Runway distance remaining signs are placed on the side of a runway and provide the pilot with information on how much runway is left during takeoff or landing operations. These signs are placed at 1000 ft intervals along the runway is a descending sequential order. Normally, these signs consist of white numerals on a black background,
The FAA recommends that the signs be configured in one of three ways . The preferred method of configuration, and the most economical, is to place double-faced signs on only one side of the runway. In this configuration it is recommended that the signs be placed on the left side of the most frequently used direction of the runway. The signs may be placed on the right side of the runway when necessary due to required runway-taxiway separations or due to conflicts between intersecting runways or taxiways. An alternative method is to provide a set of single-faced signs on either side of the runway to indicate the distance remaining when the runway is used in both directions. The advantage of this configuration is that the distance remaining is more accurately reflected when the runway length is not an even multiple of 1000 ft. Another alternative uses double-faced signs on both sides of the runway. The advantage of this method is that the runway distance is displayed on both sides of the runway in each direction which is an advantage when a sign on one side needs to be omitted because of a clearance conflict. When the runway distance is not an even multiple of 1000 ft, one half of the excess distance is added to the distance on each sign on each runway end. For example, if the runway length available is 8250 ft, the last sign is located at a distance of 1000 plus 125 ft from the end of the runway. A tolerance of ±50 ft is allowed for the placement of runway distance remaining signs. These signs should be illuminated anytime the runway edge lights are illuminated. The recommended sizes and placement of these signs is given in below Table .