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.