Mechanical loading | High |
| Pavement interface | Critical |
| Drainage | Critical |
| Sealing | Critical |
| Maintenance | Requires fixture / housing access |
| Mounting | Inset housing |
| Cable interface | Secondary circuit connection |
For runway centreline applications, the installation configuration is normally driven by the runway operational and pavement requirements. The approved project design should determine the exact fixture and housing arrangement.
Commissioning & Testing
Verify as Part of AGL Commissioning
Visual Inspection
- Fixture condition
- Lens condition
- Fixture seating
- Housing condition
- Alignment
- Pavement interface
- Fasteners
- Gaskets
- Drainage
- Connector condition
- Evidence of moisture
Electrical Tests
Depending on the approved test procedure:
- Circuit continuity
- Insulation resistance
- Transformer verification
- Secondary connection
- Series-circuit current
- CCR operation
- Intensity-step operation
- Monitoring operation where applicable
Photometric Verification
Where required:
- Verify colour
- Verify intensity
- Verify beam distribution
- Verify optical direction
- Verify centreline alignment
- Verify colour sequence
- Confirm photometric performance
A centreline light that is electrically operational is not automatically photometrically compliant.
Inspection & Maintenance
Inspect Both the Optical System and the Pavement Installation
Optical
- Lens cleanliness
- Lens damage
- Light output
- Colour
- Beam direction
- Optical contamination
Mechanical
- Fixture seating
- Housing
- Fasteners
- Gaskets
- Pavement condition
- Fixture damage
Electrical
- Transformer
- Secondary cable
- Connector
- Circuit current
- Insulation
- Moisture evidence
Inset Housing
- Water accumulation
- Drainage blockage
- Corrosion
- Damaged seals
- Housing deformation
- Loose mounting
- Contamination
Common Failure Modes
Typical Centreline-Light Problems
| Symptom | Possible Causes |
|---|---|
| Centreline light OFF | Open series circuit; failed light source; isolating transformer failure; connector failure; secondary cable fault; internal fixture failure |
| Low light output | Incorrect CCR intensity; optical contamination; LED degradation; damaged optical component; incorrect electrical characteristics; fixture alignment issue |
| Intermittent operation | Loose connection; moisture ingress; connector deterioration; transformer connection problem; internal fixture fault |
| Incorrect colour | Incorrect fixture type; incorrect optical configuration; light-source problem; optical contamination; incorrect replacement component |
| Incorrect beam direction | Fixture installed in incorrect orientation; optical assembly incorrectly configured; fixture movement; installation error; incorrect replacement fixture |
Engineering Troubleshooting Sequence
A Practical Diagnostic Sequence
CCRVerify output
Primary series circuitCheck circuit
Isolating transformerCheck transformer
Secondary cableCheck cable
ConnectorCheck connector
Inset centreline fixtureCheck fixture
Light sourceInspect
Optical systemInspect
Photometric verificationConfirm output
This sequence helps identify whether the problem is electrical, mechanical, optical or installation-related.
Product Selection Checklist
Before Ordering, Confirm
- Airport / project
- Runway identification
- Runway length
- Runway classification
- Approach category
- Centreline lighting requirement
- Fixture spacing
- Colour sequence
- Optical direction
- Beam distribution
- Intensity requirement
- Intensity steps
- LED / approved light source
- Series-circuit current
- Isolating transformer
- Connector type
- Housing type
- Installation depth
- Pavement cut-out
- Mounting details
- Drainage arrangement
- Environmental requirements
- Applicable standard
- Manufacturer TDS
- Photometric documentation
- Compliance / type-test documentation
- Project approval requirements
Technical Submittal
Technical Documents to Request
For technical evaluation and procurement, request:
- Product datasheet
- Technical specification
- Photometric data
- Beam distribution diagram
- Colour information
- Colour sequence information
- Electrical specification
- Power consumption
- Operating current
- Isolating transformer requirement
- Connector details
- Housing drawing
- Fixture dimensions
- Installation depth
- Pavement cut-out details
- Mounting details
- Weight
- Material specification
- Environmental rating
- Installation manual
- Maintenance manual
- Compliance certificates
- Type-test reports
- Warranty information
Safety
Electrical Safety — Isolation and Lock-Out
WARNING — never open a live series circuit. An open series circuit driven by a constant-current regulator can produce dangerously high voltage. Opening, cutting or disconnecting any part of an energised circuit can cause serious injury or death and damage equipment.
