Nonstop passenger flights between London and Sydney are set to begin in late 2025. The flight is likely to take 19 hours southbound and up to two hours longer northbound, due to the effects of the jet stream. But its success will depend on Russian airspace reopening.

The shortest path between Heathrow and Australia’s largest city is about 16,800km (10,570 miles).

The London-Sydney flight will be more than 1,600km (1,000 miles) longer than the world’s current longest commercial route, connecting Singapore and New York.

Qantas has announced an order for a dozen Airbus A350-1000 specially adapted jets that will be used for new nonstop links from Sydney to both London and New York. The latter route, measuring 15,900km (9,940 miles), is mostly across the Pacific and US airspace.

The Australia airline launched nonstop flights between Heathrow and Perth, covering 14,500km (9,009 miles), in 2018. They were suspended for two years due to the coronavirus pandemic but resumed in March.

The original plan was for the ultra long-haul flights to begin in early 2023. But the Covid crisis – and the accompanying closure of Australia’s borders for almost two years – set so-called “Project Sunrise” back.

The new link will depend upon Russian airspace being reopened to western airlines. The most direct route between London and Sydney passes close to Moscow.

A more southerly route to avoid overflying Russia would add at least 800km (500 miles) and one hour to the flying time, which could affect the payload the aircraft could carry and its financial viability.

Qantas has been planning Project Sunrise for five years. It first flew nonstop from London to Sydney in 1989, and further publicity flights took place in 2019.

The airline chose the A350 ahead of the latest Boeing 777X. Airbus will add an additional fuel tank and slightly increase the maximum takeoff weight for the new link.

The aircraft manufacturer sent a specially decorated A350 to Sydney for the launch, emblazoned “Our Spirit flies further” and “#LongRangeLeader”.

The Qantas chief executive, Alan Joyce, believes that demand for a nonstop UK-Australia link will be higher than ever due to concerns about intermediate stops in the coronavirus era.

Nonstop flights this year between London and Perth are proving extremely popular because they avoid other nations’ travel restrictions.

Mr Joyce said: “For more than 100 years, Qantas has been at the forefront of transforming the way the world travels, particularly through direct flights.

“Now, the A350 and Project Sunrise will make almost any city in the world just one flight away from Australia. It’s the last frontier and the final fix for the tyranny of distance that has traditionally challenged travel to Australia.”

He said that while the first flights would link Sydney with London and New York, direct connections to destinations such as Paris and Frankfurt would be possible in the future.

The aircraft will be fitted with 238 seats, which Qantas said was the lowest compared with any other A350-1000 currently in service, and more than 40 per cent of the cabin will be dedicated to premium seating. There will also be a ‘Wellbeing Zone’ on board.

Sean Moulton, the airline schedule analyst, said: “Covid makes ultra long-haul routes more attractive, omitting a stop in case border rules change.

“Qantas could grow on its very successful Perth-London route by adding nonstop flights to Sydney and Melbourne.”

Ultra long-haul flights between the UK and Australia are more damaging to the environment than one-stop links, because of the sheer weight of fuel they must carry. Qantas says the new flights “will be carbon neutral, with all emissions offset”.

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