Runway End Light Photometry Testing — Color Consistency Matters| Rahul Sharma

Runway End Light Photometry Testing — Color Consistency Matters Last night during AGL photometry verification at the runway end, we observed a scenario that still exists at some airports: two different shades of runway end lights operating together — one true RED and the other appearing ORANGE-RED.

As per ICAO Annex 14 and FAA AC 150/5345–46, runway end lights must emit aviation RED within a defined chromaticity boundary. The requirement is not just “red looking light” but a specific wavelength range and chromaticity box measured through photometric and colorimetric testing.

Why Orange-Red Happens (1)Aging halogen lamps (2)Incorrect filter glass (3)Mixed LED and halogen fixtures (4)Voltage imbalance from CCR / isolating transformers (5)Low-quality replacement optics (6)Thermal discoloration of lenses

Negative Effects of Mixed Color (1)Pilot visual confusion during approach or aborted landing (2)Reduced conspicuity in fog or rain (3)Misinterpretation of runway threshold distance (4)Non-compliance during regulatory audits (5)Uneven intensity perception at night

Which Color is Correct? The correct output is ICAO Aviation RED — not orange, not pink, and not amber-tinted red. Any deviation outside the chromaticity limits is technically non-compliant.

How Airports Avoid This Issue (1)Periodic photometric + colorimetric testing (2)Replacement of lamps and filters as a set, not individually (3)Avoid mixing LED and halogen fixtures on the same circuit (4)CCR voltage calibration and circuit load balancing (5)Procurement only from certified OEMs with ICAO/FAA approvals (6)Scheduled preventive maintenance rather than reactive replacement

Conclusion In AGL systems, uniformity is safety. Even small color deviations that appear minor on the ground can create significant perception differences from the cockpit at 2–3 NM final approach. Runway end lights are not just a lighting component, they are a critical visual cue. Ensuring correct chromaticity and consistent output across the runway end line is essential for pilot confidence, regulatory compliance, and safe operations. -Rahul Sharma