Nearly every day I hear from at least one person who thinks I am an idiot. Typically they are complaining about something I wrote months or even years before, so I often confirm my idiocy by not even remembering what has them so upset. This week, however, I was contacted by an upset reader who may well have a good point, so let’s reconsider for a moment the security of Global Positioning System — GPS.

I wrote more than a year ago that a Government Accountability Office report was overblown, claiming a 20 percent chance of the GPS system going down in the next few years because the U. S. Air Force can’t launch […]