Taxiway Runway Turnoff Light

A Taxiway Runway Turnoff Light is a specialised taxiway guidance fixture that marks the point where an aircraft exits the runway onto a taxiway (turnoff) or enters the runway from a taxiway. These lights provide a clear visual cue for pilots during the critical transition between runway and taxiway operations, typically using a distinctive green/yellow combination to indicate the turnoff point and direction. Turnoff lights are essential for ensuring safe and efficient runway occupancy, preventing runway incursions, and guiding pilots accurately through the complex transition between high-speed runway operations and slower taxiway movements.

The turnoff light's purpose is to mark, unambiguously, the exact point where an aircraft's path shifts from the high-speed environment of the runway to the slower, more constrained environment of the taxiway — a transition that happens quickly after landing and where a missed or late turn can extend runway occupancy time and create a conflict with traffic behind the exiting aircraft. Giving that specific point a distinctive light pattern removes any doubt about exactly where the transition occurs.

Because the same location can also serve traffic entering the runway from the taxiway, the light's visual cue works in both directions of use, helping prevent runway incursions in either scenario: an aircraft mistakenly continuing past its intended exit, or one entering the runway without a clear sense of exactly where the taxiway/runway boundary sits.

Taxiway runway turnoff lights are installed at runway exit points and entrance points where taxiways connect to the runway. They are used on:

• Precision approach runways (CAT II and III) where efficient runway exit is critical
• Rapid exit taxiways where high-speed exits are required
• Busy airports with high traffic volumes requiring rapid runway clearance
• Complex taxiway layouts where accurate turnoff guidance is essential
• Low visibility operations where visual cues are critical
• Military airfields requiring precise ground movement guidance

Fixtures are installed at the specific point where the taxiway centreline meets the runway, positioned to mark the transition clearly for aircraft moving in either direction through that point. Mounting is generally inset, matching the surrounding runway and taxiway lighting at this transition, with the fixture's green/yellow pattern set out precisely at the boundary line surveyed between the two pavements rather than offset into either one. Because this location carries both high-speed runway lighting circuits and taxiway lighting circuits in close proximity, cabling is routed and labelled carefully to keep the two circuits correctly assigned, avoiding a wiring error that could leave the turnoff light following the wrong circuit's brightness steps or switching logic. Position is verified against the specific runway exit design — rapid exit taxiways in particular are angled and radiused for their intended exit speed, so the turnoff light's location is set out to match that specific geometry rather than a standard perpendicular intersection.

Taxiway runway turnoff lights operate as part of the integrated runway and taxiway guidance system:

• Installation: Turnoff lights are installed at the point where a taxiway meets the runway, typically in a row across the taxiway entrance or as a series of lights leading from the runway centreline to the taxiway.
• Lighting: The lights typically emit green light to indicate the turnoff point, sometimes with yellow or amber lights to provide additional cautionary cues. The green light aligns with the taxiway centreline guidance, while yellow provides a cautionary indication for the turnoff.
• Guidance: The lights provide a clear visual path from the runway centreline onto the taxiway, guiding pilots to safely exit the runway and enter the taxiway.
• Integration: Turnoff lights are integrated with runway edge lights, taxiway centreline lights, lead-off lights, stop bars, and other AGL systems to provide seamless transition guidance.

Turnoff lights mark the point where control responsibility hands over from the runway lighting circuits to the taxiway lighting circuits, even though the physical row of lights sits at a single, continuous location. The green and any cautionary yellow/amber elements are typically tied to the taxiway centreline and edge CCR loops rather than the runway edge circuit, so their intensity is stepped by the taxiway lighting control logic, and their loop-level fault reporting is separate from a runway edge fault at the same general area of pavement. Because the fixture's job is to be read correctly at high speed and in a single glance while an aircraft is still moving at landing roll-out speeds, the ALCMS generally keeps turnoff lighting intensity synchronised with the runway lighting step in use for that landing, even though the two are electrically independent circuits — a coordination handled at the ALCMS level rather than by any direct electrical link between the runway and taxiway loops.

Green turnoff fixtures and, where fitted, yellow/amber caution fixtures are each built as separate die-cast aluminium units, anodised or powder-coated against fuel and de-icing fluid exposure, with the LED array or filtered halogen lamp sealed behind an optical prism to reach an IP67/IP68 rating. Flush-mounted installations seat each fixture in an L-868 base can rated for a 100,000 kg (220,000 lb) aircraft wheel load, set flush with the pavement across the runway entrance or along the turnoff path; elevated installations instead mount fixtures on a frangible coupling in an L-867 base can. The green and yellow fixtures are wired through separate 45W–65W and 15W–45W isolating transformers respectively, each housed in its own nearby base can, so the two colour circuits can be tested and faulted independently even though they're laid out together to form a single visual turnoff indication. Sealed L-823 splice connectors carry each circuit back to the primary series cable.