Roster UTC to local time: the crew conversion guide

Why rosters use UTC

UTC - Coordinated Universal Time - is a fixed time reference that does not change for daylight saving. It is the same in January and July, and it is the same in London, Dubai, and New York. Aviation runs on UTC because it removes ambiguity: when air traffic control, aircraft systems, crew scheduling, and maintenance all use the same reference time, there is no room for local time mismatches to cause operational errors.

Your roster may show UTC explicitly, or it may use "Z" or "Zulu" - these are all the same thing. A report time written as 0600Z means 06:00 UTC. Whether that is 06:00, 07:00, 08:00, or 02:00 in your local time depends on your time zone and the time of year.

How to read Z/Zulu time

The Z suffix means UTC. To convert to local time, add (or subtract) your local UTC offset. If your offset is positive (most of Europe, the Middle East, Asia), you add hours. If your offset is negative (the Americas), you subtract hours.

Example: a 0530Z report time at LHR during summer (BST, UTC+1) is 0630 local. The same 0530Z report time in winter (GMT, UTC+0) is 0530 local. The same report time at DXB (UTC+4, no daylight saving) is 0930 local year-round.

The conversion is simple arithmetic - the trap is remembering to check whether you are currently in summer or winter time, and whether the day your duty falls on is before or after the clock change.

UTC offsets for common crew bases

Here are the UTC offsets for bases where many crew are based. Summer refers to the period when daylight saving is in effect (clocks forward), winter is standard time (clocks back).

London (LHR): UTC+1 summer (BST), UTC+0 winter (GMT)

Stockholm (ARN): UTC+2 summer (CEST), UTC+1 winter (CET)

Copenhagen (CPH): UTC+2 summer (CEST), UTC+1 winter (CET)

Oslo (OSL): UTC+2 summer (CEST), UTC+1 winter (CET)

Dubai (DXB): UTC+4 year-round (no daylight saving)

Doha (DOH): UTC+3 year-round (no daylight saving)

New York (JFK): UTC-4 summer (EDT), UTC-5 winter (EST)

Note that the US and Europe do not change their clocks on the same date - there are a few weeks each spring and autumn where the offset between European and US time zones is temporarily different from the rest of the year.

Summer/winter time changes and where crew go wrong

The clock changes in Europe happen on the last Sunday in March (clocks forward one hour, lose an hour of sleep) and the last Sunday in October (clocks back one hour, gain an hour). In the US, the dates are slightly different.

The most common mistake is applying the wrong UTC offset for dates close to a clock change. If your roster was published before the clock change and you are converting times manually, double-check that you are using the correct offset for each specific date - not just the offset that applies today.

A subtler trap: if you operate a duty that crosses the clock change (for example, a night flight that departs before the clocks go back and lands after), the times on your roster are still UTC throughout. The local time at departure and the local time at arrival are different from each other because the offset changed mid-flight. Your FDP is still calculated in UTC regardless of local clock changes.

See our full standby guide for how UTC reporting times interact with standby activation.

Why missing a briefing because of UTC confusion is more common than it should be

Crew scheduling systems show times in UTC. Phone calendar apps default to local time. If you manually add a duty to your calendar from your roster and enter the UTC time without converting it, your phone will treat it as local time - which means your alarm goes off an hour (or more) late. This is a surprisingly common way to be late for briefing, and it is entirely avoidable.

The safest approach is to either convert every time before entering it in your calendar, or use a roster app that handles the conversion automatically. Layvr converts UTC times to your local time zone when you import your roster, so the times you see in the app are always the local times you need to act on.