Runway End Light

A Runway End Light is a red light fixture installed at the end of a runway. These lights are arranged in a single row extending across the full runway width, with the number of fixtures set by that width (spacing must not exceed 3 m, per ICAO Annex 14 / FAA AC 150/5345-46), and are uni-directional, projecting light only in the approach direction. The red colour signifies the end of the runway available for landing, distinguishing it from the green threshold lights at the opposite end. Runway end lights are a critical safety feature, alerting pilots that the runway surface is about to end and that they must either stop or go around.

The runway end light exists to give a pilot an unmistakable, unambiguous cue that usable runway is running out, so the decision to land, stop, or go around can be made with confidence rather than guesswork. Because the fixture is uni-directional and only visible to traffic approaching from the runway side, it cannot be mistaken for a threshold or edge light from the landing direction, and its red colour is reserved exclusively for this "end of pavement" warning across the entire airfield lighting system. This makes it a terminal safety reference during rollout after landing and a hard boundary marker during takeoff, particularly in low-visibility or night operations where the physical edge of the pavement is otherwise difficult to judge.

Installed at the end of all paved runways that support night operations. The lights extend as a single row across the full runway width, on a line at right angles to the centreline, with spacing between adjacent lights not exceeding 3 metres; the outermost lights sit on, or up to about 3 metres outside, the runway edge to match the runway edge light line. Runway end lights are used on both precision and non-precision runways, and are also installed at the end of displaced thresholds where applicable. They work in conjunction with threshold lights to clearly define the runway limits.

Fixtures are set out in a single row on (or just beyond) the physical end of the runway, square to the centreline, at the spacing dictated by runway width so no gap between adjacent lights exceeds the design maximum. Units are almost always inset (flush) fittings seated into an L-868 base can recessed into the pavement or paved shoulder, sealed against surface water and jet-blast debris, since the runway end typically falls within a frangibility-sensitive zone where elevated fixtures are avoided. Each base can is fed by armoured cable run in duct back to its isolating transformer, with the transformer housed in its own secondary base can to keep the series-circuit joint clear of standing water. The optical assembly is oriented uni-directionally toward the approach, so alignment is checked against the runway centreline survey during setting-out to confirm the beam is aimed correctly at arriving traffic. Where the runway end coincides with a displaced threshold, the row is positioned relative to the full pavement end rather than the displaced landing threshold, and coordinated with adjacent threshold and edge light circuits so the three systems read as one continuous boundary to the pilot.

Each runway end light is powered from the series circuit via an isolating transformer. The light projects a narrow, uni-directional beam towards the approaching aircraft, using a precision optical system with a reflector and prism. The red colour is achieved through a red filter or dichroic coating. The intensity is controlled by the CCR's current steps, with higher intensities used during low visibility operations. The lights are typically flush-mounted (inset) in the pavement, though elevated versions may be used in some configurations.

Runway end lights are not individually addressable — control is exercised at the loop level, and in most airfield electrical designs the end light row is wired into the same series circuit as the runway edge lights (and frequently the threshold lights too), so the entire runway edge lighting system switches and dims together as one. 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 shared loop to the corresponding fixed current. Every fixture on that loop, whether it is a runway end light, an edge light, or a threshold light, draws from the same current via its own isolating transformer and therefore burns at the same intensity simultaneously — the end light row cannot be commanded independently unless it has been isolated onto its own circuit at the design stage. 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.

The fixture body is a die-cast aluminium alloy housing, anodised or powder-coated for corrosion resistance, with an internal reflector and baffle arrangement that restricts the beam to a uni-directional pattern facing the approach. The red colour is produced by a filtered lens or coloured LED array rather than a dyed housing, so output stays consistent as the fixture ages; the lens itself is toughened glass or high-strength polycarbonate, gasket-sealed with an O-ring to the housing for an IP67/IP68 rating. Since runway end lights sit within a frangibility-sensitive zone, the fixture is almost always an inset (flush) unit, seating into an L-868 base can recessed into the pavement with a wheel-load-rated top plate rather than mounting on a frangible coupling. Internal leads terminate at L-823 primary connectors, sealed for direct burial and continuous immersion, mating to the isolating transformer's secondary in an adjacent base can. Stainless-steel fasteners and a drainage path around the base can complete the assembly, keeping the connector joint clear of standing water.