Boeing said it has completed the software to fix the flight control issue for the 737 MAX, having tested the updated software on 207 flights for more than 360 hours.
Now it heads to the FAA for review, in consultation with a Technical Advisory Board, before the aircraft can be recertified.
"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," Boeing CEO Dennis Muilenburg said in the statement.
Speaking before Congress Wednesday, Daniel K. Elwell, acting administrator of the Federal Aviation Administration, vowed the agency would take every precaution before returning the MAX to service, though he did not give a timeline for the process.
“In the U.S., the 737 Max will return to service only when the FAA'S analysis of the facts and technical data indicate that it's safe to do so,” Elwell told the House’s Subcommittee on Aviation.
The fleet has been grounded since Mar. 13, after two crashes of Boeing's new 737 MAX in Indonesia and Ethiopia, killing 346 people.
According to preliminary crash reports, the flight control system repeatedly pushed the nose of the jet down after takeoff. It was reportedly caused by bad data flowing into the MCAS system – or Maneuvering Characteristics Augmentation System – triggering the automatic lowering of the aircrafts' noses, and ultimately the fatal dives.
Boeing said the fix will feed MCAS with data from two sensors, opposed to the original one, making the plane less susceptible to a crash because of bad data.
"Boeing has developed enhanced training and education materials that are now being reviewed with the FAA, global regulators, and airline customers to support return-to-service and longer-term operations," the company statement said. "This includes a series of regional customer conferences being conducted around the world."
The FAA will meet with its counterparts in other countries next week, who also grounded the MAX to discuss the process of safety analysis.
Elwell told lawmakers the software installation and training is an agency priority, as will be the roll-out of any software, training, or other measures to operators of the 737 MAX.
Since the grounding, Southwest Airlines and Americans Airlines have had to extend MAX cancellations into August as they wait for the FAA’s recertification. About 100 American Airlines flights per day were affected, while Southwest’s schedule included about 160 flights per day on the aircraft.