What is fixture alignment at installation?
Pointing the light where the design says — the fixture’s index mark brought onto a line parallel to the runway axis, the fixture levelled, then locked and re-checked after the bolts are torqued.
Fixture alignment at installation is setting each fixture so its beam axis points where the design requires, usually parallel to the runway or taxiway axis. A reference line is set out from the design, the fixture’s index mark is brought onto it, the fixture is levelled, and it is locked in place as part of fixture installation.
A small rotation at the fixture becomes a larger miss at the pilot’s distance, so a light that looks tidy up close can send its beam off the intended viewing positions. Narrow-beam lights are the least forgiving. Alignment follows base-can positioning, which fixes where the can sits, and fixture orientation, which decides which way the fixture faces. Check the alignment again after the bolts are torqued, because tightening can turn or tilt the fixture. Work only on a circuit that has been isolated, locked out and proved dead.
- Isolate. Switch off, lock out and prove the circuit dead before any work.
- Mark out. Set a string line, laser or survey offset parallel to the axis through the base can.
- Orient. Bring the fixture’s index mark or alignment arrow onto the line, or use the manufacturer’s alignment tool.
- Level. Check the fixture with a spirit level and correct any tilt before it is fixed.
- Lock. Tighten the bolts or coupling to the specified torque without letting the fixture turn.
- Verify and record. Re-check the mark and level, confirm the light works, clear all tools and log the result.
Frequently Asked Questions
Q1What is fixture alignment during installation?
Setting the fixture so its beam axis points exactly where the design requires, usually parallel to the runway or taxiway axis, and holding it there while it is fixed. It covers marking the reference line, bringing the fixture’s index mark onto it, levelling the fixture, locking it and checking the result.
Q2How is a fixture aligned to the runway axis?
Set a reference line, such as a string line, laser or survey offset, parallel to the axis through the base can. Bring the alignment mark on the fixture onto that line, or use the manufacturer’s alignment tool or jig, then check the fixture is level. Follow the design drawings and the manufacturer’s installation data.
Q3Why does a small alignment error matter?
The beam leaves the fixture at an angle, so a rotation error at the fixture becomes a larger miss at the pilot’s distance. The beam can then fall off the intended viewing positions and the light can look dim or uneven. Narrow-beam lights, such as centreline and touchdown zone lights, are the least forgiving.
Q4How is alignment different from orientation and base-can positioning?
Base-can positioning decides where the can sits. Orientation decides which way the fixture faces, for example which side shows green or red. Alignment is the accuracy of that aim, held within the tolerance in the design and the manufacturer’s data.
Q5Why check alignment again after torquing the bolts?
Tightening can turn or tilt the fixture slightly, so a fixture that was square before torquing may not be square after it. Check the index mark and the level again with the bolts at their final torque, before the area is handed back, and record the result. Work only on an isolated circuit that has been locked out and proved dead.
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