What is UTC (Coordinated Universal Time) or ZULU time

What is UTC (Coordinated Universal Time) or ZULU time, in other words; Do you know?

The UTC time system is particularly important in aviation.

UTC or ZULU (Z) system is used in many critical documents such as weather reports (METAR, TAF…) and flight plans published for daily operations.

In this way, conflicts that may arise from time zone differences are prevented. Workload on air traffic management is reduced. The workload on the pilots is reduced and a common time planning is made possible.

Let’s think of a situation like this, consider a plane departing from Vancouver / Canada and going to Berlin / Germany. During such a flight, the plane will cross the airspaces in many different time zones. Imagine that the plane entering each different time zone flies according to the local time value of that region? Imagine that each air traffic controller communicates with that unit’s local time values? Such a situation will bring a huge workload. Or, for example, imagine that a NOTAM (notice to airman) for an international airport is broadcast with the local time values. How difficult a situation arises for the aircraft that will fly to that airport, right?

zulu time

For these and many other reasons, a common use of a standart time value in aviation is required. Well let’s examine the UTC / ZULU time a little more.

UTC was first introduced in 1960. UTC is an acronym for the French word Temps universel coordonné and English Coordinated Universal Time. Since there is no consensus on the French (TUC) and English (CUT) abbreviations, UTC was decided, unlike both. Since UTC is calculated atomically, there are slight differences from GMT calculated for solar time, but they do not affect everyday use.

In UTC format Midnight shall be designated as 2400 for the end of the day and 0000 for the beginning of the day.

World Time zone

In the table below, you can find some countries’ calculations for UTC time zones. For example: 1530 UTC time is equal to UTC + 1 in paris, ie 1630 Local time.

London (UK)UTC+0Wellington(New Zealand)UTC+12
Paris (France)UTC+1Nuku’olofa(Tonga)UTC+13
Ankara(Turkey)UTC+2Pago Pago(Samoa)UTC-11
Manama(Bahrain)UTC+3Tahiti(French Polynesia)UTC-10
Teheran(Iran)UTC+3:30Anchorage(USA)UTC-9
Moscow(Russia)UTC+4San Francisco(USA)UTC-8
Karachi(Pakistan)UTC+5El Paso(USA)UTC-7
Delhi(India)UTC+5:30Chicago(USA)UTC-6
Yekaterinburg(Russia)UTC+6New York(USA)UTC-5
Phnom Penh(Cambodia)UTC+7Caracas(Venezuela)UTC-4
Canton(China)UTC+8Halifax(Canada)UTC-4
Tokyo(Japan)UTC+9Rio de Janeiro(Brazil)UTC-3
Canberra(Australia)UTC+10Fernando de Noronha(Brazil)UTC-2
Nouméa(New Caledonia)UTC+11  

Table source: INTERNATIONAL VIRTUAL AVIATION ORGANIZATION

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