Another article with some more details: https://www.pcmag.com/news/the-faa-is-still-using-floppy-dis...
I know they are saying IDS-4 is a "1980s" system, but it appears IDS-4 was actually developed in the early 1990s; it uses MS-DOS and 3.5 inch floppies: https://sysatl.com/systems-atlanta-inc-awarded-faa-ids4-sust...