Airway Intersections

Right now my nemisis is the FAA and DAFIF data that I use for my waypoint generators. Doing airports and navaids are simple. The problem that’s bugging me right now are the various and sundry “waypoints”, and the ridiculously lax and inconsistent way the FAA and DAFIF files name them.

The problem is that there are thousands of these damn things, and most of them are of no consequence for flight planning. That includes ones that are only of interest to air traffic control themselves, and ones that appear on instrument approaches. Most people don’t enter these points into their flight plan, so they just take up room in your PDA database without being of any use. But while the FAA assigns them waypoint types in their database, the types have almost no bearing on what they really are. I want some way to only select the ones that are airway intersections, but the FAA only uses the type ‘AWY-INTXN’ 8 times in the whole data file. Sometimes they’re ‘REP-PT’, other times they’re ‘WAYPOINT’, other times they’re ‘CNF’ and any number of other designations. But the other waypoints, the ones we don’t care about, also use these same designations with equally gay abandon.

One person suggested that one way to distinguish would be to select only waypoints that have ids that are 5 characters long with no digits. But I’ve just been investigating, and that’s not going to work.

For instance, I’ve been looking at the waypoints in the state of Maine (because the whole state fits on one en-route chart). I selected all the 5 character ids, and then tried to find them on the en-route chart. And the first 10 in alphabetical order turn out to not be intersections – they’re called ‘WAYPOINT’, ‘RNAV-WP’, ‘REP-PT’, and I found a few of them by looking for airports near their latitude/longitude and looking through that airport’s instrument approaches. I found a couple were GPS waypoints.

Oh well, I guess it’s time to look through some of the other FAA data files on the CD to see if there is more information that I can use.

C’est la vie.

4 thoughts on “Airway Intersections”

  1. Here’s a trick for you, Paul. Take a look at the DAFIF file for airways (I think it’s ATS/ATS.TXT, but you’ll have to check), and automatically flag all the intersections that appear in it.

    All the best,


  2. Actually, I’ve found a couple of promising things:

    – The FAA waypoint file lists what charts the waypoint appears on. I could give the option of waypoints that appear on low altitude en-route, high altitude en-route, instrument approachs, and/or none.

    – The DAFIF waypoint file has a “usage code” similar to the above (with “H” for “High altitude”, “L” for “Low altitude”, “B” for “Both”, “R” for “RNAV” and “T” for “Terminal”). The only wrinkle is that “I” and “IF” type fixes are mixed in there.

    I think what I’m going to do is provide check boxes that give you “high”, “low” and “terminal” options, excluding “I” and “IF” DAFIF fixes.

  3. Just tuned into this one… I find myself wondering if you, Kyler Laird, and Paulo Sanchez ever had a conference about all the cool things that you could hack from the FAA databases. You’ve all done lots of great public domain work with them, separately.


  4. Have you guys heard that DAFIF will not be available to the public (even for sale) as of Oct 2005? It’s still up in the air whether or not the U.S. only DAFIF will be available to the public but outside the U.S. won’t be available. I heard this from the DAFIF top dude. Anybody else hear this?

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