Sec. 21.116  Topographical data.

    Determining the location and height above sea level of the antenna 
site, the elevation or contour intervals shall be taken from United 
States Geological Survey Topographic Quadrangle Maps, United States Army 
Corps of Engineers maps or Tennessee Valley Authority maps, whichever is 
the latest, for all areas for which such maps are available. If such 
maps are not published for the area in question, the next best 
topographic information should be used. Topographic data may sometimes 
be obtained from State and municipal agencies. Data from Sectional 
Aeronautical Charts (including bench marks) or railroad depot elevations 
and highway elevations from road maps may be used where no better 
information is available. In cases where limited topographic data is 
available, use may be made of an altimeter in a car driven along roads 
extending generally radially from the transmitter site. If it appears 
necessary, additional data may be requested. United States Geological 
Survey Topographic Quadrangle Maps may be obtained from the Department 
of the Interior, Geological Survey, Washington, DC 20242. Sectional 
Aeronautical Charts are available from the Department of Commerce, Coast 
and Geodetic Survey, Washington, DC .
[44 20230 FR 60534 , Oct. 19, 1979, as amended at  52 FR 37783 , Oct. 9, 1987]