UFC 3-535-01
17 November 2005
A light plane or planes in which the lights of the system are located, are used for
determining obstruction clearances of the approach lights. The side boundaries of the
light plane are 60 meters (200 feet) on each side of the runway centerline extended.
The end boundaries are at the runway threshold and at 60 meters (200 feet) before the
start of the approach light system. All lines in the plane perpendicular to the centerline
are level. The ideal light plane (Figure 3-3) is a single horizontal plane through the
runway threshold. If the 300 meters (1,000 feet) of the runway at the threshold end is
sloped, the first 100 meters (300 feet) of the paved or stabilized area of the approach
zone and the light plane for this area must continue with the same slope. The final 235
meters (700 feet) of the paved or stabilized area may have a slope of not more than 1.5
percent up or down. From the 300 meter (1,000 foot) crossbar to the beginning of the
approach light system, the preferred light plane is horizontal and includes the 1,000-foot
crossbar lights. If the clearance of obstructions or terrain prohibits using a horizontal
light plane, this plane may be sloped. The slope of this plane must not exceed 2 percent
up or 1.5 percent down. The preferred light plane in the area beyond the 300 meter
(1,000 foot) crossbar is a single plane, but changes in the slope of the plane are
permitted. All light planes start and end at a light station and contain not less than three
light stations.
Figure 3-3. Light Plane Elevation Limits
300M
600M
(1000FT)
(2000FT)
APPROACH LIGHTS NOT TO BE
MOUNTED ABOVE THIS LINE
17M
(55FT)
+2.0% MAX.
+1.5% MAX.
MAX.
RUNWAY
5M (15FT) MAX.
LEVEL
5M (15FT) MAX.
13M
(45FT)
-1.5% MAX.
-1.5% MAX.
MAX.
THRESHOLD
APPROACH LIGHTS NOT TO BE
MOUNTED BELOW THIS LINE
NOTE: THE BOUNDARIES OF THE LIGHT PLANES ARE THE RUNWAY THRESHOLD, 60M (200FT)
AHEAD OF THE END LIGHT STATION, AND 60M (200FT) EACH SIDE OF CENTERLINE.
3-1.4.4
Light Plane Obstructions
No objects may penetrate the light plane except for ILS components and components of
airfield lighting systems which are fixed by their function. These components must not
interfere with the pilot's view of the approach lights when on a normal approach and
must be obstruction lighted. For clearance purposes, all roads, vehicle parking areas
and railroads are considered as vertical solid objects. The required clearance above
railroads is 7.5 meters (23 feet) and above interstate highways is 6 meters (17 feet).
The clearance required above other public roads and parking lots is 5 meters (15 feet).
The clearance above private and military roads is 3 meters (10 feet). Airfield service
roads, where traffic is controlled, are not considered as obstructions. Control of the
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