Boeing's 777X, a new generation of the wide-body aircraft, completed its maiden flight on Saturday — marking a milestone for the company struggling through the increasing fallout from two fatal crashes of its best-selling 737 Max. Bad weather postponed an attempt at the first flight on Thursday and again on Friday.

The first flight, which took off from Everett, Washington and landed about four hours later at Seattle's Boeing Field is part of testing that will occur throughout the year as the company works toward winning regulatory approval. That process promises receive more scrutiny after the two crashes of the 737 Max.

Boeing's 737 Max single-aisle jetliners have been grounded since March after the second of two crashes, which together killed 346 people. The crisis hurt its reputation and has deepened in recent months, with the release of internal emails revealing employees boasted about convincing regulators and airlines to approve the 737 Max without costly simulator training and others expressing safety concerns. Earlier this month Boeing suspended production of the planes, a move that has rippled through its supply chain, costing close to 3,000 jobs at one manufacturer.

In remarks after the 777X landed, Stan Deal, who now leads Boeing's important commercial airplane business after his predecessor was ousted in the Max crisis last year, thanked the company's employees and said: "I want them to know we have your back."

Deal said the company is trying to regain the public's confidence and that putting a plane like the 777X "through its paces" shows the world "we know what we're doing" and that it knows how to design safe airplanes.

Boeing had aimed to first fly the 777X, a plane it launched at the 2013 Dubai Air Show, last year but the company faced delays because of snags with the General Electric GE9X engines, the largest aircraft engine in the world. The diameter of the engine fan is 11 feet, a foot wider than a NBA basketball hoop is high off the ground.

The plane is the largest twin-engine jet ever built and has a wingspan so wide — more than 235 feet — it features folding wingtips that reduce that width by more than 20 feet so the plane can fit into various airport taxiways and gates. The 777X-9 is slightly longer than Boeing's most iconic plane: the hump-backed 747, which is fading away as airlines opt for twin-engine aircraft that require less fuel.

The 777X, an updated version of the 777 that first flew commercially in 1995, faces its own challenges. Orders for wide-body jets have slowed and several airlines have signed up for rival Airbus' long-range single-aisle A321XLR planes. The 777X, which lists for $422.2 million although airlines usually receive discounts, can fit up to 426 passengers in a two-class configuration. Boeing had 344 firm orders for the 777X at the end of the third quarter, according to a company filing, and Emirates is its biggest single customer.