Taxiway Turnoff/Runway Exit Indicator Fixture

A Taxiway Turnoff/Runway Exit Indicator Fixture is a combined guidance fixture that integrates both turnoff indication and runway exit marking into a single, cohesive lighting solution. These fixtures use a distinctive pattern of green and yellow lights to clearly define the runway exit point and guide pilots through the transition from runway to taxiway, enhancing safety and efficiency during the critical post-landing phase. The fixture typically incorporates multiple light sources in a single housing, providing both the green taxiway centreline guidance and yellow cautionary indication for the exit point. This integrated design reduces installation complexity, improves reliability, and provides a consistent visual cue for pilots.

This combined fixture exists to handle two related but distinct messages at exactly the moment a pilot needs both simultaneously: the runway exit is here, and proceed with the appropriate caution as you make that transition. Rather than requiring a pilot to process two separate fixtures at slightly different points during the highest-workload phase right after touchdown, integrating both cues into one cohesive signal reduces the chance of missing either message during that critical transition.

Combining turnoff guidance and exit marking into a single housing also reduces the physical and electrical complexity of the installation at what is often a geometrically awkward point on the airfield, while still delivering the same clear green/yellow visual language pilots already recognise from standard taxiway and caution lighting elsewhere on the field.

Taxiway turnoff/runway exit indicator fixtures are installed at runway exit points where taxiways connect to the runway, particularly at busy airports with complex ground movement patterns. They are used on:

• Precision approach runways (CAT II and III) where efficient and safe runway exit is critical
• Rapid exit taxiways where high-speed exits require clear visual cues
• Busy international airports with high traffic volumes and complex taxiway layouts
• Low visibility operations where integrated guidance is essential
• Military airfields requiring robust and reliable ground movement guidance
• Airports with multiple intersecting taxiways where exit point confusion is a risk

The combined fixture is installed at the runway exit point in place of what would otherwise be two separate fixtures, set into the pavement at the surveyed boundary between the runway and the exit taxiway so both the green centreline guidance and the yellow exit caution are presented from the same physical location. Because the unit integrates multiple light sources into a single housing, its base can and cable entry are sized accordingly, with the internal wiring between light sources and terminal block completed at manufacture rather than requiring several individual connections to be made up in the field. The fixture's single housing simplifies the pit and duct layout at this location compared to installing separate turnoff and exit fixtures, though the two lighting functions within it are still typically wired to preserve independent circuit assignment where the site's design calls for it. Positioning is tied to the specific rapid-exit or standard-exit geometry of the runway it serves, matching the fixture to the same surveyed reference used for the runway edge and threshold lighting it sits alongside.

Taxiway turnoff/runway exit indicator fixtures operate as an integrated guidance system:

• Integrated Design: The fixture combines multiple light sources in a single housing, typically including green lights for the taxiway centreline and yellow lights for cautionary indication at the exit point.
• Guidance Pattern: The fixture may use a combination of steady and flashing lights to provide clear directional cues. Green lights indicate the correct path onto the taxiway, while yellow lights provide a cautionary alert for the turnoff.
• Positioning: The fixture is installed at the runway exit point, aligned with the taxiway centreline, providing a clear visual path from the runway onto the taxiway.
• Integration: The fixture is integrated with runway edge lights, taxiway centreline lights, lead-off lights, stop bars, and other AGL systems to provide seamless transition guidance.
• Control: The fixture is controlled by the CCR and ALCMS, with intensity adjustment to match prevailing visibility conditions.

Although the green and yellow elements share one housing, they are not one controlled object — each colour is typically wired into its own series circuit (green onto the taxiway centreline loop, yellow onto a separate cautionary or guard-light circuit) with its own CCR and its own loop-level fault detection. The ALCMS commands the two independently, which is why a fixture can show green without yellow, or vice versa, depending on which circuit is energised at that moment. This also means the fixture reports as two separate points in the control architecture despite being one physical unit: a fault on the yellow element's circuit raises a loop fault on that circuit alone, with the green element and every other fixture on the centreline loop unaffected, and a technician diagnosing a "half-lit" fixture is really diagnosing one of its two independent circuits, not the housing as a whole.

Unlike a turnoff light built from separate green and yellow fixtures, this component integrates both LED arrays or filtered halogen lamp sources into a single die-cast aluminium housing, anodised or powder-coated against fuel and de-icing fluid exposure. Each light source keeps its own optical prism and internal leads within the shared body, gasket- and O-ring-sealed to an IP67/IP68 rating as one unit. The fixture is typically flush-mounted in an L-868 base can rated for a 100,000 kg (220,000 lb) aircraft wheel load, though elevated versions on a frangible coupling in an L-867 base can are also used. Despite sharing a housing, the green and yellow circuits remain electrically separate all the way to two independent sealed L-823 splice connectors, each feeding its own isolating transformer — a design that trades the installation simplicity of one housing for the maintenance complexity of testing two circuits within it, which is the main consideration when choosing this fixture over separate turnoff and caution lights.