Bjorn Fehrm, an aeronautical and economic analyst at Leeham News, explains to CNN the appeal of the ultra-long-haul flight, as opposed to a more typical two-part journey stopping in Dubai or Singapore.
If the flight comes to be, it's unlikely to significantly change the aviation industry, he says, pointing to the existing 17-hour flights between Singapore to NY operated by Singapore Airlines.
The test flights will not be open to regular passengers.
The tests will be the world's first flight by a commercial airline direct from NY to Sydney and only the second time a commercial airline has flown direct from London to Sydney.
The flying kangaroo airline said travellers could fly uninterrupted in 19 hours to some of the world's most popular cities and be spared from having to change flights or disembark while jets were refuelled.
They will be used to track the health and wellbeing of passengers and crew members on board the approximately 19-hour long flights and will be conducted in October, November and December using Boeing 787-9 aircraft. Qantas still hasn't decided on a Boeing or Airbus plane that can fly the route fully laden and without a break.
Monash University scientists will focus on the flight crew, recording their melatonin levels before, during and after the flights, as well as studying brain wave data from electroencephalogram devices worn by the pilots.
Qantas previous year introduced the first direct service from the western Australian city of Perth to London, with the 17-hour journey one of the longest passenger flights in the world.
The tests are part of Project Sunrise, the airline's ambitious plan to operate regular flights from the east coast of Australia to London and NY.
Qantas chief executive Alan Joyce said the flights will give medical experts the chance to do real-time research.
"No airline has done this kind of dedicated research before and we'll be using the results to help shape the cabin design, inflight service and crew roster patterns for Project Sunrise", he said.
Project Sunrise - the name is a nod to the Catalina flying boats operating between Perth and the country now known as Sri Lanka during World War II - was launched in August 2017.
Researchers from Sydney University's Charles Perkins Centre, Monash University and the Alertness Safety and Productivity Cooperative Research Centre - a scientific program backed by the Australian government - will examine the impact of the long flight on those on board. Its underlying pre-tax profit took a hit by a $614 million increase in fuel costs from higher oil prices.