Would you fly on a 20-hour non-stop flight?

Qantas is testing direct flights from New York and London to Sydney

Ultra long-haul flights could be about to get even longer as Qantas Airways  trials non-stop, 20-hour journeys.

The Australian airline will test direct flights from New York and London to Sydney. These will carry Qantas employees to see how passengers and crew would fare on such lengthy trips.

The three Boeing 787-9 Dreamliner flights are part of a three-month initiative Qantas is calling "Project Sunrise" and will take place in October, November and December.

Qantas wants to launch the world's longest service by 2022 and the test flights are being used to help the airline gather data about passenger health during a 20-hour journey.

About 40 volunteers will be involved in the test flights. They will sport wearable technology and undergo a host of medical checks and assessments before, during and after travelling.

Scientists and medical experts will monitor sleep patterns, food and beverage consumption, lighting, physical movement and in-flight entertainment to assess the journey's impact on passengers' well-being and body clock.

Carbon emissions from each of the test flights will be fully offset by Qantas.

"Flying non-stop from the east coast of Australia to London and New York is truly the final frontier in aviation, so we’re determined to do all the groundwork to get this right," said Qantas chief executive, Alan Joyce.

If launched, the services would be the world's longest direct flights. This title is currently held by Singapore Airlines which has a 19-hour service from Changi Airport to New York.

Qantas is no stranger to ultra long-flights; the airline launched a 17-hour, non-stop service from Perth to London last year.