(b) The notice required under 77.13 (a) (1) through (4) must be submitted at least 30 days before the
earlier of the following dates -
(1) The date the proposed construction or alteration is to begin.
(2) The date an application for a construction permit is to be filed.
However, a notice relating to proposed construction or alteration that is subject to the licensing
requirements of the Federal Communications Act may be sent to the FAA at the same time the application
for construction is filed with the Federal Communications Commission, or at any time before that filing.
(c) A proposed structure or an alteration to an existing structure that exceeds 2,000 feet [609.60 m] in
height above the ground will be presumed to be a hazard to air navigation and to result in an inefficient
utilization of airspace and the applicant has the burden of overcoming that presumption. Each notice
submitted under the pertinent provisions of Part 77 proposing a structure in excess of 2,000 feet [609.60 m]
aboveground, or an alteration that will make an existing structure exceed that height, must contain a
detailed showing, directed to meeting this burden. Only in exceptional cases, where the FAA concludes
that a clear and compelling showing has been made that it would not result in an inefficient utilization of
the airspace and would not result in a hazard to air navigation, will a determination of no hazard be issued.
(d) In the case of an emergency involving essential public services, public health, or public safety,
that requires immediate construction or alteration, the 30-day requirement in paragraph (b) of this section
does not apply and the notice may be sent by telephone, telegraph, or other expeditious means, with an
executed FAA Form 7460-1 submitted within five days thereafter. Outside normal business hours,
emergency notices by telephone or telegraph may be submitted to the nearest FAA Flight Service Station.
(e) Each person who is required to notify the Administrator by paragraph (b) or (c) of 77.13, or both,
shall send an executed copy of FAA Form 117-1, Notice of Progress of Construction or Alteration, to the
Chief, Air Traffic Division, FAA Regional Office having jurisdiction over the area involved.
77.23 Standards for determining obstructions.
(a) An existing object, including a mobile object, is, and a future object would be, an obstruction to
air navigation if it is of greater height than any of the following heights or surfaces:
(1) A height of 500 feet [152.40 m] above ground level at the site of the object.
(2) A height that is 200 feet [60.96 m] above ground level or above the established airfield
elevation, whichever is higher, within 3 nautical miles [5 559.55 m] of the established reference point of an
airport, excluding heliports, with its longest runway more than 3,200 feet [975.36 m] in actual length and
that height increases in the proportion of 100 feet [30.48 m ] for each additional nautical mile [1852.00 m]
of distance from the airport up to a maximum of 500 feet [152.4 m].
(3) A height within a terminal obstacle clearance area, including an initial approach segment, a
departure area, and a circling approach area, which would result in the vertical distance between any point
on the object and an established minimum instrument flight altitude within that area or segment to be less
than the required obstacle clearance.