The following civil airport imaginary surfaces shall be
established with relation to the airport and to each runway. The size of each
imaginary surface shall be 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 shall be
determined by the most precise approach existing or planned for that runway
end.
(1) Horizontal surface shall be a
horizontal plane one hundred fifty feet above the established airport
elevation, the perimeter of which shall be constructed by swinging arcs of
specified radii from the center of each end of the primary surface of each
runway of each airport and connecting the adjacent ares by lines tangent to
those arcs. The radius of each arc shall be:
(A) five thousand feet, for all runways
designated as utility or visual;
(B) Ten thousand feet for all other runways.
The radius of the arc specified for each end of a runway
shall have the same arithmetical value. That value shall be the highest
determined for either end of the runway. When a five thousand-foot arc is
encompassed by tangents connecting two adjacent ten thousand-foot arcs, the
five thousand-foot arc shall be disregarded on the construction of the
perimeter of the horizontal surface.
(2) Conical surface shall be a surface
extending outward and upward from the periphery of the horizontal surface at a
slope of twenty to one for a horizontal distance of four thousand
feet.
(3) Primary surface shall be
a surface longitudinally centered on a runway. When the runway has a specially
prepared hard surface, the primary surface shall extend two hundred feet beyond
each end of that runway; but when the runway has no specially prepared hard
surface or planned hard surface, the primary surface shall end at each end of
that runway. The elevation of any point on the primary surface shall be the
same as the elevation of the nearest point on the runway centerline.
The width of a primary surface shall be:
(A) Two hundred fifty feet for Utility
runways having only visual approaches.
(B) Five hundred feet for utility runways
having nonprecision instrument approaches.
(C) For other than utility runways, the width
shall be:
(i) Five hundred feet for visual
runways having, only visual approaches.
(ii) Five hundred feet for nonprecision
instrument runways having visibility minimums greater than three-fourths
statute mile.
(iii) One thousand
feet for a nonprecision instrument runway having a nonprecision instrument
approach with a visibility minimum as low as three-fourths of a statute mile,
and for precision instrument runways. The width of the primary surface of a
runway shall be that width prescribed in this section for the most precise
approach existing or planned for either end of that runway.
(4) Approach surface
shall be surface longitudinally centered on the extended runway centerline and
extending outward and upward from each end of the primary surface. An approach
surface shall be applied to each end of each runway based upon the type of
approach available or planned for that runway end.
(A) The inner edge of the approach surface
shall be the same width as the primary surface and shall expand uniformly to a
width of:
(i) One thousand two hundred fifty
feet for that end of a utility runway with only visual approaches;
(ii) One thousand five hundred feet for that
end of a runway other than a utility runway with only visual
approaches;
(iii) Two thousand feet
for that end of utility runway with a nonprecision instrument
approach;
(iv) Three thousand five
hundred feet for that end of a nonprecision instrument runway other than
utility having visibility minimums greater than three-fourths of a statute
mile;
(v) Four thousand feet for
that end of a nonprecision instrument runway, other than utility, having a
nonprecision instrument approach with visibility minimums as low as
three-fourths statute mile; and
(vi) Sixteen thousand feet for precision
instrument runways.
(B)
The approach surface shall extend for a horizontal distance of:
(i) Five thousand feet at a slope of twenty
to one for all utility and visual runways;
(ii) Ten thousand feet at a slope of
thirty-four to one for all nonprecision instrument runways other than utility;
and
(iii) Ten thousand feet at a
slope of fifty to one with an additional forty thousand feet at a slope of
forty to one for all precision instrument runways.
(C) The outer width of an approach surface to
an end of a runway shall be that width prescribed in this paragraph (4) for the
most precise approach existing or planned for that runway end.
(5) Transitional surfaces shall
extend outward and upward at right angles to the runway centerline and the
runway centerline extended at a slope of seven to one from the sides of the
primary surface and from the sides of the approach surfaces. Transitional
surfaces for those portions of the precise approach surface which project
through and beyond the limits of the conical surface shall extend a distance of
five thousand feet measured horizontally from the edge of the approach surface
and at right angles to the runway centerline.
