Archived posting to the Leica Users Group, 2007/02/25
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At 10:50 AM 2/25/2007, Lawrence Zeitlin wrote: >As far as knocking out GPS by hostile intent, it can only be done >over a very limited area, i.e. over a city or a harbor. Usually the >area is smaller than the accuracy limits of celestial navigation. >Furthermore, alternative electronic navigation methods (e.g. LORAN) >are even more useful than GPS in coastal areas. I'm glad the Air >Force and Navy stopped training navigators in celestial navigation >methods. Technology has demystified another arcane skill and saved us >taxpayers a bundle of money. Larry The Chinese are building rockets to knock out the GPS satellites. They tested one about a month ago, successfully. No satellites, no GPS. And the Air Force still requires celestial navigation for aircrew -- and they do have precision chronometers and updated almanacs on their aircraft. It would be more than a bit embarrassing if the Chinese took out the GPS grid and our bombers on the way to clobber the PRC had to stop to ask directions. For that matter, it's only been in the past twenty years that commercial aircrew in international flights no longer needed to know celestial navigation: I had a client at that time who was one of the last to have had to pass an exam on it to get his ATR endorsed for international flights. Marc msmall@aya.yale.edu Cha robh b?s fir gun ghr?s fir!