Definition and relationship to other standards Weather forecasts, flight plans, air traffic control clearances, and maps all use UTC to avoid confusion about time zones and daylight saving time.Īmateur radio operators often schedule their radio contacts in UTC, because transmissions on some frequencies can be picked up by many timezones. UTC is also the time standard used in aviation. The Network Time Protocol, designed to synchronise the clocks of computers over the internet, encodes times using the UTC system. UTC is the time standard used for many Internet and World Wide Web standards. 2 Definition and relationship to other standards.A number of proposals have been made to replace it with a new system, which would eliminate leap seconds, but no consensus has yet been reached to do so. The system was adjusted several times over the following years, until leap seconds were adopted in 1972 in an effort to simplify future adjustments. The UTC standard was officially standardized in 1961 by the International Radio Consultative Committee, after having been initiated by several national time laboratories. In the 50 years up to and including 2011, a total of 34 leap seconds have been added a 35th leap second is scheduled to be added on 30 June 2012. The only difference between the two is that UTC is occasionally adjusted by adding a leap second in order to keep it within one second of UT1, which is defined by the Earth's rotation. Time zones around the world are expressed as positive or negative offsets from UTC, as in this list.Ĭoordinated Universal Time is based on International Atomic Time (TAI), a time standard calculated using a weighted average of signals from atomic clocks located in nearly 70 national laboratories around the world. For sub-microsecond precision, clients can obtain the time from satellite signals. If only limited precision is needed, clients can obtain the current UTC time from a number of official Internet UTC servers. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose. It is one of several closely related successors to Greenwich Mean Time. The content of this documentation is intended for aviation simulation only and must not be used for real aviation operations.Coordinated Universal Time ( UTC) is the primary time standard by which the world regulates clocks and time.This documentation is copyrighted as part of the intellectual property of the International Virtual Aviation Organisation.VID 150259 - Creation - Wiki integration.

ICAO Documentation Annex 11 - Air Traffic Services - 14th Edition - July 2016 - Chapter 2.26.ICAO Documentation Annex 10 - Aeronautical Telecommunications - Volume II - Communication Procedures - Chapter 3.4.The table below shows an example of offsets used to calculate the standard time in some countries: The difference between UTC time and the standard time is set by national regulation and the difference is given with a multiple of hours and sometimes one half hour is added. Standard time zones around the world are expressed using positive or negative offsets from UTC, as in the list of time zones by UTC offset.

Coordinated universal time utc clock