Index   100 -- Page 101 -- 102

12/10/15                                                                                                              AIM


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


                                                                                                       PULSATING WHITE



                                                                                                       STEADY WHITE
                                                                                  th
                                                                             e Pa
                                                                           d
                                                                      Gli
                                                                 bove            ath
                                                                A
                                                                          i d eP                       STEADY RED
                                                                      G l                       Path
                                                                   On                low  Glide
                                                                               tly Be
                                                                       Sligh
                                                                                        ath
                                                                                Glide P                PULSATING RED
                                                                     Below


                                                                 Threshold


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 ap-                   glide slope. The useful range of the system is about
proach slope indicators normally consist of a single            four miles during the day and up to ten miles at night.
light unit projecting a two-color visual approach               (See FIG 2-1-7.)
path into the final approach area of the runway upon
which the indicator is installed. The on glide path               e. Alignment of Elements Systems. Alignment
indication is a steady white light. The slightly below          of elements systems are installed on some small
glide path indication is a steady red light. If the             general aviation airports and are a low-cost system
aircraft descends further below the glide path, the red         consisting of painted plywood panels, normally black
light starts to pulsate. The above glide path indication        and white or fluorescent orange. Some of these
is a pulsating white light. The pulsating rate increases        systems are lighted for night use. The useful range of
as the aircraft gets further above or below the desired         these systems is approximately three-quarter miles.


Airport Lighting Aids                                                                                               2-1-5