Earlier this month, Qantas inaugurated service between Sydney (SYD) and Dallas-Ft. Worth International Airport (DFW), marking the first non-stop service between Australia and the U.S. state of Texas. The 747-400 SYD to DFW flight has a 13:25 departure time and an arrival at 13:50. You could think of it as a 25 minute flight with nearly a full day (about 16 hours) stuffed in between. And it's still not the longest passenger flight.

The Qantas 747-400 used on this flight is an ER, or extended range aircraft that can fly 12,971km (8,060m) with a full load of passengers and cargo. The distance between SYD and DFW is just beyond that range at nearly 14,000km (8600m) but the strong Jetstream heading east allows the flight to be non-stop. On the return, the headwinds force the flight to stop in Brisbane (BNE) for extra fuel before continuing on to SYD.

There are several flights that are scheduled for longer flight times due to track and wind conditions but only 2 flights cover longer distances. Singapore Airlines flies the world's longest flights between Newark, New Jersey (EWR) and Singapore that take the top spot in both time and distance traveled. The Airbus A340-500 used on this flight cruises for nearly 19 hours and covers 15,345km (9,535m) each way. Singapore Airlines also happens to operate the second longest flight with the same type of aircraft. The flight between Los Angeles and Singapore lasts between 17 and 18 hours depending on the direction and flight conditions.

What is your tolerance level on a long flight? Is it 3, 10, 12 hours or longer? If you don't mind spending the better part of a day inside an aircraft that's actually flying (ground delays don't count), you might want to try some of the world's longest non-stop flights. Here's to getting a comfortable seat on one of these: