The next major step is a certification flight with FAA representatives, although that is yet to be scheduled. That flight has not yet been scheduled.
In crashes in Indonesia and Ethiopia, an automated system called MCAS mistakenly turned the noses of the planes down in response to faulty readings from a single sensor. A total of 346 people died in the two crashes.
Management at Boeing, according to an investor note from Morgan Stanley, have found a "degree of optimism" as talks with customers and regulators proceed around getting the 737 MAX flying again, "which could potentially occur over the coming months". Boeing has disclosed an initial financial hit of $1 billion USA to fix the plane, and new Max jets are parked at its Seattle-area factory and elsewhere because deliveries have stopped.
The FAA, regulators from around the world, and airlines are still reviewing plans for additional pilot training.
On Wednesday, acting FAA Administrator Dan Elwell said he expected Boeing to make its formal submission for its software update in the next week or so.
MCAS software tells the flight control system to change its Angle of Attack (AOA) downward if a stall risk is perceived.
Boeing has completed the software update to the Boeing 737 MAX.
"We have completed all of the engineering test flights for the software update and are preparing for the final certification flight", said Muilenburg.
Boeing developed the Max early this decade to compete with a jet from its European rival Airbus that was winning over airline customers with its better fuel efficiency.
Boeing has finished the Boeing 737 MAX's Software Update.
Capacity planning for the current financial year which ends in March 2020 does not include any new B-737 Max jets for SilkAir, said Singapore Airlines (SIA) chief executive Goh Choon Phong on Friday (May 17).
"When I first heard of this, (I) thought that the MCAS should have been more adequately explained in the ops manual and the flight manual", Elwell said. "That's the reason that we had this crash".
The proposed fix, which addresses a problem with a flight handling system thought to be a factor in both crashes, must now win approval from U.S. and global regulators before the planes can return to service.
On the pilot training and error front, NTSB Chairman Sumwalt placed the responsibility firmly on Boeing: "If an aircraft manufacturer is going to sell airplanes all across the globe, then it's important that pilots who are operating those airplanes in those parts of the globe know how to operate them", he said.
Quickly reintegrating Boeing's 737 MAX, a fast-selling model because of its fuel efficiency, longer range, and passenger capacity, is crucial for optimizing airlines' routes and improving margins after having to cancel thousands of flights.
The airlines, which must still decide on pilot training, have said they would use the jets as spare planes if they are approved for flight before those dates.