A non-stop Qantas flight from London to Sydney has taken off from Heathrow.
The Australian airline is using the flight to research the impact of ultra-long haul trips on passengers and crew.
Forty people are on board the Boeing 787-9 Dreamliner which took off at 6am on Thursday for the 19-hour flight to the other side of the world.
A Dreamliner can usually carry between 230 and 300 people.
Currently it is impossible to fly a plane at full capacity from London to cities on the east coast of Australia without stopping to refuel.
Qantas began flying non-stop from London to Perth in Western Australia in March 2018, as it is 1,600 miles closer.
Thursday’s flight is part of Project Sunrise, a bid to operate commercial flights from Sydney to London and New York by 2022 if plane makers Airbus or Boeing can provide a suitable aircraft.
Qantas said all carbon emissions from the test flight will be fully offset.
Those on board are mostly Qantas employees fitted with monitors to track their sleep patterns, food and drink intake and physical movements.
The data will be assessed by researchers at the University of Sydney to assess the impact of the flight on their health, wellbeing and body clock.
A team from Melbourne’s Monash University is working with pilots and crew to monitor melatonin levels before, during and after the flight. Melatonin is the hormone that regulates sleep cycles.
Pilots are wearing a device that tracks brain wave patterns and monitors alertness.
Qantas will also gather feedback from passengers on food choices, stretching and wellbeing zones, and in-flight entertainment.
The airline’s chief executive Alan Joyce said previously: “Ultra-long haul flying presents a lot of common sense questions about the comfort and wellbeing of passengers and crew.
“These flights are going to provide invaluable data to help answer them.”
It will be the second aircraft to fly the route non-stop – the first touched down in August 1989.
Qantas flew a Dreamliner non-stop from New York to Sydney last month as part of Project Sunrise, although the route is around 1,000 miles shorter.
It is due to make a final decision on the viability of Project Sunrise as a commercial flight route by the end of the year.