[Code of Federal Regulations]
[Title 14, Volume 2]
[Revised as of January 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 14CFR77.23]

[Page 160-161]
 
                     TITLE 14--AERONAUTICSAND SPACE
 
CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION 
                               (CONTINUED)
 
PART 77--OBJECTS AFFECTING NAVIGABLE AIRSPACE--Table of Contents
 
                    Subpart C--Obstruction Standards
 
Sec. 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 above ground level at the site of the 
object.
    (2) A height that is 200 feet above ground level or above the 
established airport elevation, whichever is higher, within 3 nautical 
miles of the established reference point of an airport, excluding 
heliports, with its longest runway more than 3,200 feet in actual 
length, and that height increases in the proportion of 100 feet for each 
additional nautical mile of distance from the airport up to a maximum of 
500 feet.
    (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.
    (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 Sec. 77.25, Sec. 77.28, or 
Sec. 77.29. However, no part of the take-off or landing area itself will 
be considered an obstruction.

[[Page 161]]

    (b) Except for traverse ways on or near an airport with an operative 
ground traffic control service, furnished by an air 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) Seventeen 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) Fifteen feet for any other public roadway.
    (3) Ten feet or the height of the highest mobile object that would 
normally traverse the road, whichever is greater, for a private road.
    (4) Twenty-three feet for a railroad, and,
    (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.

[Doc. No. 10183, 36 FR 5970, Apr. 1, 1971]