When your custom airport doesn't show in "Nearest Airport"

I recently ran into a problem involving Airport design, specifically, a situation where some of my custom airports were not showing up on a Garmin GPS when using the "Nearest Airport" feature. This was happening with both the PMS50 GTN 750 add-on, and the Garmin 1000 in the stock Asobo Cessna 172. The airport itself is in the sim, and you can spawn a flight at any of the parking spaces or runway starts, and you could type in the ICAO in the Garmin in "Direct To" mode, and plot a flight path to the airport, but the "Nearest Airport" feature wouldn't show it. The airports in question are CYCY (Clyde River), CYAB (Arctic Bay), CYSY (Sach's Harbour), and CYVL (Colville Lake), all in Cahada's NWT or Nunuvut. There are at least 25 airstrips in NWT and Nunavut that have been built or improved in recent years by the NWT and Nunavut Provincial governments, but as of 2026, Asobo has still not included them in the FS2020 stock scenery. These are all un-towered dirt and gravel strips, but some of them actually have PAPI2 or PAPI4 approach lights - you can see them on Google Earth images - and all of them have small terminal buildings, and at least occasional service from small regional airlines.

So I have begun a project to make airports at all 25 of these neglected places in Canada's far north, and had completed nine of them, when I made the disturbing discovery that four of them are invisible to the "Nearest Airport" feature, even when the plane is right there at the airport in question. So, I began digging through my XML source files, trying to find some errors that might account for why those four airports were having this problem, when the other 5 were okay. And after a full week of head scratching and frustration, I finally found the problem, and it's not something most people would ever think of: it was runway material. The five airports that didn't have the problem all had runways coded with either Asphalt or the Asobo "Gravel01" material. The four malfunctioning airports all had the runway coded with "Gravel_Ground", also from the Asobo library, so it's a stock material in the SDK. The GUID for this material is [05C575AB-4367-42AA-963F-F0F1EACBC400].

I have just re-coded all runways, ground polygons, and aprons, to use Gravel_01, surface GUID [9E7A4A2E-32C0-4495-BDDF-79B24AFB25ED], and now the four airports show up in the GPS "Nearest Airport" function as you would expect. I can't explain why the sim's internal functioning would have an issue with a material that is in the official Asobo library; maybe the software that searches the scenery database for airports when you click the "Nearest Airport" button on a GPS, cross references a list of runway materials, and this list either doesn't include Gravel_Ground, or there's just a glitch in the software somewhere that's never been noticed until now.