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United States Department of TransportationUnited States Department of Transportation

Digital Obstacle File (DOF) - Frequently Asked Questions

Is the DOF data considered to be in the public domain? Are there any restrictions on using the DOF data?
Yes, it is in the public domain. There are no restrictions on how you may use the data, but you are not allowed to change the data.

In the DOF, how does one differentiate between a dismantled structure and an existing structure at the same location?
In our Digital Obstacle File (DOF), the letter in the "Verified Status" column shows whether a structure is Unverified (U) or Verified (V). The letter in the "Action" column shows the last action performed on the file, which can be Added (A), Changed (C), or Dismantled (D).

Why does the City Name field sometimes show "CITY, STATE" instead of the normal "CITY"?
The obstacle may be in one state, but the nearest associated city might be across the border in another state. The DOF was originally created for internal use by our Visual Charting team, and the nearest associated city/state name helps them locate the area on the chart to plot the obstacle. It also gives our users a quick reference as to its location.
Users should be aware that the DOF contains more than 6,000 records with a comma ("CITY, STATE") in the City Name field. Using this format has been a part of our standard operating procedures since the 1970's.

In your database, is there a field that specifies whether obstructions are single or group?
Yes. Currently, the "OBSTACLE TYPE" column includes the number of structures in that file, to the right of the actual structure type.

Do you have shape files for your DOF data?
None of our products include shape files for DOF data.

Do you have more specific metadata for your obstacles? (i.e. Is a "sign" a traffic sign, a billboard, etc?)
We do not differentiate the various obstacle types. What you see in the DOF is as specific as we get.

Do you have more specific metadata for your "TREE" and "VEGETATION" obstacles?
We only differentiate between trees and other vegetation.

Your database does not seem to contain many buildings that exist in a particular area. Does the DOF not include all tall structures?
This office is tasked to maintain data on all structures over 200 feet above ground level and lower structures affecting F.A.R. Part 77 in the vicinity of airports with approach procedures. Maintaining an accurate, updated database depends entirely upon structures being reported to us in timely fashion by several sources, mainly the FAA's OE/AAA group, but also NOAA, FCC, NGA and other federal agencies. When tall structures are built and not reported to this office, this could have a negative effect on air navigation and would be of concern to us.
If you have not found certain existing structures in the online DOF, you should go to the following, and check the various search options on the left side of the page: Obstruction Evaluation / Airport Airspace Analysis (OE/AAA)
Note, many of the structures listed with the OE/AAA are in proposal or construction stage, and thus would not be listed in the DOF. However, there may be time lag between completion of a project and reporting to this office. Please do inform us of any structures that have been constructed and that you believe are over 200 feet above ground level height that are not listed in the DOF. You would need to provide us with an exact location with coordinates (GPS, Google Earth, other documentation) and any other information you might have (exact or approximate heights, current owner, etc.). We will have our analysts investigate to make sure all structures affecting navigable airspace are properly accounted for.

Does the DOF contain obstacles for approach procedures (found on the FAA form 8260)? If so, is there attribution that identifies which procedure the obstacle belongs to? If not, is there a publicly available data file that contains all of the 8260 obstacles?
The obstacles (manmade) for approach procedures are in the DOF database, but the attribution for the procedure is not part of the existing file. You would have to do a DOF search of the airport coordinates to obtain the listing of potential obstacles.

Where/what is the DVOF?
DVOF (Digital Vertical Obstruction File) is a Dept of Defense/NGA product not distributed through the FAA Obstacle Data Team website. Please visit the National Geospatial-Intelligence Agency.

If you have a question that you do not see here, please see Aeronautical Inquiries.

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