Temporal Reference System
The Gregorian calendar and Coordinated Universal Time (UTC) shall be used as the temporal reference system for air navigation.
Daylight saving time is UTC plus 1 hour. The expression “summer period” indicates that part of the year in which “daylight saving time” is in force. The other part of the year is named the “winter period”. Times applicable during the “summer period” are given in brackets.
The “summer period” is introduced every year on the last Sunday in MAR at 01:00 UTC and ceases on the last Sunday in OCT at 01:00 UTC.
Examples of time periods expressed in AIS Products
Every day, without change during summer period
0500-2100
Explanation: The same time in UTC during the whole year regardless of winter or summer periods.
On the days notified, without change during summer period
Mon, Wed, Fri 0500-2100
Explanation: The period covers every Monday, Wednesday and Friday same time in UTC during the whole year regardless of winter or summer periods.
Every Day during the Winter Period only
0500-2100 winter only
Explanation: The same time in UTC during the winter period only.
Every Day during the Summer Period only
(0500-2100) summer only
Explanation: The same time in UTC during the summer period only.
Every day in winter, every day in summer
0500-2100 (0415-2130)
Explanation: Period covers from 05:00UTC until 21:00UTC during winter period and from 04:15UTC until 21:30UTC during summer period.
0500-2359 (H24)
Explanation: Period covers every day from 05:00UTC until 23:59UTC during winter period, and every day H24 during summer period.
Every day in winter, every day in summer, with additional reference to SS
0900-2000 (0800-1900); or SS+15, whichever is earlier.
Explanation: Period covers every day from 09:00UTC until 20:00UTC or sunset +15 minutes, whichever is earlier, during winter period; and every day from 08:00UTC until 19:00UTC or sunset +15 minutes, whichever is earlier, during summer period.
During the same day throughout the year
Mon 0700-2300 (0600-2200)
Explanation: Period covers EVERY Monday from 07:00UTC until 23:00UTC during winter period and EVERY Monday from 06:00UTC until 22:00UTC during summer period.
During the week
Mon-Fri 0700-2300 (0600-2200)
Explanation: Period covers EVERY Monday to Friday from 07:00UTC until 23:00UTC during winter period and EVERY Monday to Friday from 06:00UTC until 22:00UTC during summer period.
During the whole weekend
Sat, Sun 0700-2300 (0600-2200)
Explanation: Period covers EVERY Saturday and Sunday from 07:00UTC until 23:00UTC during winter period and EVERY Saturday and Sunday from 06:00UTC until 22:00UTC during summer period.
During the whole week
Mon 0700 (0600) - Fri 2300 (2200)
Explanation: Period covers from Monday 07:00UTC until Friday 23:00UTC during winter period and from Monday 06:00UTC until Friday 22:00UTC during summer period.
Every day same time winter, specific days and times in summer, excluding public holidays
0500-2330 (Mon-Fri 0430–0100; Sat 0500–0100); excluding PH.
Explanation: Period covers from 05:00UTC until 23:30UTC during winter period and EVERY Monday to Friday from 04:30UTC until 01:00UTC on the following day during summer period, and EVERY Saturday from 05:00UTC until 01:00UTC on the following day during summer period; excluding public holidays.
During the same day winter, every day in summer
Mon 0700-2200 (Mon-Sun 0600-2200)
Explanation: Period covers every Monday 07:00UTC until 22:00UTC during winter period and every day from 06:00UTC until 22:00UTC during summer period.
Overnight during the year, between specified days
Mon-Wed 23:00-05:00 (22:00-04:00)
Explanation: Period covers EVERY NIGHT from Monday 23:00UTC until Tuesday 05:00UTC, from Tuesday 23:00UTC until Wednesday 05:00UTC and from Wednesday 23:00UTC until Thursday 05:00UTC during winter period and EVERY NIGHT from Monday 22:00UTC until Tuesday 04:00UTC, from Tuesday 22:00UTC until Wednesday 04:00UTC and from Wednesday 22:00UTC until Thursday 04:00UTC during summer period.