UFC 3-535-01
17 November 2005
12-2.2.5
AC 150/5340-23. Supplemental Wind Cones describes criteria for the
location and performance of supplemental wind cones.
12-2.2.6
AC 150/5340-24. Runway and Taxiway Edge Lighting System describes
standards for the design, installation, and maintenance of runway and taxiway edge
lighting.
12-3
SITING PAPI
12-3.1
Considerations
Siting a PAPI requires consideration of the following: if there is or will be an ILS glide
slope, the established glide path (aiming angle, typically 3 degrees), the threshold
crossing height (TCH) for the selected aircraft height group, the runway gradient
(longitudinal slope) from the threshold to the PAPI location, and other factors.
12-3.1.1
With an ILS glide slope, the PAPI is located the same distance from the
runway threshold so that the elevation of the lens center of the light units intercepts the
runway at the same location as the virtual source of the ILS glide slope, within a
tolerance of 10 meters (30 feet), and is aimed at the same angle as the ILS glide
slope. The virtual source is the Runway Point of Intercept (RPI), where the glide path
intercepts the ground elevation along the runway centerline. PAPI location considers the
light beam, where the elevation of the lens center of the PAPI light units should intercept
the ground elevation along the runway centerline (within tolerance). For aircraft in height
group 4 (Table 3-3) for Army airfields only, the PAPI is sited at the RPI plus an
additional 90 meters (300 feet), +15 meters 0 meters (+50 feet 0 feet), from
threshold.
12-3.1.2
If there is no ILS glide slope, the PAPI is sited as shown in Figure 12-6.
First determine the following:
12-3.1.2.1 Glide Path
Typically this is 3 degrees, but it may vary at some locations.
12-3.1.2.2 Threshold Crossing Height (TCH)
See Table 3-3. For the Air Force, the TCH is based on the most predominant aircraft
using the runway (the major command will make this determination). For the Army, the
TCH is based on the most demanding aircraft height group expected to use the runway
(the aviation community will coordinate with USAASA for this determination).
12-3.1.2.3 Runway Gradient
This may be available from record drawings, or determined by field survey. Usually the
grade is given as a percent representing the vertical elevation difference over a
longitudinal distance (threshold through approximate PAPI location). For example, a 1
percent grade represents a 0.3 meter (12 inch) height difference over a 30 meter (100
feet) length. This is converted to an angle in degrees, α, using the relationship: tan α =
percent grade (expressed as decimal). With this relationship, a grade of 1 percent
represents a runway slope of 0.573 degrees (from the horizontal).
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