SPECIAL NOTICE: Important Information on Horizontal and Vertical Datums The World Geodetic System 1984 (WGS 84) is used as the horizontal datum for all DOF data. All obstacle data has been converted to WGS 84 as of November 19, 2007. All obstacle data identified with a Julian Date on or after the 71st day of 2001 will be placed in the North American Vertical Datum of 1988 NAVD88. All other elevations in the NACG Digital Obstacle File are in the National Geodetic Vertical Datum of 1929.
A note about data scale:
Scale is an important factor in data usage. Certain scale datasets are not suitable for some project, analysis, or modeling purposes. Please be sure you are using the best available data.
1:24000 scale datasets are recommended for projects that are at the county level. 1:24000 data should NOT be used for high accuracy base mapping such as property parcel boundaries. 1:100000 scale datasets are recommended for projects that are at the multi-county or regional level. 1:125000 scale datasets are recommended for projects that are at the regional or state level or larger.
Vector datasets with no defined scale or accuracy should be considered suspect. Make sure you are familiar with your data before using it for projects or analysis. Every effort has been made to supply the user with data documentation. For additional information, see the References section and the Data Source Contact section of this documentation. For more information regarding scale and accuracy, see our webpage at: <http://geoplan.ufl.edu/education.html>
Distribution Team, Chart Sales Phone: 301-436-8301 Fax: 301-436-6829
Digital Aeronautical Information CD (DAICD) Digital Obstacle File <http://naco.faa.gov/index.asp?xml=naco/catalog/charts/digital/daicd>
DIGITAL OBSTACLE FILE (DOF) READ ME FILE <http://naco.faa.gov/content/naco/catalog/charts/digital/DOF_README.pdf>
SPECIAL NOTICE: Important Information on Horizontal and Vertical Datums As of July 29, 1992 all geographical coordinates in the NACO Digital Obstruction File have been refined and converted to the North American Datum of 1983 (NAD83). The 'Aviation Safety and Capacity Expansion Act of 1990' mandates that all positional data used in the National Airspace System be converted from NAD27 to NAD83. This adjustment is required so that US civil aeronautical charts and databases will be compatible with new navigation systems and equivalent to datums used by the US military and foreign governments. For charting purposes the North American Datum of 1983 (NAD 83) is considered equivalent to World Geodetic System 1984 (WGS 84). The North American Vertical Datum of 1988 (NAVD88) replaces the National Geodetic Vertical Datum of 1929 (NGVD 29) as the official civilian vertical datum for surveying and mapping activities in the United States for all federal agencies. All obstacle data identified with a Julian Date on or after "A1071" (the 71st day of 2001, see explanation of Julian Dates below) will be placed in the North American Vertical Datum of 1988 (NAVD88). All other elevations in the NACO Digital Obstacle File are in the National Geodetic Vertical Datum of 1929.
The original zipfile (DDOF_200803.zip) contained 7 files; BROWSE.EXE, CD_DOF_README.pdf, CD_DOF_README.txt, CHG.DAT, ChkAll_DOF.exe, DAI_DatChk.exe, DOF.DAT
The DOF.DAT file was opened using a text editor. Obstacles within the State of Florida were selected and copied to an Excel spreadsheet.
Next the records were converted from text to columns via the fixed width method. The width format for data in the digital obstacle file was located in the CD_DOF_README.pdf
Next BLANK columns were deleted based on the DOF Format.
Next field names were created based on the DOF Format field information as defined in the CD_DOF_README.pdf
Next the spreadsheet was saved as a .DBF and re-opened in ArcMap.
Next Latitude and Longitude fields were added and populated based on the Geographical Coordinates; Degrees, Minutes, Seconds, found within the table.
Next the table was converted to a shapefile using the Latitude and Longitude fields via the Add XY function in ArcMap.
Next the newly created shapfiles projection was defined as The World Geodetic System 1984 (WGS 84). The projection is based on the source projection information found in the CD_DOF_README.pdf.
Next the shapefile was reprojected from the World Geodetic System 1984 (WGS 84) to the FGDL Albers projection NAD83 HARN.
Finally the following fields were added and populated; USNG_FL_1K DESCRIPT FGDLAQDATE AUTOID