Runway Turn Pad Light for Airfield Ground Lighting

Runway turn pad lights provide continuous visual guidance along a runway turn pad, helping an aircraft complete a turn and align with the runway centreline. A turn pad is a defined pavement area at or near the runway end that allows an aircraft to manoeuvre through a 180-degree turn where required. The lighting should follow the geometry of the marked turn path and be treated as a complete visual-aid system, not simply a light fixture.

ICAO specifies turn-pad lights for continuous guidance on turn pads intended for use in RVR conditions below 350 m, and recommends them for turn pads intended for use at night.

ICAO specifies runway turn-pad lights as fixed, unidirectional green lights, with beam dimensions arranged so that the lights are visible only from aircraft on or approaching the turn pad. Optical directionality is a defining feature, so do not select on colour alone, because the complete optical distribution and viewing geometry must match the approved design.

Under ICAO provisions the lights are normally on the runway turn-pad marking, or offset by not more than 30 cm where a light cannot practicably be on the marking. Longitudinal spacing is not more than 15 m on straight sections and not more than 7.5 m on curved sections. Closer spacing on curves gives a more continuous indication of the aircraft’s changing direction, and the actual fixture positions must come from the approved turn-pad marking and project lighting layout.

No. Turn-pad guidance lights are green and directional, while turn-pad edge lights are blue and define the edge or perimeter. ICAO identifies taxiway edge lights, with blue fixed characteristics, at the edges of turn pads intended for night use. A project may include both systems, and the required combination should be determined from the approved lighting design.

A turn pad light gives continuous guidance through the turn, is typically green and unidirectional, and sits on the turn-pad marking. A taxiway edge light identifies the edge or perimeter, is typically blue and omnidirectional unless the design specifies otherwise, and sits on the turn-pad or taxiway edge. They are not interchangeable.

They are supplied in an inset configuration, where the fixture is installed within the pavement and aligned with the turn-pad marking, and the fixture and housing should be treated as one coordinated installation assembly. A typical inset assembly includes the light fitting, in-pavement housing, optical lens, LED module, sealing gasket, mounting hardware, drainage arrangement, secondary cable, isolating transformer and primary connector. For inset installations, focus on water ingress, drainage, sealing, the pavement interface and mechanical loading.

A typical arrangement is a CCR feeding a primary AGL cable, an isolating transformer, a secondary cable and the turn pad light. Before procurement confirm the CCR current, number of fixtures, fixture electrical load, transformer rating, primary and secondary cable, connector configuration, intensity steps, monitoring arrangement and control-system interface. Poor electrical coordination can cause reduced light output, incorrect intensity, circuit instability, transformer stress, premature fixture failure or monitoring abnormalities.

Check the approved turn-pad marking and geometry, runway centreline and pavement edge, fixture spacing on straight and curved sections, optical direction and beam axis, the aircraft viewing direction, and alignment with the turn-path geometry, as well as the housing and fixture seating, pavement cut-out and level, drainage, sealing and mounting. Commissioning covers circuit continuity, insulation resistance, transformer verification, series-circuit current, CCR operation, intensity steps, monitoring and photometric verification of colour, intensity, optical direction and beam distribution.

A light that is off can come from an open series circuit, light-source failure, transformer failure, connector failure, a secondary cable fault or an internal fixture failure. Low output can come from an incorrect CCR setting, optical contamination, LED degradation, damaged optics or an electrical mismatch. An incorrect colour can come from incorrect fixture configuration, light-source degradation, optical damage, contamination or an incorrect replacement component, and an incorrect direction from incorrect installation or a misoriented optical assembly. Poor curve guidance can come from excessive spacing, incorrect curve alignment, a missing fixture or an incorrect layout.

References include ICAO Annex 14 Vol. I (Chapter 5 on runway turn-pad lights), FAA AC 150/5340-30J, FAA AC 150/5345-46F, DGCA India requirements and the airport-specific AGL specification and approved layout. ICAO adopted Amendment 18 to Annex 14 Vol. I in 2025, with an applicable date of 27 November 2025 for the relevant visual-aid provisions, so check the applicable edition or amendment and the exact FAA fixture classification for each project.

No. An open series circuit driven by a constant-current regulator can produce dangerously high voltage, and opening, cutting or disconnecting any part of an energised circuit can cause serious injury or death. Do not disconnect or reconnect a fixture’s secondary connector while the series circuit is energised, because an open secondary on a series isolating transformer can develop hazardous voltage and damage the transformer. De-energise the circuit at the regulator, apply the site lock-out / tag-out procedure, use the series circuit cut-out switch or an approved isolation device, and work on the movement area only under the airport’s permit-to-work system, with the runway or taxiway closed as required. See the electrical safety warning on this page.