Taxiway/runway intersection signs (TRIS) are used to control the surface movements Of aircraft at aerodromes. In order to improve the visual performance of a conventional transilluminated TRIS, fibre optics may he used tot add self-luminous lightpoints to the legends. In this study photometric measurements were carried out for evaluating the efficacy of the fibre optics. The luminance ratio of the legend and background, with the fibre optics off, is 1:4.61 and does not comply with the minimum ratio of 1:5 prescribed by the ICAO. With the fibre optics activated this ratio is 1:84 which is more than the maximum ratio of 1:10 prescribed by the ICAO. By using fibre optics the sign luminance becomes strongly angle dependent, but this may not necessarily have an adverse effect on its functionality. The average luminance of the characters varied over factor 2.6. This variance can be minimised by striving for a constant lightpoint density over the areas of the legends. Only the white colour of the backlighted legend does not meet the ICAO recommendations for the colour co-ordinates. To enhance conspicuousness of the red background it is recommended to add one or two rows of red light points along the outline of the background. To determine the optimal luminance and layout of the sign additional psychophysical research is needed.
Abstract