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E6B Calc

Zulu Time Does Not Change for Daylight Saving

No, Zulu time never changes for daylight saving, anywhere, ever. Zulu is UTC, and UTC has no seasons. What changes is the offset your local clock uses to read it, and that offset moves on a different date in the US, in Europe and in Australia.

4 min read · Updated 2026-09-11

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UTC is the clock, local time is the label

Think of Zulu as the one clock nobody touches. Every local zone is a sticky note on top of it, saying "subtract 5 here" or "add 2 there," and daylight saving only rewrites the note. 1400Z is 1400Z in January and in July.

That is why flight plans, NOTAMs and METARs use it: a crew in Denver and a controller in London read the same instant without a time-zone lookup.

Worked conversions across a real 2026 clock change

The offsets below come from each zone's actual 2026 transition date, computed with Python's zoneinfo (America/New_York, Europe/London, Europe/Madrid, Australia/Sydney), not from memory. The US moves clocks forward on 8 March 2026; the EU (London and Madrid) follows three weeks later, on 29 March 2026. 1400Z stays 1400Z through both; only the local column moves.

1400Z shown as local time, before and after each 2026 clock change
1400Z onNew YorkLondonMadridSydney
7 Mar 2026 (before US change)09:00 EST14:00 GMT15:00 CET01:00 (+1 day) AEDT
9 Mar 2026 (after US change)10:00 EDT14:00 GMT15:00 CET01:00 (+1 day) AEDT
28 Mar 2026 (before EU change)10:00 EDT14:00 GMT15:00 CET01:00 (+1 day) AEDT
30 Mar 2026 (after EU change)10:00 EDT15:00 BST16:00 CEST01:00 (+1 day) AEDT

Read it across: New York's column moves between 7 and 9 March while London and Madrid sit still, then London and Madrid move between 28 and 30 March while New York stays at EDT. Sydney doesn't move in March at all: its spring change falls in October.

The 2026 change dates, and the one place with none

  • United States (America/New_York and the other US zones): clocks go forward 8 March 2026, back 1 November 2026.
  • European Union (Europe/London, Europe/Madrid): clocks go forward 29 March 2026, back 25 October 2026, a week before the US falls back, which is the gap that catches people out in late October.
  • Australia (Australia/Sydney): the southern hemisphere runs the opposite way round. Clocks go back (DST ends) on Sunday 5 April 2026 and forward (DST starts) on Sunday 4 October 2026, local time; in UTC both changes happen at 1600Z the evening before.
  • Queensland (Australia/Brisbane) does not observe daylight saving at all: zoneinfo shows zero transitions for it across all of 2026, so its UTC offset stays +10:00 year-round while Sydney, one state over, moves between +10:00 and +11:00.

How E6B Calc shows local and Zulu

The Clocks screen, under Time, shows Zulu, Local and an optional Departure field side by side, 24-hour with seconds and the date for each. Add a departure zone with Set departure time zone when you want a third city next to the two you already see.

A free Zulu Clock widget on the Home Screen and Lock Screen shows just the UTC hours and minutes, no setup, no local time at all.

Where DST actually bites a flight plan

  • Filing a route with last week's offset. The offset you memorised for your home airport two weeks ago may already be wrong; check which side of the change date you're on, not which side you were on last time you flew.
  • Trusting a NOTAM or flight plan time as local. They are published in UTC, full stop, even when the briefing page shows your local time next to it for convenience.
  • Forgetting the date rolls over at 0000Z, not at local midnight. A departure at 2230 local on the US East Coast in winter is already the next date in Zulu.
  • Assuming the whole world changes clocks on the same weekend. The US and EU changes sit three weeks apart each spring and a week apart each autumn; Australia's own change happens on the opposite side of the year.

One honest limit

E6B Calc's Local clock follows the time zone your device is set to, not a time zone you pick for an airport you are only planning to visit. For a city you are not physically in, use Departure field and Set departure time zone, which lets you search and pick any zone regardless of where the phone itself is.

Questions and answers

Does UTC change for daylight saving time?
No. UTC, and Zulu time, which is the same thing, is fixed all year. Daylight saving only changes the offset between UTC and a local clock, never UTC itself.
Why do pilots use Zulu time instead of local time?
Because a route often crosses several zones and DST boundaries in one flight. One UTC time on the plan, the METAR and the clearance means everyone reads the same instant.
Do the US and Europe change their clocks on the same day?
No. In 2026 the US moves forward 8 March and back 1 November; the EU moves forward 29 March and back 25 October: three weeks apart in spring, one week in autumn.
Does every part of Australia observe daylight saving?
No. Sydney and most of the southern and eastern states do, moving between UTC+10 and UTC+11. Queensland does not: Brisbane stays on UTC+10 all year, so for part of the year it shares a clock with Sydney and for the other part it does not.

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