How often should fixtures be cleaned?
Windows foul at different rates in different places, and a dirty window dims a light that is still working. Pick a strategy to see how the cleaning interval shapes output.
Output falls below the minimum acceptable level well before the next clean. The light still looks lit, so the shortfall goes unnoticed until it is measured or reported. In this diagram: 2 cleans, 3 stretches below the minimum.
Shorten the interval, or trigger cleaning from inspection and output checks so it happens before the minimum is reached.
Contamination does not arrive evenly. Tyre rubber, dust and sand, oil, fuel and de-icing residues, and grit from snow clearing build up at different rates in different places, and a dirty window delivers less light even when the lamp or LED is working.
A good cleaning interval is planned, not guessed. It aims for the point just before output reaches the minimum acceptable level, set zone by zone from what inspection and output checks show. Too long leaves lights dim; too short wastes runway access and risks wear.
Planning improves with data. Record each clean, the condition found and any output measurement, then adjust: shorten the interval after a dim finding, lengthen it when windows are consistently found only lightly dirty.
Triggers cleaning from inspection and output checks, so effort goes where build-up is fastest.
Simple to schedule, but ignores how fast each zone fouls, so it under-cleans some lights and over-cleans others.
Frequently Asked Questions
Q1How often should inset lights be cleaned?
There is no single interval for every airfield. It depends on traffic, location and how fast windows foul, so it is set zone by zone from inspection findings and output checks, then reviewed.
Q2What contaminates AGL windows?
Tyre rubber, dust and sand, oil, fuel and de-icing residues, and grit left by snow clearing. The mix and the rate differ from one part of the airfield to another.
Q3Why not use one interval for the whole airfield?
Touchdown zones and wheel paths foul much faster than quiet areas. A single interval either leaves fast-fouling lights too dim or over-cleans the rest.
Q4How can you tell a light needs cleaning if it looks lit?
Inspect the window against a clean reference and, where the site procedure provides for it, measure output. Glow seen from above is not a reliable guide to the beam along the runway.
Q5Can cleaning too often cause harm?
It costs access time and labour, and rough or aggressive methods used repeatedly can scratch windows and wear seals. The aim is to clean just before output reaches the minimum, not as often as possible.
Q6What records help plan the interval?
The date of each clean, the condition found on arrival, the method used, and any output measurement. Over time these show how fast each zone fouls and where to adjust.
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