- De-energise the circuit at the regulator and apply the site lock-out / tag-out (LOTO) procedure before any work
- Where the circuit must be isolated or shorted, use the series circuit cut-out switch or approved isolation device — not an improvised bypass
- Verify the circuit is de-energised and the output is isolated before touching conductors, connectors, splices, transformers or fixtures
- Do not disconnect or reconnect a fixture's secondary connector while the series circuit is energised: an open secondary on a series isolating transformer can develop hazardous voltage and damage the transformer
- Work on the movement area only under the airport's permit-to-work system, with the runway or taxiway closed as required, using qualified personnel and the manufacturer's instructions
- Follow the applicable national electrical safety regulations and site procedures
Standards & References
Governing Standards
Select, install and test in accordance with the applicable edition of the governing aerodrome standards and approved project specification.
- ICAO Annex 14, Volume I — Chapter 5 (runway centre line lights), Appendix 1 (colours) and Appendix 2 (light characteristics), Chapter 8 (electrical systems) and Chapter 10 (maintenance, including serviceability targets for CAT II/III)
- ICAO Aerodrome Design Manual (Doc 9157) — Part 4 (Visual Aids) and Part 5 (Electrical Systems)
- FAA AC 150/5340-30J — Design and Installation Details for Airport Visual Aids (centreline layout, spacing and colour)
- FAA AC 150/5345-46F — Specification for Runway, Taxiway, Heliport, and Vertiport Light Fixtures (L-850A runway centreline fixture)
- DGCA India requirements and applicable Indian Standards, where applicable
- Airport-specific technical specifications, approved runway lighting layout and AGL drawings
- Manufacturer installation instructions
See the ICAO Annex 14 Guide and FAA AGL Guide for background.
Important: Verify the applicable standard edition and project specification before procurement.
FAQ
Runway Centreline Light — Frequently Asked Questions
What does a runway centreline light do?
Runway centreline lights provide longitudinal visual guidance along the runway centreline and are an important part of the visual aids for precision approach and low-visibility runway operations. Unlike runway edge lights, which define the lateral limits of the runway, they give a visual reference along the runway's longitudinal axis.
When does ICAO require runway centre line lights?
ICAO Annex 14 requires runway centre line lights on CAT II and CAT III precision approach runways, and on runways intended for take-off with operating minima below an RVR of the order of 400 m. They are recommended on CAT I precision approach runways, particularly where the runway is wider than 50 m. Confirm the clause and edition for your project.
What is the colour sequence of runway centreline lights?
Under ICAO Annex 14, Volume I, the lights are white along the main length of the runway, alternating red and white from 900 m to 300 m before the runway end, and red for the last 300 m; on shorter runways the alternating section begins at the runway midpoint. FAA practice quotes the same zones in feet: white until 3,000 ft remain, alternating red and white from 3,000 ft to 1,000 ft, and red for the last 1,000 ft. Confirm the exact clause and edition applicable to the project.
What spacing is used for runway centreline lights?
ICAO Annex 14 spaces centreline lights at approximately 15 m, and allows approximately 30 m only where the serviceability objective can be demonstrated and the runway is used in RVR of 350 m or more. FAA practice is 50 ft (15 m). Confirm the clause and edition for the project.
Why are runway centreline lights installed in the pavement?
The runway centreline is an aircraft movement path, so centreline lights are generally inset (in-pavement) fixtures. The complete installation should be treated as an assembly: fixture, housing, optical assembly, sealing and drainage arrangement, secondary connection, isolating transformer and primary circuit connection. Correct installation in the pavement maintains optical alignment, mechanical integrity and serviceability.
What is the difference between unidirectional and bidirectional centreline lights?
Centreline lights may have unidirectional or bidirectional optical output, appropriate to the intended viewing direction. On a bidirectional fixture, each side must show the sequence colour for its own direction of view, including the red and alternating red/white sections near the runway ends. An incorrectly oriented fixture can give inadequate longitudinal guidance even when it is electrically operational.
How are runway centreline lights powered?
