Australian airline Qantas tested the world's longest flight, a record-breaking 19 hour and 16-minute flight, from New York to Sydney.
The research flight carried a total of 49 passengers and crew and ran experiments to assess the health of those on board.
The airline said they had monitored "pilot brain waves, melatonin levels and alertness". The flight also tested cabin lighting and adjusting in-flight meal timing to reduce jetlag. They also included exercise classes.
"This is a really significant first for aviation. Hopefully, it’s a preview of a regular service that will speed up how people travel from one side of the globe to the other," said Alan Joyce, Qantas Group's CEO who was one of the people on board the flight.
“We know ultra long haul flights pose some extra challenges but that’s been true every time technology has allowed us to fly further. The research we’re doing should give us better strategies for improving comfort and wellbeing along the way."
Qantas captain Sean Golding led the four pilots operating the service.
"The flight went really smoothly. Headwinds picked up overnight, which slowed us down to start with, but that was part of our scenario planning. Given how long we were airborne, we were able to keep optimising the flight path to make the best of the conditions," Golding said.
Joyce explained in a statement that night flights usually start with dinner, but for the research flight they started with lunch and kept the lights on for the first six hours, which matched the time of day at the destination.
The group is planning two more research flights from London to Sydney in November and New York to Sydney in December. Qantas will decide in December about whether or not the ultra-long-haul flights will enter into service.
Qantas says those flights' emissions will be fully offset.
"We had a lot of interest from air traffic controllers as we crossed through different airspace because of the uniqueness of this flight. We also had a special sign off and welcome home from the control towers in New York and Sydney, which you don’t get every day," said Qantas captain Golding.