US regulators on Wednesday cleared the Boeing 737 MAX to take to the skies again, ending its 20-month grounding after two fatal crashes.

The carrier's workhorse got the green light from the Federal Aviation Administration but will not fly right away.

Regulators in other countries also want to re-certify the plane. And the FAA said it must approve 737 MAX pilot training program revisions for each US airline operating the MAX.

The plane was grounded after two crashes that killed a total of 346 people last year. The company has since worked to fix a problem with a safety system that was supposed to keep the plane from stalling as it ascends. Instead it caused the noses of 737 MAX planes to point down and led to those crashes.