EXTRACT OF FEDERAL AVIATION REGULATION PART 77,
OBJECTS AFFECTING NAVIGABLE AIRSPACE
The following paragraphs are excerpted from Federal Aviation Regulations, Part 77, Objects
Affecting Navigable Airspace:
77.13 Construction or alteration requiring notice.
(a) Except as provided in 77.15, each sponsor who proposes any of the following construction or
alteration shall notify the Administrator in the form and manner prescribed in 77.17:
(1) Any construction or alteration of more than 200 feet [60.96 m] in height above the ground
level at its site.
(2) Any construction or alteration of greater height than an imaginary surface extending outward
and upward at one of the following slopes:
(i) 100 to 1 for a horizontal distance of 20,000 feet [6 096.00 m] from the nearest point of
the nearest runway of each airport specified in subparagraph (5) of this paragraph with at least one runway
more than 3,200 feet [975.36 m] in actual length, excluding heliports.
(ii) 50 to 1 for a horizontal distance of 10,000 feet 3 048.00 m] from the nearest point of the
nearest runway of each airport specified in subparagraph (5) of this paragraph with its longest runway no
more than 3,200 feet [975.36 m ] in actual length, excluding heliports.
(iii) 25 to 1 for a horizontal distance of 5,000 feet [1 524.00 m ] from the nearest point of
the nearest landing and takeoff area of each heliport specified in subparagraph (5) of this paragraph.
(3) Any highway, railroad, or other traverse way for mobile objects, of a height which, if
adjusted upward 17 feet [5.18 m ] 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 [5.18 m ] vertical
distance, 15 feet [4.57 m ] for any other public roadway, 10 feet [3.05 m ] or the height of the highest
mobile object that would normally traverse the road, whichever is greater, for a private road, 23 feet [7.01
m ] for a railroad, and 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, would exceed a standard of
subparagraph (1) or (2) of this paragraph.
(4) When requested by the FAA, any construction or alteration that would be in an instrument
approach area (defined in the FAA standards governing instrument approach procedures) and available
information indicates it might exceed a standard of Subpart C of this part.
(5) Any construction or alteration on any of the following airports (including heliports):
(i) An airport that is available for public use and is listed in the Airport Directory of the
current Airman's Information Manual or in either the Alaska or Pacific Airman's Guide and Chart