UFC 3-535-01
17 November 2005
ellipse (an "isocandela curve" of same values), although for some fixtures the
requirements may be rectangular or simply numerical. Examples are shown in Figure 4-
2 (high intensity white or "clear" runway edge light) and Figure 4-5 (high intensity green
threshold light), which illustrate the photometric requirements at highest intensity step
for the type of light.
15-16.2
The wattage of lamp(s) and other light fixture characteristics are
determined by each manufacturer in order to meet the photometric requirements for a
particular type of light, which are tested and certified for compliance with the
requirements. A light fixture design is based on achieving the required photometric
output at full rated lamp wattages, in fixtures connected on a 6.6 amperes series lighting
circuit. The lower current steps of series lighting circuits are based on achieving lower
levels of light output.
15-16.3
Figure 15-6 shows a typical photometric requirements or "isocandela
curves" for a runway edge light. The ellipses are defined by degree of angle from the
center along vertical and horizontal axes. The requirements for the inner ellipse, or
"main beam," are:
15-16.3.1
Minimum average intensity (10,000 cd, aviation white in the example).
15-16.3.2. Minimum intensity no less than 50 percent of the minimum average
intensity (5,000 cd in this case).
15-16.3.3
Maximum intensity should not exceed 1.5 times the actual average
intensity.
For the outer ellipse, the minimum intensity should not be less than 10 percent of
the minimum average intensity (1,000 cd in the example).
Figure 15-6. Photometric Isocandela Curves
MAIN BEAM ELLIPSE
- MIN. AVERAGE OF MAIN BEAM INSIDE CONTOUR
(10,000cd for RW EDGE LIGHT)
- AT CONTOUR, MIN. 50% OF MIN. AVERAGE
o
6
- MAX. INTENSITY < 1.5 OF MIN. ACTUAL AVERAGE
o
4
OUTER ELLIPSE
50%
- AT CONTOUR, MIN. 10% OF MIN. AVERAGE
OF MAIN BEAM
10%
o
2
CENTER OF AIM
100%
o
o
o
o
o
o
o
o
2
8
6
4
2
4
6
8
NOTE: PHOTOMETRIC CURVES SHOWN
o
2
ARE FOR HIGH INTENSITY RW EDGE LIGHTS.
o
THE MAIN BEAM IS AIMED 4 UP FROM
o
HORIZONTAL, WITH 3.5 TOE-IN FROM
o
4
PARALLEL WITH RW CENTERLINE.
o
6
268
Previous Page
