"The effects of pure red and low color temperature white flood lighting upon completely dark adapted visual thresholds have been determined. The red light was adjusted to brightness levels which pilots have been found to use as the minimal, normal, and maximal levels for night flying. For each brightness level of the red light, a brightness was found for the low color temperature white light at which aircraft instruments were equally legible under the two lighting systems. Both a simulated instrument panel and a pure white panel were used as viewing panels. Six subjects were tested under each lighting condition. A higher brightness proved necessary with the low color temperature white light than with the pure red light in order to attain equal legibility of instruments. Both lighting systems at all brightness levels caused small increases in visual thresholds above the completely dark adapted state. When the simulated instrument panel was illuminated at the normal brightness level, thresholds after viewing low color temperature white light were 0.15 log micro-microlamberts above thresholds after viewing pure red light. This value defines the approximate sacrifice in dark adaptation which would be made if white lights, operated at low voltage, were substituted for red lights in flood lighting aircraft instruments. The white lighting would also be more visible to dark adapted enemy observers. However, the white lighting system would make colors in the cockpit appear more natural, which would facilitate such tasks as map reading. When operated at normal voltage, the white lighting system could also provide high intensity illumination for special purposes such as thunderstorm flying, very high altitude daytime flight, and simulated instrument flying with the amber hood and blue goggles."--Abstract.