Airport Approach Lighting Systems Design, Components, Installation & Testing
CAT I, CAT II and CAT III configurations, light units, flashers, masts and frangible structures, wiring, aiming, installation, testing, maintenance and approach lighting test reports.
What Is an Airport Approach Lighting System?
An Approach Lighting System (ALS) is a pattern of fixed and, where specified, flashing lights extending from the runway threshold into the approach area. It helps pilots move from instrument flight to visual flight for landing. Its geometry, colour, intensity, alignment and pattern give visual references for runway alignment, roll guidance, height perception and limited distance-to-go information.
ICAO treats approach lighting as part of the visual aids required for different runway types and operating conditions. The framework is Annex 14 Volume I (9th Edition, July 2022, with Amendment 18), and the Aerodrome Design Manual Part 4 is the principal design guidance.
Engineer it as one system
Approach Lighting Configuration Explorer
Switch between configurations to see the layout and what to check.
Plan view, runway threshold at right. Schematic only: lateral scale and light spacing are exaggerated for clarity.
Configuration
Engineering notes
What an ALS Provides and Where It Is Used
Principal functions
- Runway alignment information
- Roll reference
- Visual indication of the approach direction
- Limited distance-to-go information
- Visual transition from instrument references
- Added guidance in reduced-visibility approaches
Typical applications
- Non-instrument and non-precision runways
- Precision approach Category I, II and III
- Runways supporting low-visibility operations
- Runways needing improved visual alignment
- Airports where terrain or obstacles make approach guidance important
Choose the system for the operational objective, not the runway length. Current Indian AIP data show SALS at 420 m, shorter SALS, CAT I at 720 m or 900 m and CAT II/III precision approach lighting. Use the approved aerodrome design and AIP data, not an assumed standard length.
CAT I, CAT II and CAT III Approach Lighting
| System | Geometry (ICAO/EASA-style) | Key points |
|---|---|---|
| Simple (SALS) | Centreline to 420 m where possible, crossbar at 300 m (18 m or 30 m) | Non-instrument and non-precision runways. |
| Precision CAT I | Centreline, standard length 900 m wherever possible, crossbar at 300 m | Alignment, roll reference, limited distance-to-go, visual acquisition. May be shorter at some airports. Details vary by standard, including centreline arrangements, barrettes and sequenced flashing lights. |
| Precision CAT II/III | Centreline 900 m where possible, two side rows (270 m, or 240 m with demonstrated serviceability), crossbars at 150 m and 300 m. EASA specifies 30 m centreline spacing. | Priority on inner approach availability, accurate geometry, high intensity, reliable supply, secondary power, low-visibility maintenance and monitoring. |
CAT II vs CAT III
ICAO expresses the physical lighting category as precision approach Category II and III, not a separate CAT III visual-aid configuration. Some national systems and manufacturers use separate labels such as CAT II, CAT III or CAT IIIB, so assess the installation against the applicable State regulations, approved runway operation and certification basis.
CAT III is not a lighting-only capability
It depends on ILS performance, AGL, RVR systems, secondary power, taxiway and runway lighting, monitoring, low-visibility procedures, aircraft and operator capability and aerodrome certification. AAI eAIP entries for CAT II/III link the approach lighting to ILS, AGL, RVR and standby power.
For CAT II/III, watch the inner portion. Indian low-visibility procedures can set specific restrictions when a percentage of the approach lights in the inner 450 m is unserviceable. The thresholds are airport- and procedure-specific.
Approach Lighting Configuration and Functional Zones
An ALS configuration is described by the geometric arrangement of centreline lights, crossbars, side rows, barrettes, threshold lights, sequenced flashing lights and supporting structures. It helps to divide the approach area into functional zones. The pattern must stay visually coherent when viewed from the intended approach path.
Threshold zone
The transition between the approach lighting and the runway visual aids.
Inner approach zone
Close-in centreline and lateral visual reference. Especially important for low-visibility operations.
Middle approach zone
Crossbars and centreline lighting give pattern recognition and roll and alignment information.
Outer approach zone
Helps the pilot acquire the runway environment and establish the approach alignment earlier.
