Proposed US Contribution to ITU-R WP 7A
The abandonment of leap seconds?

nc1985wp7a
Proposed Revised Recommendation ITU-R TF.460-6

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 Hanson. (It has now been removed from the active section of the FCC web site, but it 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 contributions.)

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

• PDF file from Cecily Holiday, chair of the Department of State's ITAC-R National Committee, dated 2005-09-20 indicating that proposed contribution NC1985WP7A is available from the FCC website and subject for review until 2005-10-14T12:00 EDT.
• ITU-R WP7A main page which contains the announcement of the next ITU-R WP7A meeting in Geneva to be held 2005-11-08/11.
• FCC page indicating that Wayne Hanson is the chair of USWP-7A
• NIST contact info page for Wayne Hanson
• Department of State page on ITAC
• Department of State page indicating contact information for Cecily Holiday
• My bibliography of all information available online about the process of abandoning leap seconds
• My plots and Tables showing the long term effect of abandoning leap seconds.
• My history of various time scales and changes in their implementation.

Brief summary of arguments against the proposal

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 failure mode.
• 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 CCTF (a subset of the BIPM , 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.
• Federal Law 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 acceptable.
• 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).