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

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www.fer3.com/arc