- Precision Approach Path Indicator (PAPI).
This system enhances safety by providing beneficial visual approach slope guidance to
assist the pilot of an aircraft in flying a stabilized approach. PAPI has an effective visual
range of approximately 5 miles during the day and up to 20 miles at night. The presence of
objects in the approach area may present a serious hazard if an aircraft descends below the
normal path. PAPI helps the pilot maintain a safe distance above hazardous objects. The
visual aiming point obtained with PAPI reduces the probability of undershoots or
overshoots.
- Location and Spacing
The PAPI is usually located on the left-hand side of the runway at right angles to the runway
center,300 meters beyond the landing threshold. The units are spaced 9 meters apart with the
nearest unit 15 meters from the runway edge.
- Color
Each light unit emits a two-color (red and white) light beam. See Figure 10 - 24 for PAPI
signal presentation as seen from the approaching aircraft.