FAA Configurations and Terminology
FAA names include ALSF-1, ALSF-2, MALS, MALSF, MALSR, SSALS, SSALF, SSALR and ODALS. FAA describes ALSF-2 as a high-intensity system used for Category II/III approaches, and systems such as MALSR as medium-intensity. FAA describes ALSF-1 as a Category I configuration. MALSR combines steady-burning light bars with sequenced flashers.
Light Units, Barrettes and Flashers
Approach light units
Single sources, multi-lamp barrettes, elevated units, threshold units, crossbar units, sequenced flashers and specialized fixtures. Each must give the required colour, intensity, angular distribution, optical alignment, environmental protection and physical integrity.
Barrettes
A linear group of sources that reads as one visual element, used in centrelines, crossbars, side rows and CAT II/III systems. A strong linear reference beats an isolated point. A partial failure can change the look even while the bar is still lit.
Sequenced flashers
Create a moving effect toward the runway. FAA describes it as a ball of light moving toward the threshold. Verify sequence, direction, timing, synchronization, intensity, aim, circuit independence where specified and control operation.
FAA and EASA material commonly describes the sequence running from the outermost light toward the threshold at about two flashes per second for the applicable configurations. Accept against the governing system specification, not one timing value for every ALS.
Flasher electrical system. Depending on the design: CCR output, isolating transformers, flasher control equipment, high-voltage series connections, trigger or control wiring, individual flasher switching, synchronization circuits and monitoring. Diagnose a flasher fault at both the light-unit and the control/electrical level.
Towers, Masts, Frangible Structures and Foundations
Towers
Needed where the ground profile requires elevated lights to keep the approach-light plane. They carry centreline, crossbar and side-row lights, flashers and barrette assemblies. Design for structural load, wind, foundation, corrosion, cable routing, maintenance access, frangibility or low-impact requirements, the approach-light plane, obstacle clearance and aircraft safety.
Masts
A mast is not only a structural support. Its height sets the vertical geometry. Design it from the light’s station + elevation + vertical aiming angle + photometric coverage. A structurally adequate mast in the wrong position or at the wrong elevation breaks the approved pattern.
Frangible and low-impact structures
Supports sit where an aircraft could contact them, so they must not become an unacceptable hazard. ICAO’s Aerodrome Design Manual Part 6 covers frangibility and says required navigation and safety equipment in specified areas must be frangible and mounted as low as possible. FAA uses Low-Impact Resistant (LIR) structures, with an active AC 150/5345-45C for approach lighting supports.
Foundations
Check coordinates, elevation, orientation, anchors, structural load, concrete, drainage, water ingress, corrosion, cable entry and maintainability. Settlement or movement can cause an aiming error even when the fixture is unchanged.
Related Guides
Junction box and transformer housingApproach Lighting Wiring and Transformers
Electrical chain
An ALS normally forms part of the series-circuit system: CCR → AGL cable → isolating transformer → secondary connector → light unit. Specialized flashers use: CCR/control system → circuit → flasher control/switching → isolating transformer → flasher unit. FAA AC 150/5340-30J gives installation guidance for visual aids and is on FAA’s current list.
Cable design
Consider circuit configuration, voltage rating, insulation, current, length, voltage drop, connector compatibility, transformer rating, circuit impedance, fault behaviour, electromagnetic environment, mechanical protection and maintainability. Coordinate underground cable with ducts, pits, junction boxes, transformer housings, light bases, drainage and access. Protect cable and allow for movement at mast and tower interfaces.
Isolating transformers
Inspect primary and secondary connectors, housing, insulation, moisture, corrosion, leads, physical damage and connection integrity.
Aiming, Elevation, Azimuth and the Approach-Light Plane
Each light must be aligned so that its photometric distribution gives the required pattern from the intended approach path. A fixture can be electrically healthy and still be functionally defective because it is mis-aimed.
Aiming
Vertical angle, horizontal direction, fixture orientation, centreline alignment, crossbar orientation, elevation relationship and beam coverage.
