What is approach-light alignment?
How the approach lights are lined up on the runway centreline, held in a level plane, and aimed along the approach so the pattern reads true to the pilot.
Approach-light alignment has three parts. Lateral position: each centreline light sits on the extended runway centreline, evenly spaced, with crossbars square to it. Level: the lights are placed as nearly as practicable in a horizontal plane through the threshold, so supports grow taller where the ground falls away. Aim: each fixture is turned and tilted to send its beam up the approach path.
Pilots read the lights as one pattern leading to the runway. A light that is off line breaks the pattern, and one aimed wrongly can look dim or uneven from the cockpit while still being on. The line is set out from survey control, the aim is set with an inclinometer to the system’s aiming schedule, and both are checked again after replacement, impact or ground movement, and during inspection.
Frequently Asked Questions
Q1What is approach-light alignment?
Setting each approach light in the right place and aiming it the right way: on the extended runway centreline, in line with its neighbours, in the intended horizontal plane, and aimed along the approach path.
Q2Why does alignment matter?
Pilots read the approach lights as a pattern that leads to the runway. A light that is off line or aimed wrongly breaks that pattern, or looks dim from where the pilot is, and can mislead the lateral guidance.
Q3What are the parts of alignment?
Lateral position on the centreline, spacing along it, the mounting height or plane, and the aim, which is the rotation toward the approach and the vertical tilt.
Q4How is it set out and checked?
The centreline is set out from survey control. Lights are levelled and aimed during installation, and the aim is verified with a surveyor’s instrument and an inclinometer, then checked again by eye from the approach.
Q5When is alignment rechecked?
After a fixture or mast is replaced, after impact or ground movement, and during routine inspection. A misaligned light still shows, so a fault is easy to miss without a check.
See It. Understand It. Then Learn How to Engineer It.
Recognising an AGL system visually is the first step. The next step is knowing how to design, install, test, commission and maintain them correctly.
Build Practical AGL Engineering Skills
Go deeper with structured training from Precision AGL Academy, covering:
Learn how each light, sign and circuit works as part of a complete airport lighting system, not just as an isolated diagram.