(CNN) — The globetrotting dream of flying nonstop from London to Sydney has taken a step closer, according to Australian airline Qantas, which says it'll soon choose the aircraft it'll use to complete the journey.
Alan Joyce, CEO of the Australian airline, confirmed he had issued an August deadline for manufacturers Airbus and Boeing to make their "best and final offer."
A modified version of Boeing's upcoming 777-8 and two iterations of Airbus's A350 are in the running for Qantas's "Project Sunrise" program to establish the air link by 2023.
"We're hoping by August to have that proposal in and the price of the aircraft in and the guarantees of the aircraft performance and engine maintenance," Joyce told CNN's Richard Quest at the International Air Transportation Association's annual conference in Seoul this week.
Both Airbus and Boeing were tasked with coming up with a suitable aircraft for the ultra-long-haul journey back in 2017 -- a task that requires manufacturers to push fuel efficiencies to new levels.
Qantas aims to launch its first nonstop flights from Sydney to London in 2023.
The chosen airplane must be capable of meeting the "Project Sunrise" criteria of carrying more than 300 passengers, with a four cabin configuration, from Sydney to London.
The 17,000-kilometer, 21-hour journey would steal the crown for the longest scheduled nonstop passenger service from Singapore Airlines, which claimed it in October 2018 with a relaunched Singapore to New York flight.
The yet-to-be launched Boeing 777-8, which will seat 365 passengers, has previously emerged as one of the strong contenders for the project -- Qantas chose a Boeing 787 Dreamliner for its first ever direct flight from Perth to London, which launched in 2018, with a journey time of 17 hours.
However, Airbus has claimed that it currently has two operational aircraft that could make the London-Sydney journey.
Christian Scherer, Airbus's chief commercial officer, speaking at the IATA conference, said his company had met Qantas' "ultra-long-range flying and high-capacity flying, with the A350."
"Airbus is in a privileged position by having the only new contemporaneous technology aircraft out there," he added, according to FlightGlobal.
Airbus is reportedly proposing an Ultra Long Range (ULR) version of its A350-900 or A350-1000 to Qantas.
Qantas chose a Boeing 787 for its nonstop flights between Perth and London.
A spokesperson for the aircraft manufacturer confirmed to CNN Travel that both variants of the A350 can complete the record-breaking flight, pointing out that its A350-900 ULR currently operates the 9,500-mile Singapore-New York service.
Joyce has said he's confident both Airbus and Boeing's jets could make the trip -- plus other ultra-long connections involving Melbourne, New York, Cape Town and Rio de Janeiro -- although not with a full passenger payload.
Qantas aims for the planes to be delivered from late 2022, with the first flights likely to take off in 2023.
Once they've decided on a suitable aircraft, the Australian flag carrier will have to deal with the small matter of convincing Australia's Civil Aviation Safety Authority to allow pilots to fly for longer time periods.
At present, Australian pilots are capped at 20 hours due to fatigue concerns, but this is said to be under review.
Joyce, whose airline celebrates 100 years in November 2020, said the London-Sydney route would not be created simply as a headline-stealing vanity exercise, but would need to be cost-effective.
"If the business case is not there...we will not do it," he said, adding that he was optimistic, but the airline would be "hard-nosed."