Elevation
Elevation sets the light’s relation to the approach-light plane. A design survey fixes threshold elevation, light station, unit elevation, structure height, terrain profile, the plane and vertical aiming. EASA guidance notes lights may need poles of appropriate height to compensate for ground undulations beyond the stopway or clearway.
Azimuth
The horizontal direction of aim. Centreline lights follow the extended runway centreline, crossbars are perpendicular to it, side rows keep the approved lateral geometry and each unit covers the intended approach sector. Errors cause apparent lateral displacement, uneven pattern, weak centreline guidance and coverage failure.
Horizontal and vertical alignment
Horizontal: centreline station, lateral offset, crossbar perpendicularity, side-row gauge, fixture and structure orientation. Vertical: light elevation, mast height, fixture tilt, beam aim, relation to the plane and terrain. A settled, tilted or struck light needs re-survey and re-aiming. Total stations and GNSS survey can be used, and survey and photometry should complement each other at acceptance.
Approach-light plane. The design should keep installed lights on the approved profile without misleading perspective. EASA guidance stresses avoiding objects that protrude through the plane. Watch uneven terrain, roads, drainage channels, embankments, bridges, railways, buildings, temporary construction, cable structures and elevated service equipment.
Approach Lighting Installation Sequence
Review approved design
ALS type, runway category, configuration, station coordinates, elevations, light and structure types, circuit architecture, control philosophy, photometric requirements.
Establish survey control
Runway centreline, threshold, approach stations, crossbars, side rows, tower and mast coordinates.
Verify site conditions
Terrain, drainage, access, obstacles, utilities, roads, underground services, land ownership, clearances.
Install foundations
Verify coordinates and elevations before installing structures.
Install structures
Masts, towers, light bars, crossbar structures, low-impact or frangible assemblies.
Install cable network
Ducting, cables, connectors, transformers, junction boxes, cable identification.
Install light units
Centreline lights, barrettes, crossbars, side rows, flashers, threshold-associated lights.
Preliminary alignment
Survey equipment and the manufacturer’s aiming method.
Energize and test circuits
Continuity, insulation, transformer connections, CCR, current, switching, control.
Optical alignment
Azimuth, elevation, beam orientation, flasher aim.
Photometric verification
Measure against the approved acceptance criteria.
Finalize documentation
As-builts, survey records, electrical and photometric reports, equipment list, calibration certificates, defect list, acceptance record.
Acceptance Testing
Do not accept an ALS because “all lights are ON”. Acceptance should demonstrate physical, electrical, optical and structural compliance and the documentation.
Physical and structural
- Correct location, stationing, elevation, structure, configuration and fixture type
- Mast and tower condition, foundation, fasteners
- Frangibility or low-impact arrangement
- Cable support, corrosion protection
Electrical
Test with calibrated instruments. Take methods and acceptance values from the electrical design, authority specification and manufacturer. Do not present one universal resistance value for every ALS.
- Cable continuity and insulation
- Transformer connection and circuit current
- CCR operation, brightness stages, control operation
- Earth checks, flasher circuit checks
Optical
A fitting that passes an electrical test can still fail photometric acceptance.
- Intensity, colour, beam spread
- Aiming and coverage
- Flashing sequence where applicable
Documentation
- As-built information, equipment identification
- Calibration certificates, test results
- Non-conformance report and corrective-action record
Barrette test
Verify complete operation, uniform output, correct colour and intensity, orientation, no failed elements and correct beam coverage.
Flasher acceptance test
Every flasher operates, with correct sequence, direction, timing and synchronization, appropriate intensity, no unintended simultaneous flashing and correct control status. Take the flash rate from the governing specification.
Colour verification
Check colour with intensity, since filters, LEDs and optics affect both. Installations may include white approach lights, green threshold lighting and red components in precision configurations.
Aiming test
Design coordinate → installed coordinate → physical orientation → photometric result. Survey the fixture, verify elevation, establish the centreline, set horizontal and vertical aim, energize, measure, fine-adjust, repeat and record the final setting.
