AGL PHOTOMETRY INDIA
Airfield Ground Lighting photometric testing and measurement for runway, taxiway and approach lighting and PAPI — in-field testing of colour, coverage, configuration, chromaticity and aiming, with detailed AGL test reports.
A light being ON does not prove it is performing correctly. Photometry verifies the optical performance of airport visual aids in the field.
What Is AGL Photometry?
Airfield Ground Lighting (AGL) photometry is the measurement and evaluation of the optical performance of aerodrome lighting on runways, taxiways and approaches, and of visual approach guidance systems such as PAPI.
A lighting system may be electrically operational and still fail to provide the required optical performance. A lamp can illuminate, an LED fitting can turn on and a CCR can supply the correct current, yet the actual beam intensity, aiming, colour, coverage or configuration may be outside the applicable requirements. That is why AGL photometric testing matters for commissioning, periodic inspection, maintenance, troubleshooting and performance verification.
In India, AAI tender documents show that in-field photometric testing is actively used for AGL facilities. Recent AAI specifications call for testing of runway, approach, threshold, PAPI and other AGL fittings, with measurements covering colour, coverage, configuration and chromaticity.[1] ICAO's aerodrome visual-aids documentation also addresses the characteristics and performance of approach, runway and taxiway lighting.[2]
The purpose is not simply to confirm that a fitting is ON. It is to determine whether the fitting produces the correct optical output in the intended direction, and whether the installed system performs consistently across the airfield.
Circuit healthy
Transformer healthy
Fitting illuminated
Is it producing the required light, in the required direction, with the required optical characteristics?
Airport lighting is a safety-critical visual system; pilots depend on runway, taxiway, approach and PAPI cues, especially at night and in reduced visibility. This is particularly important for LED AGL: long service life does not prevent optical performance being affected by contamination, damaged optics, incorrect aiming, mechanical movement, ageing, lens deterioration, internal component failure or installation errors.
AGL Photometry and the 4Cs: Colour, Coverage, Configuration, Chromaticity
AAI specifications for AGL in-field photometric testing have used the framework of the 4Cs.[1] These are not a simple lamp-function test.
Colour
The visible colour must be correct for the fitting's function. Incorrect colour can come from incorrect optical components, damaged lenses, LED degradation, contamination, incorrect installation, wrong replacement components or electrical/electronic failures.
Coverage
Whether emitted light gives the intended angular and spatial distribution. Poor coverage can result from incorrect aiming, fixture displacement, damaged optics, incorrect mounting, pavement settlement, mechanical movement or internal optical deterioration.
Configuration
Whether the installation is arranged correctly within the overall visual aid system — for example incorrect fixture spacing, a missing fitting, incorrect orientation, wrong fixture type, incorrect light sequence or a displaced or misinstalled unit.
Chromaticity
An objective way of evaluating colour characteristics rather than relying only on visual judgement. The measurement method and limits should come from the governing specification, not an arbitrary generic value.
AGL Photometry Services in India
An India-focused photometry programme may cover the complete aerodrome lighting system, depending on the airport and project specification.
| AGL system | Typical photometric evaluation |
|---|---|
| Runway edge lights | Intensity, aiming, colour, configuration and coverage |
| Runway threshold lights | Intensity, optical direction, colour and alignment |
| Runway end lights | Intensity, colour and aiming |
| Runway centreline lights | Intensity, colour, configuration and circuit performance |
| Touchdown zone lights | Intensity, alignment and optical output |
| Approach lights | Intensity, configuration, colour and aiming |
| Taxiway edge lights | Intensity, colour, alignment and coverage |
| Taxiway centreline lights | Intensity, colour and alignment |
| Stop bars | Intensity, colour and directional performance |
| Runway guard lights | Optical output and operational condition |
| PAPI | Intensity, colour, beam transition and aiming |
| Elevated AGL fittings | Intensity, aiming, colour and physical alignment |
| Inset AGL fittings | Intensity, optical performance and installation condition |
The exact test matrix should always be based on the applicable ICAO provisions, Indian regulatory requirements, airport-specific specifications, equipment documentation and approved project criteria.
