length. Runway edge lights are spaced a maximum of 200 feet apart. Runway edge
lights are bidirectional white lights. The last 2,000 feet of the runway or one-half of the
runway length, whichever is less, is displayed by the lights as aviation yellow on
instrument runways. Except at intersections where semiflush runway edge lights are
used to maintain uniform spacing or within the area of the arresting gear tape sweep,
runway edge lights should be elevated.
Threshold lights are installed so that approaching aircraft can positively identify the
beginning of the operational runway surface at night or during periods of reduced
visibility. Threshold lights are installed in a straight line at the end of each runway
perpendicular to the runway centerline. The outboard lights are unidirectional (toward
the aircraft approach path) green lights. The inboard lights are green but may be
bidirectional with red beams (toward the runway) for runway end lights. Threshold lights
are connected to and from an integral part of the runway edge light circuit.
Runway End Identification Lights
Runway end identification (identifier) lights (REIL) provide the pilot with rapid, positive
identification of the runway threshold during an approach for landing. REILs assist pilots
in making landings in VFR conditions and in nonprecision instrument approaches in IFR
REILs consist of flashing light fixtures (strobe lights), one located on each side of the
runway threshold. REILs can be either uni- or omnidirectional and flash at a rate of 90
(plus or minus 30) flashes per minute. These lights are installed in line with the
threshold lights and are a minimum of 40 feet from the edge of taxiways and runways.
REILs are operated when the associated runway edge lights are lighted.
Runway Centerline Lights and Touchdown Zone Lights
Runway Centerline Lights (RCL) provide visual aid to help the pilot keep the aircraft
centered on the runway during takeoff and after landing at night or in reduced visibility
conditions. RCL, where installed, consist of a single row of lights at uniform intervals of
25 feet apart (50 feet for FAA type lights) along the centerline of the runway to provide a
continuous lighting reference from threshold to threshold of the runway. The lights are
semiflush and bidirectional. Centerline lighting may be installed on primary and
secondary runways. Runway centerline lights are white from the threshold to a point
3,000 feet from the runway end. They alternate colors of red and white from 3,000 feet
to 1,000 feet from the runway end and are red in color from 1,000 feet to the runway
end. The intensity should be the same as that of the high-intensity runway lights.
Touchdown zone lights (TDZL) provide visual guidance during final approach and
landing and indicate the portion of the runway used for touchdown. These are semiflush
white unidirectional lights that are located on each side of the runway centerline in a line