A Qantas experimental flight to test the viability of extreme flying took off from London last night and will land in Sydney this afternoon after close to 20 hours in the air.
The brand new 787 Dreamliner has 62 passengers and crew on board for the non-stop flight which followsa New York-Sydney test flight last month.
At 7am this morning Flightradar data showed the plane close to the Philippines with just over seven and a half hours to fly.
The test flights are aimed at studying the effect on those on board. Scientists monitor crew and passengers for research into minimising jet lag for passengers and improving crew wellbeing.
Qantas chief executive Alan Joyce floated the option of redesigned aircraft cabins to include "move and stretch" zones and other social spaces for ultra-long-haul commercial flights.
"We know that travellers want room to move on these direct services, and the exercises we encouraged on the first research flight seemed to work really well. So, we're definitely looking to incorporate on-board stretching zones and even some simple modifications like overhead handles to encourage low-impact exercises."
Qantas will soon make a call on whether on whether to launch commercial flights between Australia's eastern cities and London and New York as part of Project Sunrise.
It is still considering which aircraft to use on commercial flights. Airbus and Boeing have pitched aircraft (the A350 and 777X respectively) and it is still in negotiations with pilots who will crew the ultra-long-range flights.
The London to Sydney flight is scheduled to took off just before 7pm (NZT) and while it ran into headwinds initially favourable winds over China are keeping it on course for a flight of just over 19 and a half hours. It will cover 17,800km and flight planners say it could take as long as 20 and a half hours.
It comes almost 100 years to the day the first London to Australia flight operated from Hounslow Heath (near today's Heathrow Airport) to Darwin, a journey that took 28 days.
Today's flight is a re-purposed delivery flight although it is not the first non-stop journey from London to Sydney.
Thirty years ago a Boeing 747, which had not had its cabin fully fitted and used special high-density fuel, made the trip. That flight had just 23 people on board.
The Jumbo used about 180 tonnes of fuel on that flight, whereas the twin-engined Dreamliner will burn just over half as much.
The new plane will have a maximum fuel load of 126,000 litres and is expected to have 7500 litres left when it lands. That translates to 100 minutes of flight time.
Airlines are under intensifying pressure from environmentally aware travellers but say all carbon emissions from this and two New York-Sydney research flights will be offset.
Qantas this week announced it was effectively doubling current levels of flight offsetting, capping carbon emissions from 2020 onwards and aimed to totally eliminate net emissions by the year 2050.
Qantas first started flying between London and Sydney in 1947. It took five days and six stops.
The flight today will travel at 85 per cent the speed of sound - about 930km/h.
Cruising altitude will start at 35,000 feet (10km) and as the aircraft weight reduces with fuel burn, the cruising altitude will increase to 40,000 feet.
Last year the airline started London to Perth non-stop flights, which take about 17 hours.
Joyce said that flight was a big leap forward.
''The final frontier is New York and London to the east coast of Australia non-stop and we are hopeful of conquering that by 2023 if we can make all elements of the business case stack up.''
Today's flight will fly over 11 countries: England, Netherlands, Germany, Poland, Belarus, Russia, Kazakhstan, China, Philippines and Indonesia before crossing the Australian coast near Darwin, tracking across the country before descending into Sydney.
Researchers from the University of Sydney's Charles Perkins Centre as well as the Cooperative Research Centre for Alertness, Safety and Productivity (Alertness CRC) will be collecting passenger and crew data.
Professor Corinne Caillaud, from the Charles Perkins Centre, said that data from all three flights would be used for the analysis, but feedback from participants on the first New York to Sydney flight suggested the changes trialled would be welcomed by passengers.
"We are hopeful that the interventions and strategies we tried on the first research flight helped passengers better manage the challenges of crossing multiple time zones. From a research point of view, it was something quite novel.
In this second flight, passengers will eat supper at breakfast time, with the aim of encouraging them to sleep at 10am in the morning London time to help avoid light and reset their body clock to Sydney time.
Passengers will board at 6am London time. After take-off they will be offered a range of high GI supper options such as chicken broth with macaroni or a steak sandwich, along with a glass of wine and a milk-based panacotta dessert.
Cabin lighting and temperature, stretching and meditation will also play key roles in the research.