AGL Photometry Equipment: Vehicle-Mounted and Hand-Held Testing
AAI specifications have called for both vehicle-mounted mobile testing equipment and hand-held devices for in-field AGL photometry at Indian airports.[3]
AAI specifications for hand-portable equipment also describe measurement of photometric diagrams, mean intensity, aiming angles and other parameters for AGL and PAPI systems.[4]
Photometric Testing Equipment Airport
Photometric testing equipment for an airport is chosen by the testing scope: vehicle-mounted systems for large runway and taxiway surveys, and hand-held equipment for PAPI, individual fittings and spot checks. Either type should provide calibrated photometric sensors, angular and aiming-angle measurement, colour / chromaticity measurement, data acquisition with reporting software, and calibration documentation. Confirm suitability for the systems to be tested, including PAPI, before mobilising.
Vehicle-mounted testing
Testing every fitting with a manually positioned instrument is slow on large airports. A vehicle-mounted system measures systematically while travelling along a runway or taxiway. Useful for runway edge and centreline surveys, approach lighting, threshold and end lights, taxiway surveys, acceptance testing, periodic maintenance testing and trend monitoring. AAI has tendered in-field AGL photometric testing using vehicle-mounted devices.[3]
Hand-held testing
Useful where a vehicle system is impractical or an individual fitting needs detailed investigation: PAPI measurements, defective-fitting verification, isolated runway or taxiway lights, post-maintenance verification, field alignment checks, troubleshooting, spot measurements and laboratory or workshop evaluation. Portable systems complement, rather than necessarily replace, a vehicle-based survey.
Runway, Taxiway, Approach Lighting and PAPI Photometry
Runway lighting
Edge lights: verify output and orientation (low or inconsistent intensity, incorrect aiming, tilted elevated fixtures, damaged inset fittings, dirty optics, wrong colour, dead or weak units). Threshold and end lights: re-check after maintenance, resurfacing, fixture replacement, civil works or rehabilitation. Centreline lights: identify weak fittings, defective LEDs, wrong colour, optical degradation, damaged inset units and circuit inconsistencies. Touchdown zone: reveals deterioration not obvious in a night visual inspection.
Taxiway lighting
Edge and centreline lights, stop bars, runway guard lights, holding-position and special guidance lighting. Attention to colour, beam direction, fixture orientation, damaged or sunken fittings, contamination, intensity variation and incorrect replacement fixtures. A taxiway fitting may be electrically functional but optically misaligned; photometry provides objective evidence.
Approach Lighting Photometric Testing
Arrays of visual aids give alignment and distance cues. Assessment covers intensity, colour, configuration, aiming, spacing-related installation condition, elevated support alignment, inset light performance and defective or missing fittings. AAI specifications explicitly include approach lights among fittings subject to in-field photometric testing.[1]
PAPI
Depends on both intensity and the correct relationship between white and red sectors. Testing covers luminous intensity, colour, beam transition, unit aiming, horizontal alignment, elevation angle, optical consistency between units and system configuration. A unit can illuminate normally while incorrectly aimed, so visual inspection alone is not enough. Use suitable equipment and the applicable aerodrome specification and authority-approved criteria.
AGL Photometric Testing Procedure
A professional field photometry programme follows a controlled sequence.
1. Document review
AGL layout drawings, runway and taxiway configuration, fitting inventory, fixture type, circuit identification, project specifications, previous photometric reports, maintenance records, PAPI documentation and applicable criteria — establishing what is supposed to be measured.
2. Airfield inspection
Look for damaged, missing or displaced fittings, dirty lenses, broken housings, incorrect orientation, damaged cables, standing water, damaged mountings and signs of pavement movement, so installation problems are not mistaken for measurement anomalies.
3. Calibration verification
Current calibration or verification documentation appropriate to the project. A photometric report is only meaningful when the measurement system itself is controlled.
