Australia uses Coordinated Universal Time (UTC) for all civil aviation operations (AIP GEN 2.1).
The term ‘Zulu’ is used when ATC procedures require a reference to UTC, for example:
0920 UTC is said as ‘zero nine two zero zulu’
0115 UTC is said as ‘zero one one fife zulu’
Converting from Standard Time to UTC
Eastern Standard Time
Subtract 10 hours
Central Standard Time
Subtract 9.5 hours
Western Standard Time
Subtract 8 hours
Note Daylight saving is not applied universally across Australia and is not published in the AIP. See AIP SUP and NOTAM Daylight Saving.
The 24-hour clock system is used in radiotelephone transmissions. The hour is indicated by the first two figures and the minutes by the last two figures. For example:
0001 is said as ‘zero zero zero one’
1920 is said as ’one nine two zero’
Time may be stated in minutes only (two figures) in radiotelephone communications when no misunderstanding is likely to occur. Current time in use at a station is stated to the nearest minute in order that pilots may use this information for time checks.
Control towers will state time to the nearest half minute when issuing a taxi clearance to a departing aircraft. For example:
0925:10 is said as ‘time, two five’
0932:20 is said as ‘time, three two and a half’
2145:50 is said as ‘time, four six’
Date and time are indicated in a combination of the date and time in a single six- figure group. However, a 10-figure group comprising the year, month, date, hours and minutes is used for NOTAMs and SUPs. This is reduced to an eight-figure group (nil year) for a specific pre-flight information bulletin (SPFIB). The format is yymmddhhmm. For example:
1215 hours UTC on 23 March 2010 would be written as 1003231215