The Federal Aviation Administration (FAA) said on Tuesday it plans to issue a proposed airworthiness directive for the Boeing 737 MAX in the "near future" to address changes made since the plane was grounded in March 2019 after two fatal crashes killed 346 people.

An official briefed on the matter told Reuters that the FAA is unlikely to unground the 737 MAX before sometime in October. Boeing Co did not immediately comment but has said previously it expects to resume deliveries before Sept. 30 following regulatory approval.

The crisis has cost Boeing more than USD 18 billion, slashed production and hobbled its supply chain, with criminal and congressional investigations still ongoing.

The FAA said the public will have 45 days to comment on "proposed design changes and crew procedures to mitigate the safety issues identified during the investigations that followed the Lion Air and Ethiopian Airlines accidents." The FAA noted there are still some key steps before the plane can resume commercial service.

On July 1, the FAA said it had completed three days of certification test flights on the 737 MAX's automated flight control system.

Final planning is under way for the FAA’s Flight Standardization Board (FSB) and the Joint Operations Evaluation Board (JOEB) review of proposed training for flight crews, based on design changes and crew procedures.

The JOEB will include regulators from Canada, Europe and Brazil and will evaluate minimum pilot training requirements. The FSB will issue a draft report for public comment addressing JOEB findings.

The FAA will review Boeing’s final design documentation to evaluate compliance with regulations and the multi-agency Technical Advisory Board will review the final Boeing submission and issue a report prior to a final FAA determination of compliance.

Boeing agreed to add significant safeguards to a key safety system tied to both crashes, make other software updates and move wiring bundles.