§  73.312   Topographic data.

   (a) In the preparation of the profile graphs previously described, and
   in determining the location and height above mean 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. The data from
   the 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 can be obtained, use may be made of an altimeter in a
   car driven along roads extending generally radially from the
   transmitter site.

   (b) The Commission will not ordinarily require the submission of
   topographical maps for areas beyond 24 km (15 miles) from the antenna
   site, but the maps must include the principal city or cities to be
   served. If it appears necessary, additional data may be requested.

   (c) The U.S. Geological Survey Topography Quadrangle Sheets may be
   obtained from the U.S. Geological Survey Department of the Interior,
   Washington, DC 20240. The Sectional Aeronautical Charts are available
   from the U.S. Coast and Geodetic Survey, Department of Commerce,
   Washington, DC 20235. These maps may also be secured from branch
   offices and from authorized agents or dealers in most principal cities.

   (d) In lieu of maps, the average terrain elevation may be computer
   generated except in cases of dispute, using elevations from a 30
   second, point or better topographic data file. The file must be
   identified and the data processed for intermediate points along each
   radial using linear interpolation techniques. The height above mean sea
   level of the antenna site must be obtained manually using appropriate
   topographic maps.

   [ 28 FR 13623 , Dec. 14, 1963, as amended at  31 FR 10126 , July 27, 1966;
    49 FR 48937 , Dec. 17, 1984;  58 FR 44950 , Aug. 25, 1993;  63 FR 33877 ,
   June 22, 1998]