Qantas says no aircraft now in service has the range to fly these direct routes with passengers and luggage at full capacity, while the two most likely candidates now in development - Boeing's 777-8X and the Airbus A350-900ULR - "can get close", it says.
"The big positive looks to be the dramatic improvement in both domestic and worldwide revenue per available seat kilometre (RASK) in the fourth quarter and the implications that has into FY18", said Sondal Bensan, an investment analyst at Qantas's biggest shareholder, BT Investment Management.
The underlying result represents the second highest performance in Qantas' 97 year history, down 8.6 per cent compared with last year's record.
The Australian carrier, reporting its second-highest profit on record, said Friday it will repurchase as much as A$373 million ($295 million) of stock even as the shares traded near an all-time high.
"These results mark the completion of our three year turnaround program - the ambitious $2 billion initiative we started in 2014 to make the Qantas Group sustainably profitable", he told the market.
A non-stop Sydney-London route that is three hours shorter than flights involving stops would allow Qantas to charge a premium and differentiate its product from the around two dozen other airlines plying the so-called Kangaroo route with stop-offs in Singapore, Dubai and Hong Kong.
Although down almost 9 per cent from that record, CEO Joyce said the company's turnaround was complete.
Thus a 2022 target date for a new jet to fit the Qantas ambitions for London and NYC may prove problematical, giving Air NZ a long "holiday" from direct competition on a service to the latter destination.
"We tackled some hard structural issues, became a lot more efficient and kept improving customer service".
He said routes linked to mining, such as Perth to Karratha, had been axed, making way for in-demand flights like its recently launched Melbourne to Tokyo service.
It was understood Qantas was seeking an aircraft capable of carrying 300 passengers in both directions on both the NY and London routes.
"We operate in a very competitive environment, so continuous improvement is crucial".
Shares in Qantas rose 3.10 percent to Aus$5.98 in Sydney on Friday.
Qantas chairman Alan Joyce has challenged Boeing and Airbus to build an aircraft that can fly non-stop with a full payload between Sydney and London, New York and Rio de Janeiro by 2022.