Author: D. M. FinchPublisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 66
Book Description
Using a specially developed photometric method, the visibility of a runway lighting system was studied under various conditions of visual range and background brightness. The method is based on measurement of a defined quantity, C sub d, called photometer detection contrast, and depends on the correlation of this quantity with subjective visibility. All tests were performed in the FAA Fog Chamber at 1/10 scale. Photometric data for the runway lights were obtained in daytime and nighttime visual ranges of 1200, 900, and 700 ft, and maximum visibility distances for various portions of the lighting system were then determined on the basis of an assumed value of .06 for the minimum usable C sub d. Based on the number of lighting elements that would be visible to a pilot under the various test conditions studied, it was concluded that the lighting system would become but marginally effective for visual guidance in a daytime fog of 900-ft visual range and background brightness of about 50-600 fL. The same would hold true for a nighttime fog of 700-ft visual range. In a daytime visual range of 700 ft, the system would no longer provide effective visual guidance. (Author).