Elevated Taxiway Light

An Elevated Taxiway Light is a standard taxiway guidance fixture mounted on a frangible pole or base plate above the pavement surface. These lights emit the characteristic blue light that defines taxiway edges, providing pilots with clear visual guidance during ground movement. Elevated taxiway lights are the most common configuration for taxiway edge lighting, particularly on grass or soft shoulders where inset fixtures are not practical. The elevated design offers excellent visibility from a distance and is easy to maintain, making it the preferred choice for most airfield taxiway applications.

The elevated taxiway light exists to give pilots the strongest, most visible lateral reference the AGL system offers, using height and a frangible above-ground mount to project the blue edge signal further and more clearly than a flush fixture can — particularly valuable on grass or soft shoulders where an inset light isn't a practical option at all. Because visibility at a distance matters most where a pilot needs the earliest possible cue to track a taxiway edge, the elevated design is the default choice wherever ground conditions permit it.

The frangible mounting is itself part of the purpose, not just a construction detail: it lets the fixture break away safely if struck by an aircraft or vehicle, protecting both the aircraft and the light from a rigid-obstacle collision, so the airfield gets the visibility benefit of an elevated light without introducing an unacceptable strike hazard.

Elevated taxiway lights are installed on taxiways with grass, gravel, or soft shoulders where inset fixtures are not feasible. They are used on:

• Taxiways with grass or soft shoulders where elevated mounting is required
• All paved taxiways as the standard edge lighting configuration
• Apron edges where elevated lights provide clear boundaries
• Rapid exit taxiways requiring high visibility edge guidance
• Military airfields where robust lighting is required
• General aviation airports with cost-effective lighting needs

Elevated taxiway fixtures mount on a frangible coupling atop an L-867-type base can set flush with grade along the taxiway edge or shoulder, used wherever the adjacent surface is grass, gravel, or otherwise unsuited to an inset fixture. The base can foundation is set back at the taxiway's edge safety margin, with fitting height kept low enough to stay clear of aircraft wingtip and engine clearance envelopes. Cable is run in a trench from the base can back to the isolating transformer pit and on to the taxiway lighting series circuit, with setting-out tied to the taxiway centreline survey so the edge row stays parallel to the paved surface along its full length.

Elevated taxiway lights operate using standard AGL principles:

• Power: Powered from the constant current series circuit via an isolating transformer (typically 15W – 45W) buried near the fixture.
• Light Source: Utilizes blue LED arrays or blue-filtered halogen lamps. The distinctive blue colour is universally recognized as a taxiway edge indicator.
• Beam Pattern: Projects an omni-directional or uni-directional beam pattern to guide pilots along the taxiway.
• Mounting: Mounted on a frangible pole or base plate approximately 300-500mm above ground level, with a breakaway design to minimize aircraft damage on impact.
• Intensity Control: CCR-controlled intensity with 3 to 5 steps, on the standard 6.6A series circuit range (2.8A – 6.6A at full brightness).

Elevated taxiway lights are not individually addressable — control is exercised at the loop level through the constant current series circuit. An Airfield Lighting Control and Monitoring System (ALCMS), operated by the tower or an automated visibility-linked routine, selects the required brightness step based on prevailing RVR, ATC instruction, or (at smaller aerodromes) pilot-controlled lighting input. This command is passed to the CCR, which regulates the entire loop to the corresponding fixed current (typically one of 3 to 5 steps between 2.8A and 6.6A, with 6.6A as the full-brightness step). Every fixture on that loop, via its own isolating transformer, draws from the same current and therefore burns at the same intensity simultaneously — there is no way to dim or brighten a single fixture 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. Because the fixture sits on a frangible coupling, a sheared coupling looks electrically identical to any other open-circuit fault on the loop — the ALCMS reports it the same way, and only a field inspection confirms whether the cause was impact damage or a failed component.

The fixture head is a die-cast aluminium alloy housing, anodised or powder-coated for corrosion resistance, with a low-profile optical assembly under a toughened-glass or high-strength polycarbonate lens, gasket-sealed with an O-ring for an IP67/IP68 rating. The characteristic blue colour is produced by a filtered lens or coloured LED array rather than a dyed housing, keeping output stable as the fixture ages. The head mounts on a frangible coupling atop an L-867-type base can set flush with grade, the coupling engineered to shear cleanly if struck by an aircraft wingtip, vehicle, or ground-support equipment, minimising damage below the break point. Internal wiring terminates at L-823 primary connectors, sealed for direct burial and continuous immersion, mating to the isolating transformer's secondary in an adjacent base can, with stainless-steel fasteners used throughout and a drainage provision in the base can to keep the connector joint clear of standing water.