UFC 3-535-01
17 November 2005
level. This may require locating the light units farther from the runway edge to ensure
adequate clearance for the most critical aircraft. If the light beams are higher than the
allowable tolerance, with respect to the elevation of the runway centerline (raising the
TCH for the visual glide path), the PAPI may be relocated closer to the threshold to
maintain the RRP and TCH.
12-3.1.4.4 The cross slope at the preliminary RRP location may result in the light
units sitting too high or too low with respect to the runway centerline elevation. In such
cases, the PAPI may be relocated closer to or farther from the threshold in order to
maintain the RRP and TCH and remain within tolerance.
12-3.2
Other Dimensions and Tolerances
12-3.2.1
Distance from Runway Edge
Install the inboard PAPI light unit no closer than 15 meters, +3 meters 0 meters (50
feet, +10 feet 0 feet) from the runway edge, or from the edge of other runways or
taxiways.
12-3.2.2
Separation Between Light Units
Provide lateral separation of 9 meters (30 feet) between light units. This may be
reduced to no less than 6 meters (20 feet) if warranted by conditions. The distance
between light units must be equal and not vary by more than 0.3 meters (1 foot).
12-3.2.3
Azimuthal Aiming
Aim each light unit towards the approach zone on a line parallel to the runway
centerline, within a tolerance of 0.5 degree.
12-3.2.4
Mounting Height Tolerance
The beam centers of the four light units must be within 2.5 centimeters (1 inch) of a
horizontal plane. This plane must be within 0.3 meters (1 foot) of the elevation of the
runway centerline at the intercept point of the visual glide path with the runway (RRP),
except for adjustments under conditions in paragraph 12-3.1.4, items 3 and 4.
12-3.2.5
Tolerance Along Line Perpendicular to Runway
The front face of each light unit in a bar must be located on a line perpendicular to the
runway centerline within a tolerance of 15 centimeters (6 inches).
12-3.2.6
Vertical Aiming of Light Beams
For 4-box L-880 PAPI, the units are aimed as shown in Table 12-3.
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