Taxiway Curve Light

A Taxiway Curve Light is a specialized taxiway guidance fixture designed to provide enhanced visual cues at taxiway curves and intersections. These lights feature a distinctive configuration (often angled or additional fixtures) that alerts pilots to an upcoming change in direction, ensuring safe navigation through complex taxiway layouts. Curve lights are typically installed on the outside of taxiway curves to define the curved path and help pilots maintain proper alignment during turns.

A taxiway curve light's purpose is to warn a pilot that the straight-line path they've been following is about to change direction, at a point in the taxi route where the standard centreline or edge lighting alone might not clearly convey the geometry of the turn ahead — particularly at night or in poor visibility where perspective cues are harder to judge. Without this added visual signal, a pilot could misjudge the turn radius and drift toward the pavement edge or shoulder while negotiating the curve.

By marking the outside of the curve specifically, these lights give the pilot a reference for how tightly to turn and where the safe path actually lies, which matters most for larger aircraft with limited manoeuvring margin and for airports with tightly packed taxiway layouts where curves are unavoidable.

Taxiway curve lights are installed on taxiway curves and at intersections where enhanced guidance is required. They are used on:

• Taxiway curves where direction changes significantly
• Complex intersections requiring clear directional guidance
• Rapid exit taxiway curves where high-speed turns are made
• Apron entry/exit points where directional changes occur
• Low visibility operations requiring enhanced curve guidance
• Military airfields with complex taxiway layouts

Through curves, fixtures are set out at reduced spacing compared with the straight-taxiway standard, following the curve's actual radius rather than a fixed interval, using either the standard inset base can recessed into paved sections or an elevated frangible-mount fixture where the curve runs along an unpaved shoulder. Setting-out is surveyed directly off the curve's geometric design (radius and length) rather than a simple offset from tangent points, since under- or over-spacing through the curve is what most commonly produces an uneven or misleading guidance line to the pilot. Cabling and isolating-transformer arrangements follow the same convention as the adjacent straight taxiway centreline lighting.

Taxiway curve lights operate using standard AGL principles with specialized positioning:

• Power: Powered from the constant current series circuit via an isolating transformer (typically 15W – 45W).
• Light Source: Utilizes blue LED arrays or blue-filtered halogen lamps, matching the standard taxiway edge colour.
• Configuration: Installed at closer spacing (typically 7.5-15m) along the curve, with additional lights or angled fixtures to emphasize the turn.
• Guidance: The increased density of lights or angled configuration provides a visual indication of the curve's radius and direction.
• Intensity Control: CCR-controlled intensity with 3 to 5 steps, matching standard taxiway lighting.

Taxiway curve lights are not individually addressable — control is exercised at the loop level through the constant current series circuit, exactly as it is for the straight-section taxiway lighting the curve extends. The tighter spacing and any angled orientation that mark the turn are physical decisions fixed at installation; the control system has no way to adjust geometry in real time, only current. An Airfield Lighting Control and Monitoring System (ALCMS), operated by the tower or ground movement control, selects the required brightness step based on prevailing visibility or ATC instruction. This command is passed to the CCR, which regulates the entire loop to the corresponding fixed current (one of 3 to 5 steps). Every fixture on that loop, whether on the straight approach or through the curve itself, draws from the same current via its own isolating transformer and therefore burns at the same intensity simultaneously — there is no way to make the curve lights brighter than the straight-section lights independently of the rest of the circuit. Fault detection is likewise loop-based: the CCR continuously monitors loop voltage against the commanded current, and a voltage rise at constant current signals increased circuit impedance, typically an open-circuit lamp or a failed isolating transformer, which is reported to the ALCMS as a loop fault rather than pinpointed to an exact fixture without further sectionalised testing.

Every fixture is electrically identical — a blue LED on an isolating transformer off the same series circuit as the straight sections. What actually communicates the turn is spacing: dropping from 15–30m to 7.5–15m through the curve, sometimes combined with angled fixtures, so density itself is the signal a pilot reads for the curve's radius and direction.

The fixture body is a die-cast aluminium alloy housing, machined and anodised or powder-coated for corrosion resistance against runway de-icing fluids, fuel spillage, and UV exposure. A toughened, blue-tinted prismatic lens sits atop the optical assembly, gasket-sealed to the housing with an O-ring or silicone seal to achieve an IP67/IP68 rating against water and dust ingress. Elevated units bolt to a frangible coupling engineered to shear cleanly under aircraft impact loads, seating on an L-861 base can set flush with the surrounding grade; inset (flush) units instead seat into an L-852 base can recessed into the pavement, with the top surface load-rated for aircraft wheel loading. Along curves, fixtures are commonly angled or spaced more densely to maintain a continuous visual guide path through the turn radius. Internal wiring terminates at L-823 primary connectors, sealed splice connectors rated for direct burial and continuous immersion, which mate to the secondary leads of the isolating transformer housed in its own base can nearby. Stainless-steel fasteners are used throughout to resist corrosion, and the base can assembly includes a drainage provision to prevent water pooling around the transformer and cable entry points.