Living in an APNT World
It’s all about the backups now. The alternatives. The gap-fillers.
Back in the 1990s, when I first came across the U.S. Federal Radionavigation Plan (FRP), I learned that the rise of the Global Positioning System drove the biannual FRP process because of the expectation that GPS would enable the government to shut down many pieces in the hodgepodge of positioning, navigation, and timing (PNT) systems.
By Inside GNSS