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2. When the aircraft descends from green to red, the pilot may see a dark amber color during the transition from green to red. 

<img src='content_image/521061.jpg'>

## NOTE − 

Since the PVASI consists of a single light source which could possibly be confused with other light sources, pilots should exercise care to properly locate and identify the light signal. 

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d. Pulsating Systems. Pulsating visual ap- proach slope indicators normally consist of a single light unit projecting a two − color visual approach path into the final approach area of the runway upon which the indicator is installed. The on glide path indication may be a steady white light or alternating RED and WHITE light. The slightly below glide path indication is a steady red light. If the aircraft descends further below the glide path, the red light starts to pulsate. The above glide path indication is a pulsating white light. The pulsating rate increases as the aircraft 

gets further above or below the desired glide slope. The useful range of the system is about four miles during the day and up to ten miles at night. (See FIG 2 − 1 − 7.) 

e. Alignment of Elements Systems. Alignment of elements systems are installed on some small general aviation airports and are a low − cost system consisting of painted plywood panels, normally black and white or fluorescent orange. Some of these systems are lighted for night use. The useful range of 

