The US Federal Aviation Administration (FAA) has started Boeing 737 MAX recertification test flights, marking a major step towards the globally grounded aircraft's return to service.
A 737 MAX aircraft departed from Boeing Field in Seattle on Monday morning for the first round of testing, said the FAA said in a statement, confirming that the administration and Boeing were conducting a series of certification flights this week to evaluate the airplane giant's proposed changes to the fleet's automated flight control system.
The certification flights, which are expected to take approximately three days, will include a wide array of flight maneuvers and emergency procedures to assess whether the changes meet FAA certification standards, reports Xinhua news agency.
The tests were being conducted by test pilots and engineers from the FAA and Boeing.
"While the certification flights are an important milestone, a number of key tasks remain. The FAA is following a deliberate process and will take the time it needs to thoroughly review Boeing's work.
"We will lift the grounding order only after we are satisfied that the aircraft meets certification standards," the FAA said.
More than 800 737 MAX jets have been globally grounded since mid-March 2019 after investigators found flawed flight control software on the aircraft was partially responsible for two crashes in Indonesia and Ethiopia that together killed 346 people.
This crisis has cost Boeing billions of dollars, including the compensation it must pay to victims and airlines.
It also led to the dismissal of the company's CEO, Dennis Muilenburg, and raised questions about the trustworthiness of the company and FAA owing to the rush to approve and begin production of the Max.
Boeing posted a net loss of $641 million in the first quarter of 2020, compared with $2.15 billion in profit in the same three-month period last year, as the COVID-19 pandemic and the worldwide grounding of its 737 MAX aircraft took a heavy toll on its business.
The Chicago-based company has also announced that it plans to slash 10 per cent of its workforce and reduce the production of several of its commercial jet models, including the 737 MAX.