4. Equipment setup
Configure per the manufacturer's procedure and applicable methodology. Vehicle: vehicle → measurement frame → sensor → data acquisition → analysis software. Portable: operator → portable photometer → fixture → measurement → report.
5. Circuit preparation
Energize the circuit at the appropriate operating condition. Where several brightness stages exist, the test plan must say which are required — on CCR-fed series circuits, measured performance can depend on the operating current level.
6. Measurement
Record the applicable parameters: intensity, angular distribution, aiming angle, colour, chromaticity, photometric curve, fixture position, unit identification and pass/fail status.
7. Data analysis
Process raw data against the applicable requirements and classify results as Pass, Marginal / investigation required or Fail, linked to project criteria rather than a generic industry number.
8. Defect identification
Locate the problem, for example: Runway 09 → edge light no. 47 → low intensity; Taxiway A → centreline unit 18 → incorrect aiming; PAPI 27 → unit 3 → abnormal beam transition. More useful than an overall pass percentage.
9. Corrective maintenance
Cleaning, aiming correction, fixture, optical-component or LED-module replacement, cable/connector repair, transformer replacement, mechanical realignment, housing repair, replacement of damaged fittings and correction of installation configuration.
10. Retesting
Retest corrected fittings where required to confirm the action restored the required optical performance.
AGL Photometry Report and Deliverables
A professional report should provide enough information for traceability and engineering decisions.
Project information
- Airport, runway/taxiway, location
- Date and relevant environmental information
- Test personnel and equipment
Equipment information
- Photometer make/model and serial number
- Calibration information
- Software version
- Vehicle or measurement-frame details
AGL asset information
- Fitting identification and type
- Runway/taxiway location, circuit, unit number
- Fixture technology and position
Measurement results
- Measured photometric values
- Colour / chromaticity
- Aiming and coverage / distribution
- Pass/fail classification and defect comments
Corrective action
- Defect identified
- Recommended and performed action
- Retest result
Final summary
- Total fittings tested and passed
- Fittings requiring correction and retested
- Unresolved observations
AAI tender specifications have also called for formal submission of photometric test reports and corrective measures following field testing.[7]
Defect Categories and Common Problems Found
A useful programme does not simply report "low light" — it investigates the cause, together with electrical testing, physical inspection and maintenance records.
| Observation | Possible cause |
|---|---|
| Low intensity | LED degradation, lamp failure, optical deterioration, incorrect current |
| Wrong colour | Optical/component issue, damaged filter, incorrect fitting |
| Incorrect aiming | Mechanical movement, poor installation, maintenance error |
| Narrow coverage | Incorrect orientation or optical problem |
| Uneven intensity | Fixture degradation or circuit variation |
| PAPI imbalance | Incorrect aiming, optical problem or unit condition |
| Inconsistent readings | Measurement setup or equipment issue |
| Missing fitting | Installation / configuration deficiency |
| Inset fitting weak | Lens damage, contamination, internal failure |
| Elevated fitting misaligned | Frangible support or mounting movement |
Dirty optical surfaces
Dust, oil, rubber deposits and contamination reduce performance.
Incorrect aiming
Sufficient intensity directed outside the intended angular region.
Damaged lenses
Cracks, scratches, discolouration or contamination.
Fixture movement
Impact, loose mounting or other airfield works.
Inset fitting problems
Lens damage, water ingress, pavement contamination, deterioration.
Incorrect replacements
A visually similar but optically different assembly.
PAPI misalignment
Very small aiming errors affect the approach-path indication.
Ageing / electronic degradation
An LED system can operate while optical performance falls.
Photometry vs Electrical Testing
The two are different disciplines that should be considered together; a complete AGL maintenance programme uses both.
| Electrical testing | Photometric testing |
|---|---|
| Checks circuit continuity | Checks optical performance |
| Measures insulation condition | Measures light output |
| Checks transformer condition | Checks beam characteristics |
| Evaluates CCR / circuit operation | Evaluates intensity and distribution |
| Identifies electrical faults | Identifies optical / aiming faults |
| Electrical measurement | Optical measurement |
A fitting with low measured intensity could have a healthy transformer, correct circuit continuity and acceptable insulation resistance — and still have a defective optical assembly.
