[roenxi]

If something unforeseen happens an the GNSS systems go down for whatever reason we might be set up for a terrifying few months of disruption. Coronavirus was bad enough, and most of the disruptions were voluntary to some extent.

[scoopertrooper]

If all the various GNSS constellations went down simultaneously we'd definitely be in the shit. Not just because we lost GNSS, but we'd also probably be fighting a war or Kessler syndrome would be in effect. Either way, losing GNSS would be just one of many problems!

[p_l]

We still have VOR network and other legacy systems. Some are no longer integrated into parts of the avionics but you can still plan routes and use them to fly. Plus Primary Surveillance Radar will see you anyway.

[bronco21016]

I wonder how long it will take to get the VOR network serviceable. Many of them are no longer maintained.

[p_l]

some dropped off maintenance, but not all. NDB is pretty much dead outside of few rare spots, though, and not everywhere had DME even at best time. But nav points used with GPS still often are based on VOR locations.