Booking flights can sometimes feel like solving a math puzzle—especially when multiple time zones or daylight saving changes are involved. The potential for confusion (or even a missed flight) can seem high.
To make things trickier, daylight saving time (DST) doesn’t happen everywhere—or at the same time. For instance, the United Kingdom turns clocks back an hour on the last Sunday in October, while the United States waits until the first Sunday in November. Many regions, such as Hawaii and parts of Arizona, don’t observe daylight saving at all.
Fortunately, travelers don’t have to do any calculations themselves. Airlines handle all the time zone and daylight saving adjustments automatically. According to Dr. Ahmed Abdelghany, professor and associate dean at Embry-Riddle Aeronautical University’s O’Maley College of Business, there’s “zero error from the airline side.”
How Airlines Calculate Flight Departure and Arrival Times
Behind the scenes, airlines rely on Coordinated Universal Time (UTC) for all internal operations. However, the times displayed to travelers—on tickets, websites, and departure boards—are always shown in local time.
“All airlines use the same universal static file that contains the time zones of every destination and origin for their flights,” explained Abdelghany. “The calculation is very simple. You find the block time—meaning gate-to-gate duration—and then add or subtract the time zone difference.”
That’s why a flight departing California at midnight might arrive in New York around 8 a.m., despite the flight only lasting about five hours. The schedule accounts for both the three-hour time difference and the flight duration.
For routes where daylight saving isn’t observed—say, from Hawaii to California—the flight might appear to arrive an hour later, even though the actual journey time remains unchanged. This happens because arrival times are displayed in the local time zone of the destination.
Do Travelers Need to Calculate Time Changes?
In short: No. Airlines have already done the math. Travelers just need to note that:
- Departure times are based on the local time of the departing airport.
- Arrival times are shown in the local time of the destination airport.
However, passengers should stay aware of local daylight saving changes—especially if traveling right after clocks shift.
“I can assure you that the error will come from the passenger who’s not aware that the clock has to be changed in my home overnight,” said Abdelghany.
How Daylight Saving Affects Flights
Daylight saving time doesn’t disrupt flight schedules because airlines automatically update their systems to reflect time changes.
For example, a flight that arrives at 9 p.m. before the time change will show as 8 p.m. after the clocks move back—though it’s the same flight and the same duration.
Travelers just need to ensure their devices are up to date. “You have to make sure that, especially if you’re traveling the next day, you adjust your clock,” Abdelghany advised.
