Navigation Editing: How you get your ILSes, Fixes, VORs and NDBs

Hi All,

Today I thought I’d give a bit of insight into how a group of the airport editing team edit ILSes, Fixes, VORs and NDBs. I’ll just be showing you how we do ILSes for now because the others aren’t very interesting, but here it is.

The ILS I’ll be editing today is Runway 04 at Kristansand Kjevik (ENCN). I start by finding the part of the glideslope and localiser files that take care of this approach. This is what they look like:

For those who don’t understand this, try looking at it this way:

Glideslope (Left)

Reception Range 10
Bearing 35.898
Elevation 57
Name GS

And so on…

It’s basically a database, where the data is in orange or green on the right of each side and what that data is is on the left of each side in blue.

I work my way from top to bottom, so starting with the bearing. To find this, I go into WED, the program we airport editors use to, er, edit airports and import the file for the airport with the ILS I’m editing. In this case, ENCN. When finished, it looks like this:

To get the bearing, I find the runway in the list of objects and bring up it’s information. Here’s the result:

It’s a lot, but I only need one part of it; the heading. Since I’m editing runway 03 I can just grab the heading straight from the tab, which is 34.96. That’s what I put into the glideslope and localiser files. They then look like this (blue bars indicate changes on those lines).

Next, I skip the ICAO (because I’m counting on that being correct!) and head to the elevation. This is displayed in feet. I go back into WED and select the airport, which brings up this information.

The elevation is plain to see, so I would normally input that into both files as well but in this case it’s already correct.

The name I leave as-is. Then I need to grab the latitude and longitude for the runway. This can’t be done in WED, so I need to open up the raw airport file, which looks like this.

(There is more)
I won’t show you how I get the coordinates but they’re on line 5, see if you can spot it for runway 03.

Anyway, once they’re inputted the glideslope and loc files look like this:

Next I look at the associated runway number. As the runway number was changed when the airport was last reworked, I need to update the number in the glideslope and loc files like so:

Now I need to pull up the charts, here’s the ones I’m using:

As indicated at the bottom of the page, the glidepath (GP) is 3.4 degrees. But if I put this into the glideslope field it won’t work. The format for this field is Glidepath angle then heading without the decimal place. So as the GP is 3.40 and the heading is 34.960 what I put in is 3.4034960.

Last but not least I need to check the ILS frequency is correct in accordance with the charts. It’s not, so I change it.

And that’s it! This is how you get your ILS approaches. Every ILS approach in IF is in both these files (the glideslope file is 1.03MB and the LOC one is 1.9MB). Expect this approach to be added in the next scenery update.

Should I show you how we add VORs, NDBs and Fixes?

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Wow! This is very interesting! Interesting on how people make ILS approaches.


Thank you for the insight! I never thought that there is so much work behind a „simple“ ILS.

The IFAET is doing a fantastic job. You put a lot of work into this, you deserve much more appreciation. We always fly at those airports, we use the ILS, we see VORs but for us they’re just there. It’s easy to forget that a lot of what we see has been added manually by some of you guys. That’s remarkable.

Thank you, and yes; I’d be interested to read more!


Thanks for the kind words. I’m currently working on the other end of ENCN’s runway before I make a PR so it can be merged into the Nav repo.


That’s a great insight, thanks for sharing! Never thought it was that complicated!

Really looking forward to learn something about fixes, VORs and NDBs next!

I know how to code… so yes, I understand.