d. Teardrop pattern. Spherical shaped water
allows the weight and wind loading factors to be
storage tanks with a single circular standpipe support
(2) Size and color. The diameter of the
may be colored in a teardrop stripped pattern, as shown
markers should not be less than 20 inches and should be
in figure 7-4. The tank should be colored to show
colored aviation orange.
alternate stripes of aviation surface orange and white.
b. Flag markers. Flags may be used to mark
The stripes should extend from the top center of the tank
obstructions when it has been determined that the use of
to its supporting standpipe.
(1) Width of stripes. The width of the
coloring or spherical markers is technically impracticable.
Flag markers should be
stripes should be equal and the width of each stripe at
displayed around, on top of the obstruction or around its
the greatest girth of the tank should not be less than 5
highest edge. When flags are used to mark extensive
feet nor more than 15 feet.
(2) Community name. If it is desirable to
obstructions or closely grouped obstructions, they should
be displayed approximately 50 feet apart.
paint the name of the community on the side of the tank,
(2) Shape. Flags should be rectangular in
the stripe pattern may be broken to serve this purpose.
shape and have stiffeners to keep them from drooping in
This open area should have a maximum height of 3 feet.
calm wind. The flag stakes should be of such strength
and height that they will support the flags free of the
Markers. Markers should be used to mark
ground, vegetation or nearby surfaces.
obstructions when it has been determined that it is
(3) Color patterns. Flags should be in one
impracticable to mark such obstructions by painting.
of the following patterns:
Markers may also be used in addition to aviation surface
(a) Solid color.
orange and white colors when it has been determined
orange not less than 2 feet on a side.
that such markings should be used to provide protection
(b) Orange and white. Two triangular
for air commerce.
They should be displayed in
sections, one of aviation surface orange and the other of
conspicuous positions on or adjacent to the obstructions
aviation surface white, combined to form a rectangle not
so as to retain the general definition of the obstruction.
less than 2 feet on a side.
They should be recognizable in clear air from a distance
(c) Checkerboard. A checkerboard
of at least 1,000 feet in all directions from which an
pattern of aviation surface orange and aviation surface
aircraft is likely to approach. They should be distinctively
white squares, each 1 foot plus or minus 10 percent on a
shaped so they are not mistaken for markers that are
side, combined to form a rectangle not less than 3 feet
used to convey other information. The shape should be
on a side.
such that the hazard they mark is not increased.
a. Spherical markers. Spherical markers are
normally displayed on overhead wires. Markers may be
7-10. Special markings. In addition to the marking
of another shape, provided the projected area of such
recommendations included herein other documents
markers will not be less than that presented by a
contain appropriate guidelines.
a. Vehicles. Advisory Circular 150/5210-5,
(1) Display. At least one such marker
Painting, Marking and Lighting of Vehicles Used on an
should be displayed at equal intervals for each 150 feet
Airport, contains provisions for marking vehicles
or fraction thereof, of the overall length of the overhead
customarily used on landing areas.
line and not lower than the highest wire. The top 5 feet
b. FAA facilities. Obstruction marking for FAA
of the poles and towers to which overhead wires or guy
facilities shall conform to FAA Drawing Number D-5480,
wires are attached will be marked.
referenced in Federal Aviation Agency Standard, FAA-
between markers may be increased to not more than
STD-003, Paint Systems for Structures.
600 feet when the overhead wires are located more than
c. Unusual complexities. The FAA may also
15,000 feet from the nearest landing area. Where there
recommend appropriate marking in an area where
is more than one overhead wire on which the spheres
obstructions are so grouped as to present a common
can be installed, the spheres may be installed alternately
hazard to air commerce.
along each wire as long as the distance between
adjacent spheres meets the spacing standard. This