Boeing has received approval for the return of its 737 Max jets to commercial service.
The Federal Aviation Administration announced its decision late Wednesday to lift the grounding order and clear the jets for use.
The approval comes 20 months after the jets' forced grounding following two crashes that killed 346 passengers and crew. The administration said it had rescinded the grounding order.
"The Federal Aviation Administration's directive is an important milestone. We will continue to work with regulators around the world and our customers to return the airplane back into service worldwide," Boeing's chief executive officer of commercial airplanes Stan Deal said in a statement.
Last week, the administration said that it was in the final stages of reviewing the design changes and fixes to the 737 Max Jets. Federal Aviation administrator Steve Dickson said he would only lift the grounding order if all safety experts were convinced the jets meet all certification standards.
The administration is also approving the delivery of newly built 737 Max aircraft to customers. The new jets will have all the design changes and fixes preinstalled. The administration added that all new jets would need to pass its certification process and each will need to have its own airworthiness certificate before being shipped.
Boeing said that all pilots would need new training to become familiar with the design changes. The company and the administration plan to release a new airworthiness directive within the week.
Since the jets were grounded, the administration and other international aviation regulators have scrutinized the company's operations and the jet's systems. Months of congressional hearings in the U.S. were held to identify the cause of the crashes.
Boeing was criticized for lax safety protocols and the administration was also blamed for allowing these issues to go unnoticed. Boeing fired its CEO and developed fixes for the autopilot systems.