A look inside Qantas' London-Sydney test flight

Qantas has completed what could one day be the world's longest commercial flight.

Passengers on this Boeing 787 Dreamliner spent more than 19 hours up in the air, in a research-flight from London to Sydney.

Passengers and crew were monitored throughout the journey, to see how humans fared on an ultra-long haul flight.

Corinne Caillaut was an assistant professor on board:

(SOUNDBITE) (English) UNIVERSITY OF SYDNEY CHARLES PERKINS CENTRE, ASSISTANT PROFESSOR, CORINNE CAILLAUT, SAYING:

"What we've done basically […] is to design three very important things on the flight. First, the lighting, then the meal schedule and the meal composition, and physical activity onboard. And why we are doing on this very long flight, to help people to adjust better when they arrive in Sydney and to reduce jet-lag on arrival."

It's being called 'Project Sunrise' - CEO Alan Joyce marvelled at having seen a "double sunrise" on the flight, and said the design of the plane would help combat the fatigue of long journeys:

(SOUNDBITE) (English) QANTAS CHIEF EXECUTIVE, ALAN JOYCE, SAYING:

"So our intention is to have a bigger seat pitch in economy than we've ever had before, have dedicated stretching areas in economy, so it is a very designed product for long-haul travel like Sydney-London and Sydney to New York."

It could be a game-changer for the Australian airline - analysts forecast non-stop flights from Sydney to London and New York - could add over 120 million US dollars to annual profits.

If the company charges a premium for cutting out a stop-over.

Passengers on board seemed to think it would be worth it:

(SOUNDBITE) (English) RESEARCH PASSENGER, ANDY CHEVIS, SAYING:

"I actually feel fantastic, I feel really well. Probably a lot better than I normally would at this point in the flight, to be honest."

Qantas is yet to place an order for planes capable of the flight, even if they do the first commercial flight wouldn't be until 2023.