The U.S. Federal Aviation Administration (FAA), has minimum lighting standards for runways that operate at night. The lights must define the limits of the runway. The International Civil Aviation Organization (ICAO) requires runway lighting, as well as other visual aids, to be understandable by pilots from all over the world. Minimum runway lighting includes edge lighting, threshold lighting and end lighting. The airport may provide supplementary lighting, including runway end identifier lights, centerline lights, and touchdown zone lights.
Runway edge lights are all of an equal brightness aviation white. Airports must install them as close to the edge of the runway paving as possible, and within 10 feet of the edge. There must be a row of edge lights on each side of the runway, runnings its entire length and equidistant from the runway's center line. The lights must have uniform spacing between them, with a maximum separating distance of 200 feet.
Runway threshold lights are green, installed to be seen only from the approach side of the runway. They mark the touchdown end of the runway and are the beginning point for the runway's declared landing distance available (LDA).
Runway end lights are red and are installed so that they can only be seen from the direction of the approach area.
For runways surrounded by a large amount of other lighting, or which have little contrast with the surrounding terrain, airports may also install runway end identifier lights (REIL).These are two synchronized flashing lights, one positioned at each corner of the end of the runway.There may also be lights indicating the centerline of the runway. Centerline lights are aviation white unless used to indicate the direction of approach. In that case, the lights are alternately red and white until the final 1,000 feet of the runway, where they are all red. Runways used during low visibility conditions must have touchdown zone (TDZ) lights. They provide pilots with an enhanced marker of the TDZ and consist of rows of aviation white lights, three across, on either side of the runway centerline for 2,700 feet or to the midpoint of the runway, whichever is shorter.
