Time codes are usually published in the form of UTC, which differs from TAI by a well-known integer number of seconds.

The TAI form may be denoted TAI ( NPL ).

They are published in the form of table of differences from TT ( TAI ).

Since 30 June 2012 when the last leap second was added, TAI has been exactly 35 seconds ahead of UTC.

The SI second was defined in terms of the caesium atom in 1967, and in 1971 it was renamed International Atomic Time ( TAI ).

) TAI was henceforth a realisation of TT, with the equation TT ( TAI )

The continued existence of TAI was questioned in a 2007 letter from the BIPM to the ITU-R which stated " In the case of a redefinition of UTC without leap seconds, the CCTF would consider discussing the possibility of suppressing TAI, as it would remain parallel to the continuous UTC.

International Atomic Time ( TAI ) was set equal to UT2 at 1 January 1958 0: 00: 00.

More precisely, it was defined that TT instant 1977-01-01T00: 00: 32. 184 exactly and TCG instant 1977-01-01T00: 00: 32. 184 exactly correspond to the International Atomic Time ( TAI ) instant 1977-01-01T00: 00: 00. 000 exactly.

Because of the historical difference between TAI and ET when TT was introduced, the TAI realization of TT is defined thus:

TDT is tied in its rate to the SI second, as is International Atomic Time ( TAI ), but because TAI was somewhat arbitrarily defined at its inception in 1958 to be initially equal to a refined version of UT, TT is offset from TAI, by a constant 32. 184 seconds.

where L = 1. 550519768, TDB = − 6. 55 s, T = 2443144. 5003725, and JD is the TCB Julian date ( that is, a quantity which was equal to T on 1977 January 1 00: 00: 00 TAI at the geocenter and which increases by one every 86400 seconds of TCB ).

More precisely, it was defined that TCB instant 1977-01-01T00: 00: 32. 184 exactly corresponds to the TAI instant 1977-01-01T00: 00: 00. 000 exactly, at the geocenter.

More precisely, it was defined that TCG instant 1977-01-01T00: 00: 32. 184 exactly corresponds to TAI instant 1977-01-01T00: 00: 00. 000 exactly.

Air Madagascar was formed in March 1947 by Transports Aériens Intercontinentaux in order to feed into flights by TAI and Air France.

In 1957 TAI and Messageries Maritimes acquired shares in the airline, and in 1958 a third DC-3 was added to the fleet.

On 20 October 1961 a service from Antananarivo-Paris, via Djibouti, with a Douglas DC-7 leased from TAI was inaugurated.

It is the new name for the former TAI – Transporti Aerei Italiani and the former Air Columbia and was operating two Fairchild Metro aircraft from Pescara to Milan and Rome in April 2004 ( replaced by a Dornier 328Jet in January 2005 and a second one in August 2005 ).

The latter is not to be confused with TA ( NPL ), which denotes an independent atomic time scale, not synchronised to TAI or to anything else.

The participating institutions each broadcast, in real time, a frequency signal with time codes, which is their estimate of TAI.

While TT is strictly uniform ( being based on the SI second, every second is the same as every other second ), it is in practice realised by International Atomic Time ( TAI ) with an accuracy of about 1: 10 < small >< sup > 14 </ sup ></ small >.

Its successor time scales, such as TDT, as well as the atomic time scale IAT ( TAI ), were designed with a relationship that " provides continuity with ephemeris time ".

It ticks SI seconds, in step with TAI.

Whereas Unix time is based on Coordinated Universal Time ( UTC ) and is subject to leap seconds, PTP is based on International Atomic Time ( TAI ) and moves forward monotonically.

International Atomic Time ( TAI, from the French name Temps atomique international ) is a high-precision atomic coordinate time standard based on the notional passage of proper time on Earth's geoid.

Time coordinates on the TAI scales are conventionally specified using traditional means of specifying days, carried over from non-uniform time standards based on the rotation of the Earth.

Doing so does not create another version of TAI ; it is instead considered to be creating a better realisation of Terrestrial Time ( TT ).

TT indirectly underlies UTC, via International Atomic Time ( TAI ).

* To millisecond accuracy, TT runs parallel to the atomic timescale ( International Atomic Time, TAI ) maintained by the BIPM.

# January 1, 2000, 11: 59: 27. 816 TAI ( International Atomic Time ).

International Atomic Time ( TAI ) is the primary international time standard from which other time standards, including UTC, are calculated.

Nowadays, UT in relation to International Atomic Time ( TAI ) is determined by Very Long Baseline Interferometry ( VLBI ) observations of distant quasars, a method which has an accuracy of microseconds.

The technique is commonly used for creating and distributing standard time scales such as International Atomic Time ( TAI ).

In the 1970s, it became clear that the clocks participating in TAI were ticking at different rates due to gravitational time dilation, and the combined TAI scale therefore corresponded to an average of the altitudes of the various clocks.

Starting from Julian Date 2443144. 5 ( 1 January 1977 00: 00: 00 ), corrections were applied to the output of all participating clocks, so that TAI would correspond to proper time at mean sea level ( the geoid ).

This is also the instant at which TAI introduced corrections for gravitational time dilation.

TAI is canonically defined retrospectively, in monthly bulletins, in relation to the readings that particular groups of atomic clocks showed at the time.

This is also the instant at which TAI introduced corrections for gravitational time dilation.

This is also the instant at which TAI introduced corrections for gravitational time dilation.

The TAI service, running since 1958, attempts to match the rate of proper time on the geoid, using an ensemble of atomic clocks spread over the surface and low orbital space of the Earth.

TAI as a time scale is a weighted average of the time kept by over 200 atomic clocks in over 50 national laboratories worldwide.

This combined time scale is published monthly in Circular T, and is the canonical TAI.

Errors in publication may be corrected by issuing a revision of the faulty Circular T or by errata in a subsequent Circular T. Aside from this, once published in Circular T the TAI scale is not revised.

In hindsight it is possible to discover errors in TAI, and to make better estimates of the true proper time scale.

This difference may be assumed constant — the rates of TT and TAI are designed to be identical.

MKEK, TAI, Aselsan, Roketsan, FNSS, Nurol, Otokar, and Havelsan are major manufacturers.

TAI builds various aircraft types and models, such as the F-16 Fighting Falcon for the Turkish Air Force.

Other important products include the Altay main battle tank, TF-2000 class AAW frigate, Milgem class corvette, TAI Anka UAV, Aselsan İzci UGV, T-155 Fırtına self-propelled howitzer, J-600T missile, T-129 attack helicopter, Roketsan UMTAS anti-tank missile, Roketsan Cirit laser-guided rocket, Panter Howitzer, ACV-300, Otokar Cobra and Akrep, FNSS Pars 6x6 and 8x8 APC, Nurol Ejder 6x6 APC, TOROS artillery rocket system, Bayraktar Mini UAV, ASELPOD, and SOM cruise missile.

TT is ahead of TAI, and can be approximated as TT ~= TAI + 32. 184 seconds.