All runways licensed for night use must have lighting which at least defines the extent of the runway. This is referred to as Edge Lighting, Threshold Lighting and Runway End Lighting. Other types of lighting may also be provided.
ICAO guidance requires that runway lighting shall not be operated if a runway is not in use for landing, take-off or taxiing purposes, unless such operation is required for runway inspection or maintenance purposes. ATC are required to use whatever means are available to them to ensure that they are aware of any lighting system unserviceability so that appropriate notification action can be taken.
Minimum Runway Lighting
- Runway Edge Lights are omni-directional and are located along or just beyond the edges of the area declared for use as the runway as defined by edge markings and are white subject to certain specific exceptions. The area defined may not necessarily be the maximum width of the paved runway surface. The lights may be either elevated or embedded in the surface. If a landing threshold is displaced, but the pre-landing threshold area is available for take off, then the edge lights between the beginning of the runway surface and the displaced threshold will be split so as to show red up to the landing threshold whilst still showing white after that point. If a runway ‘starter extension’ is provided which is narrower than its associated runway, then blue edge lighting may be used to mark its edges.
- Runway Threshold Lights are provided in a line along the landing threshold at the touchdown end of a runway and define the beginning of the declared Landing Distances. They are green and can only be seen from the approach.
- Runway End Lights are provided in a line along the end of the runway available for use. They are red and can only be seen in the direction of runway use.
Supplementary Runway Lighting
Various other forms of runway lighting may also be provided, especially if the runway is used for aircraft movements in less than ILS Cat 1 conditions, which require both Low Visibility Procedures (LVP) and, in most cases, specific forms of additional lighting.
- Runway Exit taxiways may be indicated by substitution of one or two of the white runway edge lights with blue ones.
- Stopway Lighting may be used to show the extent of a stopway beyond the designated end of a runway. Red unidirectional edge lights visible only in the direction of runway use are provided at intervals until a further transverse line which marks` the end of the stopway.
- Runway Centreline Lighting may be provided in which case it will extend for the full length of the runway, It will be white except in the event that colour coding is provided in order to indicate the approaching end of the runway. Such colour coded centreline lighting consists of alternating red and white lights beginning at 900 metres from the runway end and these change to continuous red lights for the last 300 metres of the runway.
- Touchdown Zone (TDZ) Lighting must be provided on runways available for use in low visibility conditions so as to provide enhanced identification of the touchdown area. The method of provision is specified in ICAO Annex14 Volume 1 ‘Aerodrome Design and Operations’ and the lighting must extend from the landing threshold for either 900 metres or to the midpoint of the runway, whichever is the least.
- Rapid Exit Taxiway Indicator Lights (RETILs) may be provided to indicate the distance to go to the nearest rapid exit taxiway. In low visibility conditions, RETILs provide useful situational awareness cues to assist in appropriate rates of deceleration and to allow flight crew to concentrate on keeping the aircraft on the runway centre line during the landing roll. They usually consist of six yellow lights adjacent to the runway centreline, configured as a three - two - one sequence spaced 100 metres apart with the single light positioned at 100 metres from the start of the turn for the rapid exit taxiway.
- Caution Zone Lighting may be provided on ILS-equipped runways which do not have centreline lighting. It is provided by replacing the usual white edge lights with yellow` ones for the lesser of the last 600 metres or last one third of the lighted runway length available to provide a visual warning the approaching runway end.
- Landing Threshold Wing Bars, which are green but may take various detail forms, are sometimes provided if it is considered that the threshold needs accentuating.
It must be possible to adjust the intensity of runway lighting so as to be suitable for the full range of horizontal visibility and ambient light in which use of the runway is intended. It must also be compatible with the intensity set for the nearest section of the approach lighting system, when such a system is also provided. Flight crew can be expected to request ATC to adjust runway lighting intensity in order to ensure that, for their particular case, it is of sufficient intensity to be useful but not so bright as to hinder overall visual clarity. Whilst automatic or careful manual control of lighting intensity based upon the degree of available natural light will produce a generally acceptable lighting intensity, the intensity preferred by a particular crew may differ because of variation in pilot eye height above the runway surface (broadly proportional to aircraft size) or because of the effect of the reflective properties of moisture particles when forward visibility is restricted.
Information on Runway Lighting at an Airport
A detailed description of the runway lighting system at each licensed airport must be provided in the State AIPs. It must include details, including colour, intensity and extent, of:
- the runway threshold lights and any wing bars
- the runway edge lights
- the runway end lights and any wing bars
- any runway touchdown zone lights
- any runway centre line lights
- any stopway lights
Equivalent information will be found on aerodrome charts in proprietary ‘Flight Guides’ provided by aircraft operators for flight deck use.