US aerospace giant Boeing successfully completed the maiden flight of its twin-engined 777X jetliner, the company said on Saturday.

The 252-foot-long passenger aircraft landed at Boeing Field near downtown Seattle at 2:00 pm local time (2200 GMT, 2300 CET) after flying for more than three hours on Saturday.

The maiden flight of the world's largest twin-engined passenger jet marked the start of a year of testing before it begins intercontinental service in 2021.

The flight was hailed as a major step for the company as it struggles with the fallout from its embattled 737 MAX.

Boeing said the new aircraft would stay in the air for up to five hours. The flight had been delayed twice due to inclement weather, including high-speed winds and rain.

The company said it would formally file for approval from the US Federal Aviation Authority (FAA) if the 777X's first flights were successful.

Read more: Can Boeing return to the skies after 737 MAX disasters?

Sky-high

Boeing has received more than 300 orders for the 777X from several major airlines, including Lufthansa, Emirates and Cathay Pacific.

The company said the Boeing 777X combines design elements from the twin-aisle 777 with "advanced technologies" from the 787 Dreamliner, making it "the largest and most fuel-efficient twin-engine jet in the world."

The aircraft can carry up to 426 passengers and is set to compete with the A350-1000 recently introduced by European rival Airbus.

'Flagship for the big airlines'

Boeing is hoping to make a comeback after aviation authorities across the globe grounded its 737 MAX due to deadly plane crashes in Ethiopia and Indonesia.

Investigators have blamed the crashes on the malfunctioning of an automatic control system during takeoff.

When asked by reporters how issues with the 737 MAX would play out for the Boeing's new line of long-haul aircraft, 777X marketing director Wendy Sowers directed attention to Boeing's future prospects.

"To me, this is the flagship for the big airlines around the world," Sowers said. "It represents the great things we can do as a company."

Read more: Boeing crashes: Can machines make better decisions than people?

shs, ls/rc (AFP, EFE)

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