Boeing won approval from U.S. regulators on Wednesday (November 18) to put its 737 MAX back in the skies.
It comes after the jet was grounded last year following two fatal crashes.
346 people were killed within five months in 2018 and 2019 when two MAX planes crashed in Indonesia and Ethiopia.
It led to scores of investigations and cost the company around $20 billion.
The subsequent 20-month grounding has been the longest in commercial aviation history.
The Federal Aviation Administration will now demand new pilot training and software upgrades to deal with a stall-prevention system called MCAS.
In both crashes, MCAS repeatedly shoved down the jet's nose as pilots struggled to regain control.
The FAA has also said it would no longer allow Boeing to sign off on the airworthiness of some 450 already-built 737 MAXs.
Instead, it plans on in-person inspections that could take a year or more to complete.
Since the plane's grounding, a number of probes have heavily criticised Boeing's development of the MAX.
A report by the U.S. House of Representatives said it made 'faulty design and performance assumptions'.
It also said Boeing concealed 'the very existence of MCAS from 737 MAX pilots.'
It accused the planemaker of withholding 'crucial information from the FAA, its customers and 737 MAX pilots'.
With a return to service now confirmed, Boeing is taking no chances.
Sources say the company will run a 24-hour war room to keep track of all MAX flights for issues that could impact the jet's return.