Testing workflow
Related Guides
AGL photometric testing guide Runway lighting photometry Testing and commissioning guideMaintenance and Low-Visibility Operations
Daily / weekly
- Light availability and obvious failures
- Flashing operation
- Physical damage and abnormal pattern
- Light units, lenses, structures, flashers
- Visible cable sections, corrosion, foundation condition
Monthly, periodic and annual
- Transformers, connectors, circuit condition, CCR
- Structures, mounting, cable entry, control equipment
- Full physical and structural inspection
- Electrical testing, survey and alignment
- Photometry and flasher testing
- Cable investigation and grounding
- Control-system verification
For CAT II/III, link maintenance to the airport’s Low Visibility Procedures. A current Indian example sets separate serviceability thresholds for the inner 450 m and the portion beyond it. A failed outer light and a failed inner light can have different operational consequences, so do not treat all approach lights as equally significant. Unserviceability of specified portions can suspend CAT II/III operations.
| Defect class | Typical concern | Response |
|---|---|---|
| Critical | Significant loss of required approach guidance or critical low-visibility capability | Immediate operational assessment, urgent rectification |
| Major | Significant degradation of pattern, electrical system or alignment | Priority repair |
| Minor | Local defect with limited immediate effect | Planned repair |
| Observation | Deterioration needing monitoring | Record and trend |
Related Guides
Airport lighting maintenance schedule AGL preventive maintenance guide Emergency power and lighting systemsCommon Approach Lighting Failures
Click a failure to see typical causes.
Failed approach light
Check the chain from source to fixture:
- Lamp or LED failure
- Driver failure
- Transformer failure
- Connector or cable fault
- CCR problem
Incorrect light alignment
Check what moved:
- Foundation settlement
- Mast movement
- Vehicle impact
- Structural deformation
- Incorrect original installation
Uneven light output
Compare against the photometric baseline:
- LED degradation or lamp ageing
- Optical contamination
- Incorrect current
- Damaged optics
- Wrong intensity setting
Flasher not sequencing
Check control and the unit:
- Controller failure
- Trigger wiring
- Power supply
- Individual flasher failure
- Synchronization fault
Water ingress
Find the cause, not only the water:
- Failed seals
- Damaged housing
- Wrong cable entry
- Inadequate drainage
- Damaged connector
Inspect in detail after new installation, runway reconstruction, threshold relocation or displacement, approach-light extension, pavement rehabilitation near foundations, mast or cable replacement, major structural work, ILS approach geometry changes, PAPI relocation and significant terrain or obstruction changes.
ALS, PAPI and ILS
ALS and PAPI
ALS gives runway alignment, roll reference, visual runway acquisition, the approach pattern and limited distance-to-go. PAPI gives vertical approach-path guidance. They are complementary, not substitutes.
ALS and ILS
ILS is a radio-navigation system and ALS is a visual aid. They are designed to work together, because the aircraft transitions from instrument guidance to visual references in the final stages. The ALS must be geometrically compatible with the runway centreline, threshold and approved approach path. It is not an ordinary electrical lighting project.
Approach Lighting in India
Check detailed ALS design and status against DGCA requirements, AAI requirements where applicable, the current AAI eAIP, approved airport drawings, project specifications, runway category, Low Visibility Procedures and manufacturer instructions. Current AAI eAIP publications show CAT I systems of 900 m and 720 m, SALS of 420 m, shorter or abridged SALS, and CAT II/III precision approach lighting. For CAT II/III airports, approach-light availability is tied to LVP serviceability and operational restrictions.
Design Considerations
| Item | Engineering question |
|---|---|
| Runway category | Which operating category does the visual system support? |
| ALS type and length | SALS, CAT I, CAT II/III or national/FAA configuration, and what approved length? |
| Centreline, crossbars, barrettes | Where is the true extended centreline, and how are crossbars and barrettes arranged? |
| Flashers and intensity | Are sequenced flashers required, and what intensity and control stages apply? |
| Elevation and azimuth | What light elevation and horizontal aiming apply? |
| Structures and frangibility | Which tower or mast system, and what aircraft-impact requirement? |
| Wiring and CCR | What circuit, transformer architecture, current and brightness control? |
| Control | Local, remote or ALCMS/ILCMS? |
| Photometry | What field measurements and tolerances apply? |
| Maintenance and documentation | What serviceability programme, drawings, certificates and reports? |
Design photometry in from the start. Fix required intensity, intensity control, beam distribution, colour, orientation, source arrangement, measurement points and tolerances. ICAO’s Aerodrome Design Manual Part 4 covers approach lighting systems and the light characteristics of precision approach runways. The ICAO publication is the 5th Edition (2021) with Amendment 2 dated 15 September 2025.
