NEW YORK — US safety regulators have cleared Boeing's 737 Max plane to fly again, ending the jet's 20-month grounding.

The plane was grounded in March 2019 after two fatal crashes that killed 346 people. It was discovered that a safety feature meant to stop the plane from climbing too fast and stalling had improperly forced the nose of the plane down, causing the crashes.

The FAA said the design changes it had required "have eliminated what caused these particular accidents".

FAA chief Steve Dickson said he was "100 percent confident" in the safety of the plane.

"We've done everything humanly possible to make sure" these types of crashes do not happen again," the FAA chief said.

The approval comes roughly a year after Boeing had first hoped but too soon for many of the victims' families.

The FAA action is only the first step in allowing 59 airlines that own the 387 grounded planes to fly them as part of their schedule.

The FAA said in a statement before any of the planes can be flown with passengers again, the necessary changes to the 737 Max identified in the approval process must be installed, the FAA must inspect the individual planes. The pilots must also complete additional training.

Some of the family members of those who died in the crashes have objected to the return to service for the plane. They say Boeing made mistakes in the design of the 737 Max, the newest version of a long-serving plane, which made their version dangerous, and the FAA made mistakes approving the original version and recertifying it to fly now, CNN reported.

"The plane is inherently unstable and it is unairworthy without its software," said Michael Stumo, whose daughter Samaya Rose Stumo died in the March 2019 crash of an Ethiopian Airlines plane. "They haven't fixed it so far. The flying public should avoid Max in the future. Change your flight." — Agencies