The Qantas 16h 45m flight from Dallas to Sydney aims for Brisbane, and then turns to Sydney as the plane approaches Australia. (10th longest commercial route in the world).
This allows the plane to land at Brisbane and refuel if the calculations are done wrong. Couldn't find stats on how many times it's had to land in BNE.
Pre-COVID, it was apparently common to try and off-load passengers to single stopover flights to reduce fuel needs (I was one of those passengers, and the crew confirmed it was a regular occurance).
An example is Singapore Airlines' former New York to Singapore flight, which could carry only 100 passengers (all business class) on the 10,300-mile (16,600 km) flight. According to an industry analyst, "It [was] pretty much a fuel tanker in the air."
You might also run into some weather you didn't have to plan for and that changes the prevailing winds at the altitude you were previously cruising at or causes you to divert to fly around it.
This allows the plane to land at Brisbane and refuel if the calculations are done wrong. Couldn't find stats on how many times it's had to land in BNE.
Pre-COVID, it was apparently common to try and off-load passengers to single stopover flights to reduce fuel needs (I was one of those passengers, and the crew confirmed it was a regular occurance).