Electrical architecture
Main and standby supply → AGL substation → CCR → series circuit → transformers → ALS fixtures, with ALCMS/ILCMS control and status feedback. For CAT II/III, secondary power is particularly important. Indian AIP material identifies standby power for AGL as part of CAT II/III capability.
Survey and design tools
CAD, GIS, survey software, photometric modelling, coordinate transformation, lighting calculation, terrain modelling, obstacle assessment, cable calculation, circuit simulation and as-built databases. Major CAT II/III projects integrate civil, electrical, structural, photometric and aeronautical requirements.
Related Guides
Lightning and surge protection for AGL circuits LED airfield ground lighting AGL photometryApproach Lighting Test Report
A test report should let the airport operator, consultant or authority decide whether the installed ALS meets the approved design and applicable acceptance requirements.
Project information
Airport, runway and designation, ALS type, project, contractor, consultant, client, test date.
Applicable documents
Approved drawings and specification, applicable ICAO provisions, DGCA and AAI requirements, manufacturer instructions, inspection and test plan, and the FAA specification only where the project uses FAA standards.
Equipment details
ALS type, light manufacturer, model and source, flasher manufacturer, CCR, transformer, cable and control system.
Survey measurements
Design and actual coordinate and elevation for centreline lights, crossbar, side rows and flashers, with a result.
Electrical test results
Continuity, insulation resistance, circuit measurements, CCR current, brightness stage, transformer condition, control response.
Photometric results
Intensity, colour, horizontal and vertical alignment, beam spread, coverage and acceptance result.
Flasher test
Individual operation, sequence, timing, direction, synchronization, intensity.
Structural inspection
Mast, tower, foundation, fasteners, frangibility or low-impact compliance, corrosion, cable support.
Defects
Defect ID, location, defect, classification, corrective action, retest and status.
Final conclusion
PASS, PASS WITH OBSERVATIONS, or FAIL.
| Equipment item | Details |
|---|---|
| ALS type | |
| Light manufacturer and model | |
| Light source | |
| Flasher manufacturer | |
| CCR | |
| Transformer type | |
| Cable type | |
| Control system |
Survey measurements
| Location | Design coordinate | Actual coordinate | Design elevation | Actual elevation | Result |
|---|---|---|---|---|---|
| Centreline light | |||||
| Crossbar | |||||
| Side row | |||||
| Flasher |
Defect register
| Defect ID | Location | Defect | Classification | Corrective action | Retest | Status |
|---|---|---|---|---|---|---|
| ALS-01 | ||||||
| ALS-02 |
PASS
The system meets the applicable acceptance requirements.
PASS WITH OBSERVATIONS
The system is operational but observations remain.
FAIL
One or more acceptance requirements have not been achieved.
Hold Points and Maintenance Records
Hold point 1: Survey
Coordinates, elevations, centreline, crossbar positions.
Hold point 2: Civil foundations
Dimensions, anchor position, elevation, drainage.
Hold point 3: Structures
Mast or tower type, height, frangibility, installation.
Hold point 4: Electrical
Cables, transformers, connectors, CCR, control wiring.
Hold point 5: Optical
Light-unit and flasher alignment, photometry.
Hold point 6: Final acceptance
Documentation, defects closed, retesting complete, as-builts.
Keep an asset record for each light position: ID, station, coordinates, elevation, type, manufacturer, model, transformer ID, cable circuit, support structure, installation date, maintenance history and photometric history. This shows patterns, for example: ALS-CL-17 repeated low intensity → repeated water ingress → connector deterioration → corrective replacement → photometry restored. That is more useful than “light replaced”.
Common ALS Design and Installation Errors
Treating the ALS as ordinary lighting
It is an aeronautical visual-aid system.
Incorrect centreline coordinates
A small survey error propagates over a long installation.
Incorrect elevation
Wrong mast elevation affects the approach-light plane and optical geometry.
Poor azimuth alignment
The fixture works but gives wrong lateral guidance.
Inadequate structural design
A mast can meet lighting needs yet fail the frangibility requirement.
Incorrect cable architecture
Improper series-circuit connections cause repeated failures.
No photometric acceptance
Electrical operation does not show optical compliance.
No as-built survey
Without final coordinates and elevations, maintenance gets harder.
Mixing ICAO and FAA terminology
ALSF-2, MALSR and ODALS are FAA names. ICAO has its own classification.
Using generic CAT II/III criteria
Acceptance and serviceability come from the applicable authority and approved conditions.
Contractor and consultant scope
Contractor
- Engineering: design review, survey, calculations, drawings, method statements
- Supply: fittings, barrettes, flashers, masts, towers, cables, transformers, connectors, CCR and control
- Installation, termination and control integration
- Testing: electrical, optical aiming, survey, photometry, flasher, CCR and control
- Documentation: as-builts, reports, manuals, spares, acceptance
Consultant
Particularly valuable where the ALS interfaces with ILS, PAPI, runway lighting, secondary power, CCRs, ALCMS and low-visibility procedures.
- Runway classification review, ALS selection, preliminary and detailed design
- Photometric design, electrical architecture, structural and frangibility review
- Specification, BOQ, tender and bid evaluation
- Installation inspection, FAT/SAT coordination, photometric acceptance
- Commissioning and as-built verification
Approach Lighting Acceptance Checklist
Click an item to mark it complete.
Design and survey
Civil, structural and electrical
Optical and documentation
Principal References and ALS Services
Principal references
- ICAO Annex 14 Volume I, 9th Edition (July 2022), incorporating Amendment 18
- ICAO Aerodrome Design Manual Part 4, Visual Aids (5th Edition, 2021, Amendment 2 dated 15 September 2025)
- ICAO Aerodrome Design Manual Part 6, Frangibility
- State, DGCA and AAI requirements, and airport-specific AIP/eAIP data
- FAA documents, including AC 150/5340-30J and AC 150/5345-45C, where an FAA-standard installation is being designed or evaluated
ALS services by Precision AGL Solutions
Specialist engineering support covering ALS design review, survey, installation, electrical testing, photometric verification, aiming and alignment, commissioning and maintenance. The scope depends on the airport’s approved procedures, the applicable authority requirements and the documented project capability.
Discuss an ALS project AGL contractor India AGL consultant India
Quick Knowledge Check
Q1. What are the standard features of the ICAO precision approach Category II/III lighting system?
Q2. Is a CAT I ALS always 900 m long?
Q3. What is the difference between ALS and PAPI?
Q4. Why is electrical operation not enough for acceptance?
Q5. Are ALSF-2 and MALSR ICAO classifications?
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From survey and structures to aiming, photometry and acceptance reports, explore the complete AGL knowledge base.
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Approach Lighting FAQ
Q1What is an airport approach lighting system?
A visual lighting installation extending from a runway threshold into the approach area. It helps pilots establish runway alignment and visual reference during the transition from instrument flight to visual landing guidance.
Q2What is ALS in aviation?
ALS means Approach Light System or Approach Lighting System, one of the major visual aids for runway approach guidance.
Q3What is the difference between ALS and PAPI?
ALS mainly gives runway alignment, roll reference and visual acquisition of the runway environment. PAPI gives vertical approach-slope guidance. They do different jobs and are often installed together.
Q4What is a CAT I approach lighting system?
A precision approach lighting system for Category I approaches. The ICAO/EASA configuration uses a runway-centreline arrangement with a 300 m crossbar and a full design length of 900 m wherever possible.
Q5What is a CAT II/III approach lighting system?
The precision approach lighting configuration for Category II and III operations, with a centreline, side rows and crossbars, and particular importance on the inner approach area and system serviceability.
Q6Is CAT III approach lighting different from CAT II?
