Boeing's delay to development of the long-range 777-8 will not necessarily rule the US airframer out of Qantas's high-profile 'Project Sunrise' initiative to acquire an aircraft capable of operating non-stop services between Sydney and London.

FlightGlobal understands, from a source close to the initiative, that Boeing is keen to remain within the Project Sunrise competition and has put a "compelling option" to the Australian carrier intended to "help manage potential timing issues".

Boeing has been offering the 777-8 as an alternative to the Airbus A350 to serve the 'kangaroo' routes between the UK and eastern Australia. Qantas already uses Boeing 787s on a non-stop route between London and Perth.

Qantas states that it is continuing to work with both Boeing and Airbus on Project Sunrise.

"We have the best-and-final offers from both manufacturers, which is a key part of helping finalise our internal business case," says the carrier.

"We still expect to make a decision by the end of this calendar year.”

Airbus declines to give details on its discussions with Qantas, citing confidentiality reasons. It notes that Qantas has been in discussions with pilots' representatives concerning 22h flights.

It claims that the A350 is the "perfect solution" for Project Sunrise, and says the aircraft would be capable of operating to London from either Sydney or Melbourne.

"As a leading aircraft manufacturer, we are always looking at ways to develop our products," it says, pointing out that an ultra-long range version of the A350-900 – known as the -900ULR – already serves Singapore Airlines' route to Newark.

Airbus previously indicated, earlier this year, that either the -900 or the larger -1000 could be used for Project Sunrise, although the airframer has yet to confirm development of a -1000ULR version.