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AIM

10/12/17

2−1−5

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
red.

FIG 2−1−7

Pulsating Visual Approach Slope Indicator

Above Glide Path

On Glide Path

Below Glide Path

Slightly Below Glide Path

Threshold

PULSATING WHITE

PULSATING RED

STEADY WHITE

STEADY RED

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.

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 is a steady 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

these systems is approximately three−quarter miles.