US aviation safety regulators on Tuesday released pilot training protocols for the Boeing 737 MAX, moving the grounded jet one step closer to returning to the skies.

The Federal Aviation Administration published the standards incorporating recommendations from a board of civil aviation regulators from the United States, Canada, Brazil and the European Union. The agency is seeking public comment through November 2.

Although Tuesday's action by FAA is "an important step," the agency reiterated that "several key milestones" remain before the plane can be returned to service.

FAA chief Steve Dickson last week piloted a Boeing 737 MAX test flight, moving the grounded plane closer to regulatory approval to return to service FAA chief Steve Dickson last week piloted a Boeing 737 MAX test flight, moving the grounded plane closer to regulatory approval to return to service Photo: GETTY IMAGES NORTH AMERICA / POOL

These include a review of Boeing's final design documentation to confirm compliance with FAA regulations.

The MAX has been grounded since March 2019 following two crashes that killed 346 people.

FAA chief Steve Dickson last week said he was pleased with a 737 MAX test flight he piloted, but emphasized that more work was needed before the jet is returned to service.