How is photometric acceptance decided?
Checking the 4Cs, Colour, Candela, Coverage and Configuration, then accepting or rejecting the fixture.
Photometric acceptance is the decision that closes the photometric work, and it rests on the 4Cs: Colour, Candela, Coverage and Configuration. Together they show whether a fixture gives pilots a precise and compliant visual signal.
Colour is the chromaticity of the light. Candela is its intensity. Coverage is the beam spread and orientation across the required viewing angles. Configuration is the placement, spacing and layout pattern of the fixtures on the runway or taxiway. The fixture is accepted only if all four are met. If colour, candela or coverage fails, the fixture is rejected, the cause is found and corrected, and it is retested; if configuration fails, the layout is corrected and rechecked. Acceptance applies at two levels: the fixture type is accepted on a laboratory photometric report, and installed lights are checked on site for aim and output. The decision is recorded so it can be traced.
Frequently Asked Questions
Q1What is photometric acceptance?
The decision on whether a fixture is passed after photometric testing. It is made on the 4Cs, Colour, Candela, Coverage and Configuration, and the fixture is accepted only if all four are met.
Q2What are the 4Cs of AGL photometry?
Colour (chromaticity), Candela (intensity), Coverage (beam spread and orientation) and Configuration (placement, spacing and layout of the fixtures). Together they show whether the signal is precise and compliant. The 4Cs are a teaching framework used here, not an ICAO-defined term.
Q3How does Configuration differ from the other three Cs?
Colour, Candela and Coverage describe the light from one fixture and are measured on the test bench. Configuration is about how fixtures are laid out on the airfield, so it is checked against the layout requirements.
Q4What happens if one of the 4Cs fails?
If colour, candela or coverage fails, the fixture is rejected, the cause is traced to the colour source, optics, aim or set-up, corrected, and the fixture is retested. If configuration fails, the layout is corrected and rechecked; the fixture itself is not at fault.
Q5Is acceptance the same as data interpretation?
No. Interpretation reads what the data shows. Acceptance is the formal decision, made against the criteria, that the fixture and its arrangement are passed or not.
Q6Why is the decision recorded?
So the approval can be traced. The results, the criteria used and the outcome form part of the test record that goes into commissioning.
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