Qantas flights from Sydney to Dallas Fort Worth will become the longest air route in the world after Singapore Airlines announced plan to scrap its Singapore-New York non-stop flights.

Qantas flights from Sydney to Dallas Fort Worth will become the longest air route in the world after Singapore Airlines announced plan to scrap its Singapore-New York non-stop flights. Photo: AP

Singapore Airlines is cancelling the world's longest commercial flight, giving the title to the Qantas flight between Sydney and Dallas.

Singapore Airlines announced on yesterday it would end its nonstop flight between Singapore and Newark, a distance of about 15,000 kilometres.

A slightly shorter route between Singapore and Los Angeles will also end.

The flight from Newark, outside New York, to Singapore takes about 18 hours. The trip from Los Angeles is shorter but takes 18 hours and 30 minutes.

Headwinds over the Pacific Ocean slow the Los Angeles flight. The Newark flight goes over the North Pole and can fly faster. The Newark flight is the longest-distance flight in the world and the Los Angeles one holds the record for duration. The flights started in 2004.

The new titles will go to the 13,650km Qantas flight and the 17-hour Delta flight between Johannesburg and Atlanta.

Singapore Airlines has added more seats to New York and Los Angeles using A380 superjumbos, which have more capacity and less range than A340s. The carrier yesterday said it plans to order five more A380s along with 20 two-engine A350-900s. The deal is worth $US7.5 billion ($A7.2 billion) at list prices, it said.

British aircraft engine maker Rolls-Royce announced on Wednesday that it had been contracted by SIA to supply the engines for the new planes in a deal worth $US2.6 billion.

SIA was the first airline in the world to operate the A380, the world's largest commercial aircraft, and already has 19 of them as part of a fleet of more than 100 Airbus and Boeing planes.

Its long-haul budget airline Scoot, which started operations only in June and flies to several Asian destinations, said it would acquire 20 Boeing 787 Dreamliners with a total list price of more than $US4 billion dollars.

The aircraft orders come two days after SIA confirmed it had temporarily frozen its intake of cadet pilots, the second time in three years that the carrier had put a hold on fresh hiring.

In March SIA encouraged its pilots to go on voluntary leave without pay and work for other companies as it struggles with high oil prices, stiff competition from regional and Middle East carriers and a worldwide aviation slowdown.

SIA's net profit in the year to March slumped 69 percent to Sg$336 million ($A265 million).

"This is a smart move by them to cover all their bases," Justin Harper, an analyst with IG Markets Singapore, said of the announcements by the two carriers.

"They're seeing a slowdown across the globe and people are tightening their belts, and so low-cost travel is definitely here to stay, and they're hoping to ride on the back of that," he told said.

SIA chief executive Goh Choon Phong said the Airbus order will "provide us with additional growth opportunities and is consistent with our longstanding policy of maintaining a young and modern fleet".

Airbus Chief Operating Officer John Leahy said: "This announcement from one of the world's most prestigious carriers underscores the unrivalled comfort and efficiency offered by Airbus wide-body aircraft."

Deliveries for SIA's Airbus orders are due to begin in 2017 while Scoot will receive its first Boeing 787s in 2014, the airlines said.

As part of the deal, Airbus will take back five of SIA's long-haul A340-500s, which will be removed from service by the fourth quarter of 2013.

This will result in the cancellation of non-stop flights between Singapore and Los Angeles, as well as the Singapore-Newark route.

Scoot chief executive Campbell Wilson said the more fuel-efficient Boeing Dreamliners, which will replace four of the carrier's Boeing 777-200s, "will help keep ticket prices low".

Scoot currently operates no-frills flights from Singapore to Sydney, the Gold Coast, Bangkok, Taipei and Tianjin in China.

Services to Tokyo will start on October 29 followed by flights to the Chinese cities of Shenyang and Qingdao in November, the statement said.

The aviation industry is facing turbulence as global economic woes, particularly Europe's debt crisis and the slow US recovery, along with high oil prices bite deep into customers' pockets.

SIA had warned in its June earnings report that the outlook remained gloomy for the rest of the year due to high jet fuel prices, which accounts for 40 percent of its total spending.

The International Air Transport Association earlier this month said it expects global airlines to generate $US4.1 billion in profits collectively this year, less than half the $US8.4 billion seen in 2011.

AFP/AP