§  80.757   Topographical data.

   (a) In the preparation of profile graphs and in determining the
   location and height above sea level of the antenna site, the elevations
   or contour intervals must be taken from U.S. Geological Survey
   topographic quadrangle maps, U.S. Army Corps of Engineers maps or
   Tennessee Valley Authority maps, whichever is the latest, for all areas
   for which maps are available. If such maps are not published for the
   area in question, the next best topographic information must be used.
   The maps used must include the principal area to be served. U.S.
   Geological Survey topographic quadrangle maps may be obtained from the
   Eastern Distribution Branch, U.S. Geological Survey, 1200 South Eads
   Street, Arlington, VA 22202, for maps of areas east of the Mississippi
   River, including Minnesota, Puerto Rico, and the Virgin Islands, and
   from the Western Distribution Branch, U.S. Geological Survey, Federal
   Center, Denver CO 80225, for maps of areas west of the Mississippi
   River, including Alaska, Hawaii, Louisiana, Guam and American Samoa.
   Sectional aeronautical charts are available from the Distribution
   Division, National Ocean Service, Riverdale, MD 20840.

   (b) In lieu of maps, the average terrain elevation may be computer
   generated, using elevations from a 30 second point or better
   topographic data file such as those available for the U.S. Geological
   Survey's National Geographic Information Center or the National Oceanic
   and Atmospheric Administration's National Geophysical Data Center. In
   case of dispute maps will be used to determine the correct value.