2005 Proposal ITU-R WP 7A from the US
The abandonment of leap seconds?
Proposed Revised Recommendation ITU-R TF.460-6
In 2005 the United States Working Party 7A drafted a new version of the
document which defines UTC with the expectation that it would be
presented to the ITU in November. This document proposed that leap
seconds should be abandoned. The document was subject to public review
until October 14.
The result of the Department of State review was that the US delegation
did not submit this document. However other national delegations
did submit revised versions, and as of 2010 the draft was forwarded
to the ITU-R Radiocommuincations Assembly. It is expected that will
be presented for a vote in 2012, and if 70% of the nations approve
there will be no more leap seconds.
The text of proposals from the US must be publicly circulated
prior to submission to the ITU-R. The document here was obtained
during that review. Once proposals have been submitted to the ITU-R
they are no longer public, so the proposed draft revision as of 2011
is not available.
The MSWord file with a
draft proposed revision to ITU-R TF.460 dated 2005-09-19 from
USWP-7A was available from the
FCC web site.
It contains markup indicating changes made by Ron Beard and Wayne
(It has now been removed from the active section of the FCC web site,
may reappear in the archives.
If any version of it is submitted to the
WP7A of the ITU-R for the 2005 November meeting it will appear as
one of the
The most significant difference between the
2004 proposal (nc1893wp7a)
and the 2005 proposal (nc1985wp7a) is that the date of the change to
the nature of UTC is not to be 2007-12-21, but December 21 of the
year five years after the change is adopted by the ITU-R.
Links to various documents related to the above
Brief summary of arguments against the proposal
Some of the strongest arguments are from
Dr. P.K. Seidelmann, formerly of the US Naval Observatory, editor of
Explanatory Supplement to the Astronomical Almanac,
and member of USWP7A who wrote a
letter indicating that there was no justification for change.
Here is a brief list of some other points
No justification for changing UTC has been presented.
No system which is adversely affected by leap seconds has
been identified along with a believable explanation of its
No serious analysis of the costs of the change (or not making a
change) has been attempted.
The meaning of the term UTC in existing documents (technical and
legal) and existing software will become ambiguous. All references to
UTC will have to be reviewed to ascertain whether the original intent
was to be mean solar time or to be atomic time or simply to be the
conventional civil time scale which happens to be in current use.
The current scheme for UTC will work for 1200 years, the proposed
change fails obviously in 600 years.
Every survey inquiring about a change to UTC produced results which
did not indicate that any change was desired.
Among those most expert in the subject matter at the
2001 meeting of the
(a subset of the
, the keepers of the SI) an informal poll
resulted in a three way tie between change, no change, and apathy.
The time indicated by sundials will no longer bear a fixed
relation to civil time.
The signatories to the
1884 International Meridian Conference agreed
that the civil time everyone should use is based on mean solar time.
indicates that the legal time of the US is based on
mean solar time.
The CGPM (general congress of weights and measures, the international
force behind the SI)
recommendation to use UTC is predicated on the
fact that the leaps keep it reasonably close to mean solar time.
When the proponents convened an
international colloquium in 2003
they were told
not to change UTC (because that would confuse everyone about
its meaning), but to define a new time scale whose purpose was to
serve their needs. They were also told that leap hours were not
The proponents desired to do away with leaps altogether, but as that
would mean that they were using federal funds on labor and travel to
produce a result that was contrary to federal law they re-inserted the
gimmick of a leap hour (to happen in about 600 years).
Steve Allen <firstname.lastname@example.org>
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