Retro-Reflective Markers as Taxiway Visual Aids

An investigation was conducted to determine the usefulness of retro-reflective markers to aid pilots in identifying the edges of taxiways. Retro-reflective markers were installed on the edges of two intersecting taxiways and the corresponding fillets.

Field observations were made for comparisons among a variety of retro-reflective markers. Laboratory measurements of brightness were made of a number of selected markers. A questionnaire was used to collect pilot observations during operational tests.

While intensity of the aircraft light and height of the observer above the surface were factors in the observed brightness of retroreflective markers, the major factor was the angle formed by the light source, the reflector, and the observer's eye. The smaller the angle the brighter the reflector appeared. It was determined that on a VFR night, blue retro-reflectors were usable to distances of 1, 000 feet and more, when illuminated by typical landing lights at typical locations on the aircraft. A study was recommended to optimize location of the aircraft landing and taxi lights. Greatly improved operational use of retro-reflectors could result.