How is a runway fixture selected?
Four decisions, taken in order, that narrow the choice to the right type of runway light.
Choosing a runway fixture is a short chain of decisions. Position decides inset or elevated: centreline and touchdown-zone lights sit in the pavement, as do stop bars at runway holding positions (which may add elevated lights at the taxiway edge), while edge, threshold and end lights are normally elevated. Direction decides unidirectional or bidirectional. Intensity follows the operating conditions, and the light source follows the circuit and the maintenance plan.
The flowchart only narrows the choice. The final fixture is confirmed against the required isocandela diagram and colour, the series circuit and transformer, and the mounting or load rating for its position. An LED fixture must also suit the series circuit and regulator: load, power factor and fault monitoring.
Frequently Asked Questions
Q1How is a runway light fixture selected?
By working through a few decisions in order: where the light sits on the runway, how many directions it must be seen from, the intensity needed for the operating conditions, and the light source and circuit it will run on. The result is then checked against the data sheet.
Q2Which runway lights are inset and which are elevated?
Centreline and touchdown-zone lights sit in the pavement, so they use inset fixtures, as do stop bars at runway holding positions. Edge, threshold and end lights are normally elevated, on frangible mounts, though inset fixtures are used where the layout requires them.
Q3What is the difference between a unidirectional and a bidirectional fixture?
A unidirectional fixture shows light to pilots approaching from one direction only. A bidirectional fixture shows light in two opposite directions and is used where the same position serves both runway directions.
Q4Why does the intensity matter?
Instrument and low-visibility operations call for higher-intensity lights than non-instrument operations, and the intensity class (low, medium or high, depending on the standard) sets the photometric performance the fixture must meet.
Q5What should be checked before the choice is final?
That the fixture meets the required isocandela diagram and colour, suits the series circuit current and transformer, and has the correct frangibility or load rating for its position. The manufacturer's data sheet and the applicable standard decide.
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.