sleeping airplane business classJoe Shlabotnik via Flickr

The longest airplane flight with a coach cabin is 15 hours, on Qantas Airways, from Sydney to Dallas, Scott McCartney of The Wall Street Journal reports.

That's a lot of time to be sitting in such a cramped space, but McCartney writes that more and more business travelers and affluent tourists are willing to endure the painful vicissitudes of a long-haul non-stop flight to avoid layovers. They're also willing to pay about 20% more.

As airlines take on longer-range jets with bigger fuel tanks--Boeing and Airbus jets can travel about 9,000 miles before a refill--the possibilities for longer airtime are expanding.

Delta Air Lines offers a non-stop flight to Johannesburg from Atlanta, and Emirates can get to Los Angeles from Dubai. Singapore Air offers a business-class-only flight from Newark or Los Angeles to Singapore. There are 100 lie-flat beds on the plane.

The length? 18 hours. The price? $8,446. A layover costs $1,000 less.

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