Section 77.19

14 CFR Ch. I (1-1-19 Edition)

flight altitude within that area or segment to be less than the required obstacle clearance.
(4) A height within an en route obstacle clearance area, including turn and
termination areas, of a Federal Airway
or approved off-airway route, that
would increase the minimum obstacle
clearance altitude.
(5) The surface of a takeoff and landing area of an airport or any imaginary
surface established under Section 77.19, 77.21,
or 77.23. However, no part of the takeoff or landing area itself will be considered an obstruction.
(b) Except for traverse ways on or
near an airport with an operative
ground traffic control service furnished
by an airport traffic control tower or
by the airport management and coordinated with the air traffic control service, the standards of paragraph (a) of
this section apply to traverse ways
used or to be used for the passage of
mobile objects only after the heights of
these traverse ways are increased by:
(1) 17 feet for an Interstate Highway
that is part of the National System of
Military and Interstate Highways
where overcrossings are designed for a
minimum of 17 feet vertical distance.
(2) 15 feet for any other public roadway.
(3) 10 feet or the height of the highest
mobile object that would normally traverse the road, whichever is greater,
for a private road.
(4) 23 feet for a railroad.
(5) For a waterway or any other traverse way not previously mentioned,
an amount equal to the height of the
highest mobile object that would normally traverse it.

kpayne on VMOFRWIN702 with $$_JOB

Section 77.19 Civil
faces.

airport

imaginary

sur-

The following civil airport imaginary
surfaces are established with relation
to the airport and to each runway. The
size of each such imaginary surface is
based on the category of each runway
according to the type of approach
available or planned for that runway.
The slope and dimensions of the approach surface applied to each end of a
runway are determined by the most
precise approach procedure existing or
planned for that runway end.

(a) Horizontal surface. A horizontal
plane 150 feet above the established airport elevation, the perimeter of which
is constructed by SW.inging arcs of a
specified radii from the center of each
end of the primary surface of each runway of each airport and connecting the
adjacent arcs by lines tangent to those
arcs. The radius of each arc is:
(1) 5,000 feet for all runways designated as utility or visual;
(2) 10,000 feet for all other runways.
The radius of the arc specified for each
end of a runway will have the same arithmetical value. That value will be
the highest determined for either end
of the runway. When a 5,000-foot arc is
encompassed by tangents connecting
two adjacent 10,000-foot arcs, the 5,000foot arc shall be disregarded on the
construction of the perimeter of the
horizontal surface.
(b) Conical surface. A surface extending outward and upward from the periphery of the horizontal surface at a
slope of 20 to 1 for a horizontal distance
of 4,000 feet.
(c) Primary surface. A surface longitudinally centered on a runway. When
the runway has a specially prepared
hard surface, the primary surface extends 200 feet beyond each end of that
runway; but when the runway has no
specially prepared hard surface, the
primary surface ends at each end of
that runway. The elevation of any
point on the primary surface is the
same as the elevation of the nearest
point on the runway centerline. The
width of the primary surface is:
(1) 250 feet for utility runways having
only visual approaches.
(2) 500 feet for utility runways having
non-precision instrument approaches.
(3) For other than utility runways,
the width is:
(i) 500 feet for visual runways having
only visual approaches.
(ii) 500 feet for non-precision instrument runways having visibility minimums greater than three-fourths statute mile.
(iii) 1,000 feet for a non-precision instrument runway having a non-precision instrument approach with visibility minimums as low as threefourths of a statute mile, and for precision instrument runways.

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