A Monitoring System for PAPI
The Nippon Signal Co., Ltd. 3-3-1, Marunouchi, Chiyoda-ku, Tokyo 100, Japan
One of the facilities at airports is a PAPI (Precision Approach Path Indicator). This is for giving an instruction on the angle of approach to the pilots of an airplane in landing mode by means of light generated from lamps place on the ground. The PAPI light is clearly distinguished between the white color in the upper part and red color in the lower part by means of a high-precision optical system. The PAPI lighting system consists of four lighting devices which are arranged horizontally forming all different elevation angles, and the way the white and red colors are arranged gives information on the angle of approach. For this reason, the lighting devices must have correct elevation angles and project light with pre-set brightness. A system has been developed for monitoring PAPI light by directly receiving light from the lighting devices by means of light receivers placed forward of the lighting devices and focusing and transmitting the light with optical fibers and checking the light by means of amorphous Si color sensor. This paper will introduce this system.