KJFK uses Eastern Time (EST/EDT). Learn when to add four or five hours, handle date changes and set UTC correctly in flight simulators.
John F. Kennedy International Airport (KJFK) uses US Eastern Time: Eastern Standard Time (EST, UTC−5) in winter and Eastern Daylight Time (EDT, UTC−4) during daylight saving. To convert KJFK local time to UTC, add five hours under EST or four hours under EDT, carrying the date forward when midnight is crossed.
Is KJFK UTC−4 or UTC−5?
KJFK is UTC−5 on standard time and UTC−4 during daylight saving time. For modern dates, New York normally changes to daylight time on the second Sunday in March and returns to standard time on the first Sunday in November.
| KJFK time | UTC offset | Typical period |
|---|---|---|
| Eastern Standard Time (EST) | UTC−5 | Early November to mid-March |
| Eastern Daylight Time (EDT) | UTC−4 | Mid-March to early November |
The location's time-zone identifier is America/New_York. This is preferable to forcing a fixed EST offset because it applies the daylight-saving rule for the selected date. Historical dates can follow different rules, so use the date rather than assuming that every winter or summer flight has the same offset.
In flight simulators generally—including MSFS, X-Plane, FSX and Prepar3D—the simulated date determines whether KJFK should be on EST or EDT. The season shown outside the cockpit is not a reliable substitute for checking that date.
How do you convert KJFK local time to UTC?
Add four or five hours to KJFK local time, depending on whether EDT or EST applies.
- Check the flight date. Determine whether New York is observing EST or EDT on that date.
- Apply the offset. Add five hours for EST or four hours for EDT.
- Correct the date. If the result passes 24:00, subtract 24 hours and move to the following UTC date.
- Write aviation time clearly. Use four digits followed by
Z, such as2230Z.
| KJFK local time | Calculation | UTC result |
|---|---|---|
| 15 January, 18:30 EST | 18:30 + 5 hours | 15 January, 23:30Z |
| 15 July, 18:30 EDT | 18:30 + 4 hours | 15 July, 22:30Z |
| 15 January, 22:45 EST | 22:45 + 5 hours | 16 January, 03:45Z |
How do I convert UTC back to KJFK local time?
Subtract five hours during EST or four hours during EDT. If that takes the result below 00:00, move to the previous local date; for example, 0200Z on 16 January is 21:00 EST on 15 January at KJFK.
Why can the simulator be one hour wrong at KJFK?
A one-hour discrepancy usually means the wrong daylight-saving offset has been applied. Common causes include using UTC−5 throughout the year, reading “Eastern Time” as EST when EDT is active, or setting the simulator to a different date from the computer or live-weather session.
- Check the simulated date: a July flight at KJFK normally uses EDT, even if the computer's real date falls in winter.
- Distinguish ET from EST: ET is a general label covering both EST and EDT; EST specifically means UTC−5.
- Check UTC versus local display: weather reports and flight plans normally show UTC even when the simulator's clock is set to local time.
- Watch DST changeovers: the spring transition skips an hour, while the autumn transition repeats an hour. A local time within that repeated period can be ambiguous without an EST or EDT label.
- Allow for older software: an old simulator or time-synchronisation add-on may contain outdated daylight-saving rules.
If the simulator clock still disagrees with the expected result, our explanation of simulator, PC and UTC clock differences covers the usual settings conflicts.
Should KJFK flight plans use local time or UTC?
Use UTC for flight plans, METARs, TAFs, operational logs and multiplayer coordination; use KJFK local time mainly for airport schedules and passenger-facing departure times. UTC avoids the repeated or missing local hour created by daylight-saving changes.
A weather timestamp such as 161651Z means the 16th day of the month at 16:51 UTC, not 16:51 in New York. For the wider planning implications, see how simulator flight planning handles time zones. When working out an arrival time, calculate in UTC first and convert to local time only at the end, as shown in our flight ETA calculation guidance.