And the people who don't like leap seconds or find them hard to deal with can switch to TAI, which already exists. Need a cheap local source of TAI? Get a GPS. And start setting up an NTP network of TAI timeservers -- anyone doing this yet?

People are doing this. Several manufacturers of NTP servers allow an option where it can *violate the NTP spec* and provide GPS time or TAI instead of UTC. Alternatively, the IEEE 1588 spec for PTP is all about this notion of an operational system time scale based on TAI. Alas, many international agencies responsible for this subject do not have scope of purview to make pronouncements on this subject, and the proceedings of various meetings do not show consensus. During the past decade the pronouncements from the providers of TAI at BIPM have done an about face. In 1999 the CCTF wrote saying yes, use TAI instead of UTC: The CCTF recommends, therefore, that in conformity with this ITU Recommendation developers of future satellite navigation systems and electronic communication systems should link their time scales to TAI as the only alternative to UTC and that, insofar as it is feasible, existing systems take steps to align their time scales with TAI. http://ursiweb.intec.ugent.be/A_97-99.htm But in 2007 the CCTF wrote quite the opposite, saying no, do not use TAI instead of UTC: TAI is the uniform time scale underlying UTC, and that it should not be considered as an alternative time reference. http://www.bipm.org/cc/CCTF/Allowed/18/CCTF_09-27_note_on_UTC-ITU-R.pdf TAI also does not serve POSIX, which specifies that the time_t is based on a trivial relationship to the face-value of UTC and that all days must have 86400 seconds. Unfortunately for POSIX the entire point of the UTC used in radio broadcast time signals since 1972 is that the second is not related to the day. From a system engineering standpoint it makes sense to use TAI, but its providers do not clearly agree. Furthermore, it is not possible to use TAI in an operational system because its value is not available until the next month. Using GPS system time is an available good choice from an engineering standpoint, but GPS does not have international standard status required by some contractual specifications. The previous meeting on the future of UTC re-visited many of these subjects. The final paper at that meeting gave a worked example of using leap-free uniform atomic time (GPS or TAI) for POSIX while still retaining the notion of UTC day defined by earth rotation. Slides and preprints of the 400 pages proceedings are available at http://www.cacr.caltech.edu/futureofutc/2011/index.cfm Steve Allen, UCO/Lick Observatory--ISB, 1156 High Street, Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ +1 831 459 3046 ------------------------------