With ever-improving fuel efficiency and aerodynamics, planes are able to stay in the air for longer than ever before. All major airlines have extended-range aircraft that can make a leg-cramping 14 hour flight with no problem. A few commercial carriers have even been able to stretch their time aloft to more than 18 hours.

Because of wind patterns, route paths, air traffic and other factors, flights that cover the longest distance do not necessarily take the longest amount of time. Favorable west-to-east tailwinds, for example, can make a journey from Sydney to Dallas a whole hour faster than the exact same trip in the other direction.

For fliers, time in the air is what matters the most. About 16 hours in economy class will give you the same amount of “seat numbness” no matter how much distance you’ve covered. Most passengers answer the question “how bad is it going to be?” by glancing at the “flight duration” figures on their itinerary.

So what are the longest flights in the world in terms of time in the air?

Flight attendants

Singapore Airlines flight attendants, with their distinctive uniforms, have won numerous awards. (Photo: Rita Franz/Wikimedia Commons)

In the past year, some changes have occurred in the rankings. Singapore Airlines recently stopped service on two routes that had more than 18 hours of flight time. Both journeys ended at Singapore’s Changi Airport, with one beginning at Newark (19 hours total travel time) and the other at LAX (just over 18 hours aloft).

Despite the marathon length, these flights had something going for them: The planes boasted business-class-only configurations. No passengers had to endure 18 hours of the economy-class blues. Also, the service cut down on fliers' actual travel time — time in the air plus time in the airport. With one or two layovers, the journey from New York to Singapore takes more than 24 hours total. Some two-layover itineraries even cross the 30-hour threshold.  

Thai Airways plane

Thai Airways flights from LAX  to Bangkok take more than 17 hours. (Photo: InSapphoWeTrust/Flickr)

Thai Airways' service from LAX to Bangkok now holds the record for the flight that spends the longest time in the air. The journey takes more than 17 hours on average. Thai is famous for its congenial cabin staff, quality food and generous menu of amenities. But 17 hours is still 17 hours. Interestingly, favorable wind patterns on the return trip from Bangkok to Los Angeles make for a much quicker journey. California-bound passengers get to disembark about 16 hours after taking off from Bangkok Suvarnabhumi.

Two routes from Dubai cross the 16-hour line. Emirates’ flights from its Middle Eastern hub to Houston Intercontinental and to Los Angeles both take longer than 16 hours and cover more than 8,000 miles. Like Thai, Emirates is known for quality service, so fliers can enjoy a slightly higher level of comfort to help them cope with the trip.

Emirates appetizer

Business class fliers with Emirates get upscale meals to make travel more pleasant. (Photo: Kenneth Lu/Flickr)

Australia's flag carrier, Qantas, is also in the ultra-long-haul market. The airline offers two flights longer than 8,000 miles between Australia and Dallas-Fort Worth International Airport: one from Sydney and one to Brisbane. The DFW to Brisbane trip crosses the 16-hour threshold, but the flight that originates in Sydney takes a mere 15 hours to reach its north Texas destination.

One final service that deserves mention in the behind-numbing flight category is from Atlanta’s Hartsfield-Jackson International Airport to Johannesburg. The outbound journey from Atlanta tops out at just more than 15 hours; the return trip breaks the 16-hour barrier. Flown by Delta Air Lines, this is one of the longest flights offered by any U.S.-based carrier.

Because airlines are always on the lookout for new routes where they can eke out a profit, the longest-flight rankings are constantly changing. Dozens of routes hover in the 15- to 16-hour range, and an uncountable number of flights top the 12-hour mark.   

Honolulu airport

The longest flights within the U.S. travel between the East Coast and Honolulu. (Photo: InSapphoWeTrust/Flickr)

If you don't plan to travel abroad, reading about these long air journeys should make you feel better about the amount of time you spend on domestic flights. The longest routes within the U.S. are between the East Coast and Hawaii. Flights from New York to Honolulu on United and Hawaiian Airlines take more than 11 hours.

The longest routes in the lower 48 are between Florida and Seattle. American Airlines flies to Sea-Tac International Airport from Miami, and Alaska Airlines flies from Fort Lauderdale. Both flights are aloft for about 6.5 hours. United, JetBlue and Virgin America are close runners-up. These three carriers offer six-hour-plus service on the heavily traveled Boston to San Francisco route.

The good news: Planes are constantly improving, so in the future, flight times may be lower. Or, failing that, at least the in-flight entertainment and services will be better.

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