47 CFR § 17.7 - Antenna structures requiring notification to the FAA.
A notification to the FAA is required, except as set forth in paragraph (e) of this section, for any of the following construction or alteration:
(a) Any construction or alteration of more than 60.96 meters (200 feet) in height above ground level at its site.
(b) Any construction or alteration that exceeds an imaginary surface extending outward and upward at any of the following slopes:
(1) 100 to 1 for a horizontal distance of 6.10 kilometers (20,000 feet) from the nearest point of the nearest runway of each airport described in paragraph (d) of this section with its longest runway more than 0.98 kilometers (3,200 feet) in actual length, excluding heliports.
(2) 50 to 1 for a horizontal distance of 3.05 kilometers (10,000 feet) from the nearest point of the nearest runway of each airport described in paragraph (d) of this section with its longest runway no more than 0.98 kilometers (3,200 feet) in actual length, excluding heliports.
(3) 25 to 1 for a horizontal distance of 1.52 kilometers (5,000 feet) from the nearest point of the nearest landing and takeoff area of each heliport described in paragraph (d) of this section.
(c) 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 an obstruction standard of the FAA.
(d) Any construction or alteration on any of the following airports and heliports:
(1) A public use airport listed in the Airport/Facility Directory, Alaska Supplement, or Pacific Chart Supplement of the U.S. Government Flight Information Publications;
(2) A military airport under construction, or an airport under construction that will be available for public use;
(3) An airport operated by a Federal agency or the United States Department of Defense.
(4) An airport or heliport with at least one FAA-approved instrument approach procedure.
(e) A notification to the FAA is not required for any of the following construction or alteration:
(1) Any object that will be shielded by existing structures of a permanent and substantial nature or by natural terrain or topographic features of equal or greater height, and will be located in the congested area of a city, town, or settlement where the shielded structure will not adversely affect safety in air navigation;
(2) Any air navigation facility, airport visual approach or landing aid, aircraft arresting device, or meteorological device meeting FAA-approved siting criteria or an appropriate military service siting criteria on military airports, the location and height of which are fixed by its functional purpose;
(3) Any antenna structure of 6.10 meters (20 feet) or less in height, except one that would increase the height of another antenna structure.
Consideration to aeronautical facilities not in existence at the time of the filing of the application for radio facilities will be given only when proposed airport construction or improvement plans are on file with the Federal Aviation Administration as of the filing date of the application for such radio facilities.