Four engines out - Large twin engine aircraft are in - Curt Lewis

Four-Engine Jumbo Era Nears End as Biggest Airbus A350 Takes Off

The biggest version of Airbus Group SE's A350 wide-body jet will make its first flight Thursday, swelling the twin-engine model's capacity and casting further doubt on the future of four-turbine planes including the manufacturer's own A380 and the Boeing Co. 747.

The A350-1000, due to depart Airbus's base in Toulouse, France, mid-morning local time, seats 366 people in three classes. That's just 44 fewer than the latest version of the 747, and with a vastly improved fuel burn thanks to the new aircraft's two engines and composite construction.

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So-called twinjet planes have become the mainstay of inter-continental travel, with the A350, the baseline version of which had its first commercial flight in 2015, following on from the slightly smaller Boeing 787. Both models have built on inroads made by the U.S. company's 777, which began eating into markets previously restricted to four-jet models fully two decades ago and seats 364 people in three classes with No. 1 operator Emirates of Dubai.

Before the advent of the so-called "big twin" aircraft, older two-engine wide-bodies such as the 767 and A330 were limited to medium-haul markets such as the north Atlantic, partly because of practical limits on how far they could fly in the event of one turbine failing. The 777 cast off those shackles by winning certification for flights as far as three hours from the nearest airport.

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The standard A350-900 has U.S. Federal Aviation Administration approval for up to five hours or 2,000 nautical miles of diversionary flying on a single engine, making possible trips from Southeast Asia and Australia to the U.S. In a denser configuration the new -1000 will be able to carry 440 people, less than 100 short of the A380 superjumbo's standard 525-passenger payload, though the double-decker could accommodate as many as 800 seats in a single class.

The airline industry's appetite for bigger twin-engine planes was revealed when Airbus scrapped a shrunken A350-800 variant, which was deemed too small at 280 seats, and opted instead to upgrade the A330 for shorter routes.

Bigger Boeings

Boeing is also adding more seats to its 777, with new slimline berths taking the total on the long-range 777-300ER to 396 while still retaining three classes.

Twinjet capacity will increase still further with the 777X upgrade of the best-selling wide-body from 2020, the largest of which will seat as many as 425 people in three classes, with a bigger version under consideration able to take upwards of 450 travelers, making it a true jumbo in its own right.

All told, the A350, 787 and 777 have unfilled orders totaling more than 1,950 planes, versus just 29 for the 747 and 121 for the A380. The Airbus A340, which emerged around the time of the 777, has already ceased production, though the lower oil price is prolonging its active life with some carriers.

The A350-1000's debut flight means Airbus has met its goal of getting the model into the air before the end of 2016, with Qatar Airways Ltd. scheduled to be the first carrier to deploy the aircraft next year. The manufacturer is still racing to deliver the 50 A350-900s promised this year amid delays in the supply of interior fittings from suppliers including Paris-based Safran SA.

Airbus's next challenge may be to decide whether to develop a further stretch of the A350 to combat the revamped 777.

That option is emerging as more attractive than upgrading the A380, which appears to have few enthusiasts beyond Emirates, while the A350-1000 has attracted only 196 orders, versus about 600 for the baseline version, suggesting customers may be holding out for a bigger model.