Aircraft illumination

GENERALLY little use is found for auxiliary lighting during daytime operation of aircraft, as the daylight is all that is necessary for adequate lighting of the cabin, cockpit, and landing and take-off fields. Artificial light may be required in order to perform successfully the duties of aircraft operation during about 60 per cent of the 24-hour period. Though normal daylight may be effective for more than 50 per cent of the day throughout the year, actually artificial lighting is required at the dawn and dusk periods inasmuch as the normal amount of daylight is not adequate. It is obvious of course that it is highly impractical to provide over-all lighting to duplicate daylight. Therefore, localized artificial lighting is the best approach to the problem. With proper illumination in the cockpit, however, normal operating conditions are carried out equivalent to those of daylight hours. Artificial lighting is definitely needed so that all functions can be accomplished without delay during the hours of darkness.