Visual inspection finds lights that are off, obviously damaged, wrong-coloured, missing or visibly misaligned, but cannot reliably quantify optical performance. Photometry gives measurement → evidence → comparison → defect identification → corrective action → retest, which is far more valuable for engineering acceptance and asset management.
Photometry in Commissioning, Existing Airports, Compliance, LED and CAT II/III
Commissioning
Sequence: installation → electrical testing → functional testing → energization → photometric testing → corrections → retest → final acceptance → documentation. At new runways, extensions, taxiway construction, rehabilitation, LED conversion, approach modifications, PAPI relocation, CAT II/III improvements and major upgrades, it identifies installation defects before handover.
Existing airports
Existing systems may mix legacy lamps, LED fittings, mixed fixture types, older transformers, new and old circuits and replacement fixtures from different manufacturers. Photometry establishes actual field condition. AAI has awarded and tendered dedicated photometric work at operational airports, including testing of all AGL at Hyderabad Airport, Begumpet, and other airport-specific photometric surveys.[5]
DGCA compliance
An AAI 2026 tender for Ranchi Airport sought in-field photometric testing of AGL using vehicle-mounted and hand-held equipment as part of compliance with DGCA observations.[3] Photometry is not only a design or commissioning activity — it can be an operational compliance and corrective-maintenance activity. Acceptance criteria must come from the applicable DGCA requirements, ICAO provisions, airport specifications and approved documents.
LED airport lighting
LED removes many lamp-related problems but not optical ageing, lens contamination, damaged optics, thermal degradation, electronic faults, incorrect replacement assemblies, alignment errors or incorrect installation. Periodic photometry works as a performance-monitoring tool: initial test → annual test → trend comparison → reduced performance → corrective maintenance. Historical data becomes part of asset management.
Preventive maintenance
Photometric data supports condition-based maintenance: spot gradual intensity reduction, repeated failures at one location, systematic aiming problems, colour deterioration, recurring circuit abnormalities and fixture types with higher failure rates — directing resources to assets that need attention.
CAT II / III operations
A performance programme for low-visibility operations may include regular visual inspections, functional checks, photometric testing, fixture condition monitoring, PAPI verification, circuit and CCR checks, corrective maintenance and documented retesting. Frequency and acceptance requirements come from the operational approval, regulations, airport procedures and approved maintenance programme.
AGL Photometry for Airport Projects
Photometric testing can support several stages of an airport project.
Design verification
Verify installed equipment performs as intended in the field.
Construction QA/QC
Identify installation-related optical errors.
Pre-commissioning
Before final acceptance and operational handover.
Commissioning
Part of complete AGL system performance evaluation.
Periodic inspection
Monitor ongoing lighting performance.
Maintenance
Identify defective or deteriorated fittings.
Rehabilitation
Before and after major AGL replacement programmes.
Regulatory / inspection response
Objective data for corrective-action programmes.
The Indian AGL Photometry Market and How to Select a Provider
AGL photometry is an established airport engineering service in India. Current AAI procurement records include dedicated AGL photometric field testing at Madurai Airport in 2026, and other AAI documents specify vehicle-mounted and hand-held systems.[6] AAI technical documents also specify field testing of approach, runway edge, runway end, threshold and PAPI fittings, with reporting and corrective measures.[7]
This creates demand for providers who combine photometric equipment + AGL engineering knowledge + field testing + data analysis + corrective guidance + retesting.
Suitable equipment
Measurement equipment appropriate for the AGL systems being tested.
Calibration and traceability
Controlled calibration / verification documentation appropriate to the contract.
Runway and taxiway experience
Methodology changes with fitting type and installation.
PAPI capability
Aiming, beam transition and optical performance expertise.
Vehicle-mounted testing
Can substantially improve efficiency on large airports.
Hand-held testing
For detailed investigation and individual fixture verification.
Reporting quality
Technically useful, traceable to individual fittings and suitable for corrective action.
