NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Leap seconds a navigational hazard, says expert
From: Paul Hirose
Date: 2003 Aug 8, 12:10 -0700
From: Paul Hirose
Date: 2003 Aug 8, 12:10 -0700
The Guardian has an article about the debate in the technical community on leap seconds. Some are worried the divergence of UTC with respect to other time scales will cause a crash some day, figuratively if not literally. "Widening gaps between GPS time used by aircraft navigation systems and the time used on the ground could generate confusion between a plane's report and actual position, he says, and so increase the risk of collision. A complicated situation will get more complex when Europe launches its own GPS system, Galileo, which will be based on yet another version of time. "Computer software converts between the different timescales used. 'But if anybody ever makes a mistake there's going to be a big problem,' Mr Klepczynski says. His solution is to scrap the leap second, effectively merging atomic time and universal time. This is also the proposal being considered by the time lords of the ITU." http://www.guardian.co.uk/uk_news/story/0,3604,985020,00.html If that becomes reality, celestial navigators will eventually have to begin applying the UT1 - UTC correction. Currently the leap seconds keep that difference below 1 second. The value in tenth seconds is transmitted by radio time stations using a pattern of double ticks after the beginning of each minute. However, the code has no provision for offsets of 1 second and more. Right now Earth is about .35 seconds behind UTC. A year from now it should be about .42 second behind, according to IERS Bulletin A. http://maia.usno.navy.mil/ http://tycho.usno.navy.mil/leapsec.html (Windows users - some documents on these pages may not display properly with Notepad. Use Wordpad to view them.)