NavList:

Brad you wrote: "Given your (meaning Dr. Langley's) knowledge of the GNSS system and its susceptibility to solar events, is celestial navigation a prudent backup to GPS navigation if a solar event occurs?" 

Brad

I don’t think you can suggest alternates to cover the extremely remote possibility of World wide temporary failure of all GNSS systems without first looking at the reliability of the suggested alternative itself.  In the case of CN, before even looking at accuracy, we need to look at availability.  For most people operating at the Earth’s surface, the probability of the sky being obscured by cloud (as it is for me right now) must be many orders greater than the possibility of GNSS being unavailable.  Don’t we read in the maritime classics of vessels standing into danger because of the Sun being obscured for days at a time?  The situation was different for aircraft flying above the troposphere where CN was available most of the time and in mid-ocean was of comparative accuracy with existing systems well into the 1980s.  Have an alternative to GNSS by all means, but choose one which will be viable to most users most of the time, not just in choice locations like the Arizona Desert or with star trackers which can work though cloud.  A good question to ask in this particular situation is how might e-Loran be affected by intense solar events?  DaveP