Updated 10/25/07

Changes to ChartData Due to Removal of DAFIF from the Public Domain


For years, the US Department of Defense (DoD) has collected aviation data from countries all around the world and put it into a massive aviation database that is updated every 28 days.  This database, called DAFIF, is primarily for military use but the DoD also produced a non-classified public version.  Over the years, most aviation software has come to rely on the public DAFIF data to give pilots the official data we need to fly safely.

In November 2004, the DoD announced that, starting October 1, 2005, DAFIF would be completely withdrawn from the public due to intellectual property concerns voiced by a few foreign aviation authorities .  This caused a tremendous outcry from pilots, the aviation industry and AOPA because some of this data, especially airspace information, is not available from any other public source.  In response, the DoD postponed the cutoff date until October 1, 2006 and created a special US-only version of DAFIF, called USFIF, which would be available until October 2007.

Using FAA Data as of October 25, 2007

The FAA is clearly the original source for most US aviation data so it only makes sense, ultimately, that the FAA provide the data directly rather than via the DoD.  They have been working to fill the US digital data gap that the withdrawal of DAFIF produced.  As of this writing, the FAA provides virtually all of the data required for aviation but not quite all of it.  In particular, Seattle Avionics relied on the very detailed airspace data from the DoD to draw airspace.  This data contained a wealth of information beyond simple shapes and altitudes.  For example, it included communication names and frequencies, comments about unusual situations (like some Class D airspace reverting to Class E when the tower is closed) and so forth.  The FAA has chosen to produce most airspace data in a format that many commercial drawing programs can digest called Shapefile.  As the name implies, a shapefile is a file that describes a shape such as an airspace.  Oddly, especially given the name, shapefiles describe all shapes as simple point-to-point line segments.  The DAFIF data, by contrast, was richer in that it described complete shapes as series of line-line segments but also as circles and arcs (think about most Class B, C and D airspace).  While the FAA system of using a large number of points to approximate a circle, rather than just saying something like "5 NM circle at -119.5w / 49n" works, it uses more data space so our data files are larger.  More importantly, the FAA data is lacking a number of crucial bits of inflight information such as contact names and frequencies.  Finally, and most troubling, the FAA shapefile data mentions upper and lower altitudes without reference to whether the altitudes are MSL or AGL.  In most cases, the altitudes are clearly one or the other so our data processing attempts to interpret the altitude correctly but there will be many cases where we won't "guess" correctly. 

We mentioned that the FAA is using shapefiles for most airspace.  They have stated that they will eventually use shapefiles for all airspace, but they currently produce shapefiles for just Class B, C, D and E airspace.  They do not produce shapefiles for Class A or any SUA.  This means that we have no current source of Class A airspace but we do have SUA data because they publish the SUA data in an entirely different format elsewhere.  We process the SUA data from this second source and merge it with the shapefiles for the primary airspace to produce a seamless data set.  This SUA data is much more complete than what we get with the shapefiles; it mentions altitudes as AGL or MSL (usually!), includes contact information, etc.

We have been in contact with the FAA about these problems and they recognize the issues and are working on solutions but have no timeframe.  In the meantime,  please be aware that we are doing the best we possibly can with incomplete data.

Canadian and Mexican Data

Prior to the DAFIF cutoff on October 1, 2006, the Department of Defense provided us with current Canadian and Mexican data.  Since that time, we don't have current data but have provided Canadian and Mexican data that was valid as of that date.  As time continues, this data becomes less and less reliable.  Therefore, we plan to drop the old Canadian and  Mexican data entirely from the standard Voyager data set sometime in 2008.

We clearly recognize the value of this non-US data, not only for Canadian and Mexican pilots, but also for US pilots who fly north or south of the border.  In keeping, we opened communications with Nav Canada.  In 2006, we visited Nav Canada in Ottawa to try to obtain information comparable to what was available from the FAA.  At the time, we learned that, unlike the FAA, which is a government agency with a primary mission to promote aviation safety, Nav Canada is now a privately held company with profit as a main motivation (conceptually similar to the US Post Office).  During the meeting, Nav Canada told us that some data would be available at some point and that we should contact them again in a few months.  Indeed, since that time, they have sent us sample data and we are soon to look at what processing the data entails.  We do not know how much Nav Canada will charge for the data but we have reason to believe it will be in the hundreds of dollars per pilot per year.  When we have reached an agreement with Nav Canada and have worked out the technical details, we'll make an announcement.

We have not made any provisions to get current Mexican data.

What This Means To You

If you are a US pilot who flies only within the 50 states, Puerto Rico, and the US Virgin Islands. you should not notice any major difference, in the long run, but should not be surprised to see some data difference and/or errors for a few data cycles until the FAA fixes the new format.

If you are a Canadian pilot or a US pilot who visits Canada, neither Seattle Avionics nor most other aviation companies can provide you with current data until Nav Canada provides it to us.