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Airport Lighting Aids

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

FIG 2−1−7

Pulsating Visual Approach Slope Indicator


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.

FIG 2−1−8

Alignment of Elements

Below Glide Path

On Glide Path

Above Glide Path

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