Sec. 101.127  Topographical data.

    Determining the location and height above sea level of the antenna 
site, the elevation or contour intervals must 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

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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 
20230.