AIM

4/20/23

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Airport Lighting Aids

FIG 2

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Pulsating Visual Approach Slope Indicator

NOTE

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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

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Alignment of Elements

Below Glide Path

On Glide Path

Above Glide Path

d. Pulsating Systems.

Pulsating visual approach slope indicators normally consist of a single light unit

projecting a two

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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

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7.)

e. Alignment of Elements Systems.

Alignment of elements systems are installed on some small general

aviation airports and are a low

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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 these systems is
approximately three

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quarter miles. To use the system the pilot positions the aircraft so the elements are in

alignment. The glide path indications are shown in FIG 2

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8.