What is approach-light installation?
Putting each light of the approach line into service — set out from survey on the extended runway centreline, fixed on a flush foundation through a frangible stem or mast, connected to its transformer and cable, then aimed and proved.
Approach-light installation is putting each light position of the approach line into service: set out from survey on the extended runway centreline, fixed on a foundation whose top is flush with the ground, raised to the design height on a frangible stem or mast, connected to its transformer, cable and earth, then fitted with its fixture, aimed and proved.
The pilot reads the line as one regular pattern, so a position that is out of line, at the wrong height or aimed wrongly shows up as a kink, a gap or a dim light on the approach. Set every position out from survey rather than by eye, make the height with the structure and keep the foundation flush, keep the break point clear of added bracing or tight cable, and read the aim again once the fixings are tight. See Installation Sequence for the order of work along the whole line and Approach-Light Alignment for the aim. Work is often at height, beyond the fence and under low aircraft, so follow Approach-Light Work Safety, and treat the circuit as live until it has been isolated, locked out and proved dead.
- Isolate. Isolate at the CCR, lock out, prove dead, and hold the permit and the ATC or airport-operations clearance.
- Set out. Mark each position from survey control on the extended centreline at the designed spacing, and check the line before digging.
- Mount. Check the foundation is cured and flush, then fix the stem or mast on its frangible coupling, plumb and at the design height.
- Connect. Connect the transformer primary to the series cable and the secondary lead to the fixture, bond to earth, then seal every entry and connector.
- Aim. Fit the fixture, set it to the design aiming angle, and read it again after tightening.
- Test and record. Prove insulation and continuity, check the light works, record the as-built position and clear all tools from the area.
Frequently Asked Questions
Q1What is approach-light installation in AGL construction?
Putting each light position of an approach lighting system into service. For every position it covers setting out from survey, fixing the frangible stem or mast on its foundation to the design height, connecting the transformer, cable and earth, fitting the fixture, aiming it, and proving it before the line is energised.
Q2Why is every light set out from survey rather than by eye?
The lights have to lie on the extended runway centreline, at the designed spacing and in the designed plane, so that the pilot sees one regular pattern. A position out by a small amount shows up as a visible kink or gap in the line. Mark each position from survey control and the drawings, and check the line before any ground is broken.
Q3How is the height of an approach light set?
By the frangible structure, not by the foundation. The foundation top stays flush with the finished ground so that it is not a solid obstacle, and the stem or mast is made up to the design height so that the fixture sits in the designed plane. Keep the structure plumb, and do not add bracing, grout or fixings that bridge the frangible break point.
Q4What is connected at each light position?
The isolating transformer’s primary is connected into the series cable, and its short secondary lead is run through the duct to the fixture. The structure and fixture are bonded to the earthing system as the design requires. Make the connections as the manufacturer specifies, keep the cable slack so it does not hold the structure up, and seal every entry and connector.
Q5What is checked before an approach light is left?
Check that the structure is plumb and the couplings are as specified, the fixture is clean and aimed at the design angle, and the connections are sealed. Prove insulation and continuity on the circuit, check that the light works, clear all tools from the area and record the as-built position. The line is energised only after the circuit tests are complete.
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