Boeing says it has finished with its updates to the flight-control software implicated in two deadly crashes involving its 737 Max, moving a step closer to getting the plane back in the sky.

Aviation regulators still have more questions about how pilots interact with the plane's controls under different circumstances, and Boeing says it is providing that information.

The next major step is a certification flight with Federal Aviation Administration representatives on board. Boeing said Thursday that flight has not yet been scheduled.

In crashes in Indonesia in October and Ethiopia in March, an automated system called MCAS mistakenly turned the noses of the planes down in response to faulty readings from a single sensor. Pilots were unable to recover; 346 people died.

“With safety as our clear priority, we have completed all of the engineering test flights for the software update and are preparing for the final certification flight,” said Boeing Chairman, President and Chief Executive Officer Dennis Muilenburg. “We’re committed to providing the FAA and global regulators all the information they need, and to getting it right. We’re making clear and steady progress and are confident that the 737 MAX with updated MCAS software will be one of the safest airplanes ever to fly. The accidents have only intensified our commitment to our values, including safety, quality and integrity, because we know lives depend on what we do.”

(The Associated Press contributed to this report.)