Understanding of standards
Difference between ICAO provisions, DGCA requirements, AAI specifications, project specifications, manufacturer requirements and FAA criteria where a project calls for them. FAA requirements should not automatically be treated as Indian or ICAO requirements.
Project
- Approved AGL layout
- Fixture inventory and circuit information
- Applicable specifications
- Previous test results
Equipment
- Photometer and calibration/verification records
- Measurement frame and vehicle where applicable
- Portable equipment
- Data-logging system
Airport
- Runway/taxiway availability
- Operational restrictions and airside access
- Lighting circuit identification
- Safety coordination
Measurement
- Correct fixture identification
- Correct operating condition and test geometry
- Sensor positioning
- Stable acquisition; repeat where necessary
Reporting
- Raw / processed results
- Failure list and location reference
- Corrective recommendations
- Retest status and final summary
ICAO and Indian Requirements for AGL Photometry
Photometry should always be performed against the correct governing requirements.
ICAO Annex 14 Volume I is a core international reference for aerodrome design and operations; the ICAO Store lists the 9th Edition (July 2022) with Amendment 18 dated 4 August 2025 and subsequent corrigenda issued in 2026.[8] ICAO's Aerodrome Design Manual Part 4, Visual Aids, addresses visual-aid characteristics including approach, runway and taxiway lighting; the store lists it as the 5th Edition, 2021.[2]
For Indian projects, the applicable DGCA requirements, AAI technical specifications, airport procedures and contract documents must also be considered. AAI field-testing specifications illustrate how ICAO/DGCA requirements are incorporated into actual Indian airport work packages.[1]
Acceptance criteria vary with the project and operational category, so this page deliberately does not publish universal numerical pass/fail values. Always take them from the exact applicable standard or project specification.
AGL Photometry India — Precision AGL Solutions
Photometric testing is most useful when it goes beyond collecting measurements and produces actionable engineering information.
Precision AGL Solutions offers India-focused AGL photometry covering field measurement, runway and taxiway lighting evaluation, PAPI testing, colour and chromaticity assessment, aiming verification, defect identification, reporting and retesting, subject to the applicable airport project requirements.
Final engineering perspective. AGL photometry is the link between an installed airport lighting system and its actual optical performance in the field. The electrical system may be healthy and the light may be ON, yet an optical problem can remain. Modern AGL quality control combines electrical testing + functional testing + physical inspection + photometry + corrective maintenance + retesting — verifying the performance, consistency, maintainability and operational readiness of airport visual aids.[6]
Frequently Asked Questions
What is AGL photometry?
Why is photometric testing required when all the runway lights are working?
What AGL systems can be tested?
Can PAPI be tested using AGL photometry equipment?
What is 4C AGL testing?
Is vehicle-mounted photometry better than hand-held testing?
How often should AGL photometry be performed?
Does photometry replace electrical testing?
Can photometry be used after LED conversion?
What should an AGL photometric report contain?
Explore the India AGL Knowledge Hub
Need AGL Photometry in India?
For airport operators, EPC contractors, consultants and AGL maintenance teams — share your airport, runways and taxiways, PAPI details and the applicable specification, and we will revert with next steps.
Sources & References
- Airports Authority of India — technical specification for in-field AGL photometric testing (4C)
- ICAO Store — Aerodrome Design Manual Part 4, Visual Aids (Doc 9157)
- Airports Authority of India — tender search (in-field AGL photometric testing, vehicle-mounted and hand-held)
- Airports Authority of India — GeM NIT, S.V. Airport, Raipur (hand-portable photometric equipment)
- Airports Authority of India — tender contract awards (AGL photometric testing)
- Airports Authority of India — tender search (AGL photometric field testing, Madurai 2026)
- Airports Authority of India — tender document (field testing and reporting of AGL fittings)
- ICAO Store — Annex 14, Aerodromes
External sources were referenced when this page was prepared; tender listings, specifications and regulatory documents change over time. Always confirm requirements against the controlled documents for your project.
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