A Boeing 737 MAX jet that took off from Seattle on Monday is en route to the manufacturer’s completion plant in China, two industry sources said, in a sign the model is closer to returning to commercial flights there after a three-year grounding.

The plant in China, used for installing interiors before delivery, opened in December 2018, a few months before a second fatal MAX crash led China to ground the model.

China was the first country to ground the MAX and now is the only major global market where the aircraft is still not in commercial service