4/20/23 

AIM 

FIG 2

−

1

−

7 

Pulsating Visual Approach Slope Indicator 

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 

Above Glide Path 

On Glide Path 

Below Glide Path 

d.  Pulsating Systems. 

Pulsating visual approach 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 these systems is 

approximately three

−

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

−

1

−

8. 

Airport Lighting Aids 

2

−

1

−

5