The approach lighting system, seen the way the crew sees it
An approach lighting system is judged from the air, on the centre line, descending. So that is where we measure it. One descent flies the length of the array on the nominal glide path and returns pattern, colour, intensity build-up, coverage, dimming and the flashing row, unit by unit.
Built around how the array is actually laid out
An approach lighting system is not a line of identical lamps. The inspection is modelled on the real thing.
Centre line, crossbars and side rows, each in its own right
Your array is held as individual units on the extended centre line, each one carrying its ICAO Annex 14 system type, where it sits in the row, and the colour it is meant to show. Annex 14 gives an approach system two steady colours: variable white down the centre line and through the crossbars, red on the CAT II/III side row barrettes. A unit deliberately out of service is marked as such, so it is skipped rather than scored as a fault. All three Annex 14 systems are supported, simple, CAT I, and the shared CAT II/III layout.
One descent, the whole array, plus the static checks
The descent starts a kilometre back of the threshold, pushed further out when it needs to be so the pass clears the outermost unit of your array by a margin, then flies down the published glide path and finishes in a hover at the minimum eye height over the threshold. It opens with a standing observation off the end of the array, which is where the attenuation and dimming steps are stepped through and where the sequenced flashing row is timed. Because the drone can hold a fixed point, a flashing row can be counted and a dimming step can be watched settle, neither of which a moving aircraft can do.
What the report answers
The approach lighting rows of the visual aids protocol, each with the tolerance it is judged against.
The approach pattern is the correct shape for the system installed, with every crossbar and side row where it belongs.
Each unit shows the colour its position calls for, variable white on the centre line and crossbars, red on the CAT II/III side rows.
Intensity rises through the approach to the point where the threshold bar reads brighter than the approach units ahead of it, with all units set symmetrically.
The pattern stays visible across the sector either side of the runway axis, measured out from the end of the array.
The pattern stays visible on the runway axis through the whole approach elevation band.
Every unit changes intensity together and by the commanded step, and the runway system stays visible alongside it rather than being washed out.
Intensity is sufficient, the units fire in the direction of flight toward the threshold, and the rate is correct.
The visual guidance seen over the threshold matches the published minimum eye height.
No light on the approach can be mistaken for part of the system, and none dazzles the crew.
Built for both sides of the runway
Airports get compliant inspections without closures. Certified drone operators get a new service line through the partner program.