Paul, wow, thank you!! It's going to take me some time to dissect and absorb how you did it, but I think I get the basic gist. Loop through the airports database and for each airport, pass in the airport to the FsAirport.COMFreqencies property to get all the frequencies at that airport, loop through those frequencies and add them to the datagrid, then move on to the next airport.
I did see the FsAirport.COMFrequencies property, and knew I could get all the frequencies for an airport, just wasn't sure if/how I bring the two together. I'm glad there is a way!
Ultimately, I'd like to turn this into a real-time update, say every 5 seconds or so, so the app is continually displaying all available frequencies within a specified distance from the player. Would it make more sense performance-wise to build the list just once, store it in memory (an array, maybe?), then call that versus rebuild the grid every time?
Again, thank you!