Standard Operating Procedures for AGL Photometry Testing

The objective of photometry testing is to ensure ICAO-compliant performance of AGL systems by verifying:

• Light intensity — maximum, minimum, and average
• Beam alignment — elevation and azimuth
• Chromaticity — as per CIE 1931 / ICAO Annex 14
• Uniformity across the runway and taxiway

Testing is typically conducted at night, which avoids ambient-light interference with the sensors and minimises disruption to operations.

Proper preparation directly impacts the accuracy of the results.

• Check all fittings for damage
• Clean lenses using a soft cloth and mild soap solution (or the manufacturer-approved method); avoid abrasive or solvent cleaners that can damage optics. If an as-found assessment is needed, measure before cleaning and again after
• Ensure there is no dust, moisture, or deposits on optical surfaces
• Test in dry conditions with no rain, fog or standing water, because a water film on lenses or pavement changes the measured output; record the weather and pavement condition in the report

• Analyse earlier photometric reports
• Identify previously failed or borderline fittings

This helps the testing team focus attention on areas where performance issues may already have been identified.

• Obtain ATC and ASO clearance
• Issue NOTAM and obtain runway-closure approval before testing, as required
• Conduct a briefing between the testing engineer and airport shift in-charge

Proper coordination ensures that testing is carried out within the required operational and safety framework.

Safety compliance is mandatory throughout testing. Before starting the activity:

• All circuits should be operated at full brilliance (the rated maximum current, typically 6.6 A) and allowed to stabilise before measurement
• An emergency response team should be available at the CCR room
• The circuits must be capable of being switched OFF, and the runway released to ATC, within the time agreed (for example, 5 minutes)
• The photometric vehicle driver must avoid damage to elevated fittings
• Tools and support equipment should be available in the vehicle

Photometry testing takes place within an active airfield environment, making operational readiness an essential part of the SOP.

Correct equipment setup and calibration are fundamental to reliable photometric measurements.

Verify constant current regulator output with a calibrated ammeter suitable for the CCR waveform, and record the circuit current during testing, because light output varies with current. Confirm that the photometric sensors carry valid calibration certificates.

Check the measuring system's angle reference and the beam angles before measurement, following the equipment manufacturer's procedure.

The Frame Reader is specifically used where mobile systems cannot perform the required measurements, such as elevated fittings.

For runway and taxiway measurements:

• Conduct measurements along the runway/taxiway at a controlled speed of approximately 40 km/h
• Capture maximum, minimum, and average intensity
• Record beam angles, including toe-in and elevation
• Record light position using GPS/D-GPS

This provides the measurement data required for subsequent analysis and compliance evaluation.

Static or Frame Reader testing is used for PAPI units, Runway Guard Lights, and elevated approach fittings. The process generates iso-candela diagrams and intensity distribution data.

Colour performance is measured to verify compliance with the applicable ICAO standards.

Any failed or underperforming fitting should be immediately reported. The airport maintenance team can then carry out the required corrective action, such as:

• Cleaning
• Alignment correction
• Rectification of electrical issues

After rectification, retesting is carried out. This approach reduces rework and improves efficiency during the available testing window.

All measurements should be stored digitally using the available SD card or system database. The recorded data includes:

• Intensity values
• Beam angles
• GPS location
• Fixture identification

Post-processing generates iso-candela plots, performance curves, and compliance summaries.

Accurate data recording is essential because the final compliance assessment depends on the integrity of the measured and processed information.

Acceptance criteria are evaluated as per ICAO Annex 14 / FAA requirements. The principal requirements include:

• Minimum intensity levels must be achieved (under Annex 14 maintenance provisions, a light whose main-beam average intensity falls below 50% of the specified value is treated as unserviceable)
• Beam spread must fall within defined limits
• The percentage of serviceable lights required for the runway category must be met (Annex 14 maintenance objectives set category-dependent percentages, and limits on adjacent unserviceable lights, for precision approach runways; confirm the figures in the current edition and the CAR)
• Colour must fall within specified chromaticity boundaries

These periodic checks help maintain continued performance verification of the AGL system, as commonly applied under DGCA CAR (Section 4, Series B, Part I) and aerodrome licence conditions. Always confirm the interval against the current CAR edition and your aerodrome's approved maintenance programme, as other regulators and runway categories differ.

The final photometry output includes a system-level performance assessment as well as individual fixture information.

Runway/taxiway-level compliance summary.

Detailed report for selected fittings.

• Intensity — Maximum / Average / Minimum
• Beam alignment
• Chromaticity results
• Compliance status

Reports are generated in PDF format with raw and processed data for audit reference.

After completion of testing:

These activities ensure that the test results are properly preserved, communicated, and converted into actionable maintenance or compliance requirements.