In a step towards reviving the plane model after two fatal crashes forced grounding for more than two years, a Boeing 737 Max jet departed for China to conduct a flight test for regulators, sources said.

At around 8am local time, the 737-7 took off from Seattle’s Boeing Field, and initially bound for John Rodgers Field outside Honolulu, according to FlightRadar24, a flight-tracking site. Boeing refused to comment on the flight or activity in China.

“Boeing continues to work with global regulators as they complete their validation processes in order to better understand enhancements to the airplane,” the company said in an emailed statement.

Boeing’s shares recovered from a morning slump after news of the flight broke, rising as much as 1.4 per cent. Boeing had climbed seven per cent this year through Tuesday, about half the gain of the Dow Jones Industrial Average.

The Hawaii flight is the first leg of a trip across the Pacific, sources said. With the Max also barred from Russian airspace, the narrow-body plane will travel near the equator to China rather than take the shorter northern crossing that is typically flown by commercial aircraft.

While the Max’s validation flight in China would be a milestone, the regulators still could take months to wrap up their work before allowing the plane to resume commercial service. Boeing sent a delegation of around 35 pilots and engineers to the nation last month to meet with regulators and prepare for simulator and flight testing.

US Federal Aviation Administration’s technical officials have just completed a quarantine in China – required due to the Covid-19 pandemic – and are expected to participate in the test programme, a source said.

The FAA is the government agency responsible for approving the plane’s operation in the US and it oversaw efforts over 18 months to redesign systems on the jet while it was grounded.

The stakes are enormous for Boeing, which has not logged a major jet order from China in years as trade tensions simmered. The resumption of Max deliveries would bolster the company’s plans to speed production of its principal money-maker as demand recovers from a global pandemic and a worldwide flying ban on the model.

About 175 nations have cleared the Max to resume service after Boeing paid over $2.5 billion in fines and redesigned a flight-control system linked to crashes in late 2018 and early 2019 that killed 346 people.

Chief executive Dave Calhoun has been upbeat about prospects for the planemaker and the Max in China, after US Deputy Secretary of State Wendy Sherman travelled to the country for diplomatic meetings.

The Max will be cleared to fly in China and the rest of the globe by year-end, Mr Calhoun said during the company’s earnings call last month. With the 2022 Winter Olympics in Beijing looming and the effects of the pandemic hopefully receding, China’s airlines are clamouring to get the Max back in service, he said.

Talks with the country’s air regulator, Civil Aviation Administration of China, have been encouraging and constructive, Mr Calhoun said.