What is fixture alignment inspection?
The check that each light still points where the design says — aim, tilt and height measured against a reference axis, corrected if it has drifted, then verified after final torque.
Fixture alignment inspection checks that each light still points where the design says. The sequence is prepared and permitted, a reference axis is established, aim, tilt and height are measured in place, any fixture out of tolerance is re-aimed and locked while the circuit is isolated, and the result is verified again after final torque and recorded.
A runway light has a narrow beam, so a small rotation can move its brightest part off the pilot’s line even though the lamp works. Tightening fasteners can disturb an adjustment, so the final check always comes after torque. Re-aiming is hands-on work done with the circuit isolated, locked out and proved dead, under the airport’s permit-to-work. This entry follows the inspection order; installation and in-service alignment are covered in their own entries.
- Prepare. Obtain the permit-to-work and the ATC or airside clearance, collect drawings and design bearings, and confirm the level, gauge and torque tools are in calibration.
- Reference. Establish the runway or taxiway axis, or the reference line the design uses, and mark it.
- Check. Measure each fixture’s aim, tilt and height against the design and note any outside tolerance.
- Adjust. With the circuit isolated and proved dead, loosen, re-aim, level and re-torque the fixtures that are out.
- Verify. Re-check alignment after final torque and, if required, confirm the lit pattern from the pilot’s viewpoint.
- Log. Record the before and after values and trend repeated drift for follow-up.
Frequently Asked Questions
Q1What is a fixture alignment inspection?
It is the check that each light still points where the design says: aimed parallel to its reference axis such as the runway centreline, level or tilted to the design angle, and at the correct height. Any fixture found out of position is re-aimed, locked and re-checked.
Q2Why does a small alignment error matter?
A runway light's beam is narrow, so a small rotation or tilt can move the brightest part of the beam off the pilot's line of approach or roll-out. The light still works, but the pilot sees a weaker or uneven pattern, so alignment errors can go unnoticed without a deliberate check.
Q3What reference is alignment measured against?
Against the line the design specifies, usually the runway or taxiway axis, using the fixture's index mark or reference face, with level and tilt measured against the design angle. The design drawings and manufacturer instructions define the reference and the tolerance.
Q4Why re-check after tightening the fasteners?
Tightening can rotate or tilt a fixture slightly, undoing the adjustment just made. The alignment is verified again after final torque, and the mark or lock is set only once the result is within tolerance.
Q5When is isolation needed?
Measuring aim, tilt and height in place does not open the fixture. Loosening and re-aiming it is hands-on work, and it is done with the circuit isolated, locked out and proved dead, under the permit-to-work. Measuring in place follows the site procedure.
Q6What tolerances and intervals apply?
Angular and height tolerances and the inspection interval come from the airport's maintenance programme, the regulator, the applicable standard and the manufacturer's instructions. Always use the values for your site rather than a generic figure.
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