They are fed from the AGL series circuit: constant current regulator, primary AGL cable, isolating transformer, secondary cable, then the inset centreline light. The fixture should be selected together with its isolating transformer and circuit configuration. On precision approach runways, centreline circuits are normally arranged so that a single circuit failure does not leave an ineffective pattern, for example by interleaving fixtures across circuits; confirm against ICAO Annex 14 Chapter 8 and Doc 9157 Part 5.
Is a centreline light that is switched on automatically compliant?
No. A centreline light that is electrically operational is not automatically photometrically compliant. Colour, intensity, beam distribution, optical direction, centreline alignment and colour sequence should be verified through the applicable inspection or measurement process rather than by visual observation alone.
What are the common faults in runway centreline lights?
Typical symptoms are a light that is off (open series circuit, failed light source, isolating transformer, connector or secondary cable fault), low light output, intermittent operation (loose connection or moisture ingress), incorrect colour and incorrect beam direction. Troubleshoot in sequence: CCR output, primary series circuit, isolating transformer, secondary cable, connector, inset fixture, light source and optical system, then confirm output photometrically. See the electrical safety warning before working on any circuit.
Which standards apply to runway centreline lights?
Relevant references include ICAO Annex 14, Volume I (Chapter 5 for runway centre line lights, Appendix 1 for colours, Appendix 2 for light characteristics, Chapter 8 for electrical systems and Chapter 10 for maintenance), ICAO Doc 9157 Parts 4 and 5, FAA AC 150/5340-30J for layout, spacing and colour, and FAA AC 150/5345-46F for the L-850A runway centreline fixture. Indian projects should also check DGCA requirements and the airport-specific specification. Verify the applicable edition before procurement.
What should be confirmed and requested before ordering centreline lights?
Confirm the runway length and classification, approach category, colour sequence, fixture spacing, optical direction, beam distribution, intensity steps, series-circuit current, isolating transformer, connector type, housing type, installation depth and pavement cut-out. Request the product datasheet, photometric data, colour sequence information, housing drawing, installation depth details, installation and maintenance manuals, compliance certificates and type-test reports.
Why Precision AGL Solutions
A Complete-System Approach
Precision AGL Solutions considers runway centreline lighting as part of the complete Airfield Ground Lighting system. Our technical approach connects:
Runway Geometry → Centreline Layout → Fixture → Optics → Housing → Transformer → Connector → Series Circuit → CCR → Photometry → Maintenance
This system-level approach supports technically appropriate product selection and helps identify compatibility issues before installation.
Procurement Information for Indian Projects
Indian public tenders commonly ask for the documents below. State which ones your tender requires when you send the enquiry, so they are covered in the quotation.
- Manufacturer / OEM authorisation
- Country of origin and local-content declaration (for Make in India purchase preference)
- Type-test and routine-test certificates, and the FAA / ICAO / IEC compliance documents named in the specification
- Datasheets, drawings and installation instructions
- Warranty, delivery period and spares support
- GeM catalogue or tender-portal requirements, where applicable
Need the Right Runway Centreline Light?
Have a runway lighting requirement? Send us your runway configuration, runway length, approach category, existing centreline arrangement, approved lighting layout, BOQ, technical specification, fixture quantity, existing fixture details, series-circuit information and housing details where available. We can review it and identify the appropriate runway centreline lighting configuration for the project.
- Emailprecisionaglsolutions@gmail.com
- Websiterahulsharmaagl.in
- LinkedInPrecision AGL Solutions
- Phone+91 98214 96412
Engineering Note
Runway centreline lights are safety-critical visual aids and require careful coordination between runway geometry, colour sequence, optical performance, fixture spacing, pavement installation and AGL electrical circuits.
Product selection should therefore not be based only on fixture appearance or nominal electrical rating. The complete photometric, mechanical and electrical configuration should be reviewed against the approved runway design and applicable aerodrome requirements before technical approval and procurement.
Product Disclaimer
Product availability, configuration, dimensions, electrical characteristics, photometric performance, certifications and compliance status depend on the selected manufacturer and project specification. The technical values published on this page should not be treated as a substitute for the manufacturer's current approved Technical Data Sheet.
Final selection shall be based on the approved project specification, applicable aviation standards, authority requirements, manufacturer documentation and site conditions. Use of this page is also subject to the Legal Notice, Disclaimer & Terms of Use.
Standards and editions referenced on this site are listed on the Standards Reference page.