Sydney - Qantas still plans to launch non-stop flights from Sydney to London and New York within five years, but the goal of transporting more than 300 passengers per flight has turned out to be too ambitious for now, according to CEO Alan Joyce.

The Australian flag carrier has been talking to Airbus and Boeing for a while about the airline's need for an aircraft that can serve such long flights. Two choices have emerged from these discussions: the Boeing 777X and Airbus A350-1000ULR which are both still under development.

It has now become clear that both aircraft cannot fly from Sydney to London 20 hours with full capacity.

Our belief is ultra-long-haul flights are not going to be full passenger payload and freight, but there is sufficient capability to make it commercially viable,
Joyce told South China Morning Post.

Qantas plans to order the 777-8 or A350-1000ULR by the end of 2019, targeting deliveries between 2022 and 2023.

Boeing and Airbus compete for "Project Sunrise" of Qantas

Currently, the only non-stop flight from Australia to Europe served by Qantas is Perth-London route that is flown by the Boeing 787-9 with a flight duration of a little more than 17 hours.

Singapore Airlines is the only airline serving on the longest route of the world between Singapore and New York, which lasts nearly 18 hours. But the flight has only business and premium economy seats.