VOR Candidate Retention List | Federal Aviation Administration https://www.faa.gov/ato/navigation-programs/vor-retention-li...
> The VOR MON program is designed to enable aircraft, having lost GPS service, to revert to conventional navigation procedures. This will allow users to continue through the outage area using VOR station-to-station navigation or to proceed to a MON airport where an Instrument Landing System (ILS), Localizer (LOC) or VOR approach procedure can be flown without the necessity of GPS, Distance Measuring Equipment (DME), Automatic Direction Finder (ADF), or surveillance. Any airport with a suitable instrument approach may be used for landing, but the VOR MON assures that at least one airport will be within 100 Nautical Miles (NM).
* https://www.faa.gov/about/office_org/headquarters_offices/at...
2011:
* https://www.federalregister.gov/documents/2011/12/15/2011-31...
Is climate change going to make it more difficult to see outside?
Yes, the change we are undergoing and that the current administration seems to be doing their best to accelerate includes an increase in heavy precipitation across north america.