Under ICAO classification they are grouped as one precision approach Category II and III lighting system. CAT III operation needs a wider set of aerodrome systems and capabilities beyond ALS.
Q7How long is an approach lighting system?
A simple system is commonly 420 m where practicable, and precision CAT I and CAT II/III systems are based on 900 m wherever possible. Installed systems may be shorter, so check the approved airport configuration.
Q8What are ALSF-1 and ALSF-2?
FAA approach-lighting designations. FAA describes ALSF-1 as a Category I configuration and ALSF-2 as a Category II configuration that may also support Category III operations.
Q9What is MALSR?
The FAA Medium Intensity Approach Lighting System with Runway Alignment Indicator Lights. It combines steady-burning light bars with sequenced flashers.
Q10What are approach lighting flashers?
Sequenced flashing light units that create a moving visual effect toward the runway and strengthen long-range runway identification and alignment.
Q11Why are approach lighting masts frangible?
They stand where aircraft could potentially make contact, so applicable requirements address frangibility or low-impact construction so the support is not an unacceptable hazard. ICAO provides guidance through Aerodrome Design Manual Part 6.
Q12Why is approach lighting photometry required?
Electrical operation does not prove optical compliance. A light can be ON with the wrong intensity, colour, beam spread or aiming.
Q13What tests are required for an ALS?
Typical commissioning tests include survey verification, physical inspection, electrical tests, CCR tests, transformer and connector checks, optical aiming, colour and intensity verification, photometry, flasher sequencing, control-system testing and documentation review.
Q14What should an approach lighting test report contain?
The airport and runway, ALS configuration, equipment, approved criteria, survey results, electrical tests, photometric measurements, flasher results, structural inspection, defects, corrective actions and final acceptance status.
Engineering & Expert Notes
Match the Configuration to the Approach Category
SelectionCheck that the chosen configuration meets the runway's operational requirement and applicable standard.
Survey Positions Carefully
Setting OutSmall positional errors accumulate along a long approach. Use controlled survey data and verify as-built positions.
Aim and Level Every Unit
AlignmentCheck elevation and azimuth during commissioning and after impacts or maintenance.
Structures Must Be Frangible and Stable
StructuresInspect masts, supports and frangible couplings for corrosion, damage and correct installation.
Check Flashing Sequences Under Real Conditions
SequenceConfirm timing and synchronisation, and that equipment recovers correctly after power interruptions.
Record Photometry and Alignment
RecordsCapture measured data at acceptance so later changes can be compared.
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Important Notice, Disclaimer & Limitation of Liability
Please read before relying on any content on this page or on any record downloaded from it.
- Purpose and intended users. This page is an independent educational and informational reference for competent, suitably trained and authorised airfield ground lighting (AGL) and aerodrome personnel. It is not professional engineering, legal or regulatory advice, and using it creates no professional or client relationship. Learning-path and Academy references describe stages of learning only and are not a certification, accreditation or authorisation.
- Safety. Work on series circuits, constant current regulators (CCRs), isolating transformers, cables, connectors and lighting fixtures can be fatal. Always apply the aerodrome’s permit-to-work and isolation/LOTO procedures, prove dead, use correctly rated instruments and PPE, and follow the manufacturer’s instructions. Nothing here authorises work on live equipment or the bypassing of any safety device or interlock.
- Aviation operations. Nothing on this page authorises return to service, the installation, adjustment or modification of any aviation visual aid, a change of operating category (CAT I/II/III), a NOTAM or any aerodrome certification decision. These rest with the aerodrome operator, the air navigation service provider and the competent regulator.
- Standards, regulations and named sources. References to ICAO, FAA, EASA, DGCA, AAI, IEC, IEEE, ISO, BIS and other standards, regulations, AIP material and published sources, and statements about what a named airport, State or authority has published, are summaries for orientation as understood when the page was prepared. They are not official text, may be incomplete, amended or superseded, and have not been independently verified. Consult the current official editions, including the current AIP, AIRAC cycle and NOTAMs. Following this content does not guarantee compliance with any law, standard or approval, and official documents, regulations, the approved design and manufacturers’ instructions always prevail.
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