In its report issued Friday, the panel made 12 recommendations for improving the FAA's certification of new aircraft, including more emphasis on understanding how pilots will handle the increasing amount of automation driving modern planes.

The report, called a joint authorities technical review, focused on FAA approval of a new flight-control system called MCAS that automatically pushed the noses of Max jets down — based on faulty readings from a single sensor — before crashes in Indonesia and Ethiopia that killed 346 people.

During the certification process, Boeing changed the design of MCAS, making it more powerful, but key people at the FAA were not always told. The review committee said it believed that if FAA technical staff knew more about how MCAS worked, they likely would have seen the possibility that it could overpower pilots' efforts to stop the nose-down pitch.

MCAS evolved "from a relatively benign system to a not-so-benign system without adequate knowledge by the FAA," the panel's chief, former National Transportation Safety Board chairman Christopher Hart, told reporters. He faulted poor communication and said there was no indication of intentional wrongdoing.

Within hours after the release of the report, Boeing announced that CEO Dennis Muilenburg would lose his title as chairman of the aircraft maker. The move will allow Muilenburg to better focus on running the company, according to Boeing's board of directors, which named one their own, David L. Calhoun, to serve as non-executive chairman.

The Max has been grounded since March. The five-month international review was separate from the FAA's consideration of whether to recertify the plane once Boeing finishes updates to software and computers on the plane. Boeing hopes to win FAA approval before year end, although several previous Boeing forecasts have turned out to be wrong.

FAA Administrator Steve Dickson said in a prepared statement that the agency would review all recommendations from the panel and take appropriate action.

Boeing said it would work with the FAA to review the panel's recommendations and "continuously improve the process and approach used to validate and certify airplanes going forward."

The international panel included members from U.S. agencies, and aviation regulators from Europe, Canada, China and six other countries.

Hart, the chairman, said the U.S. aviation-safety system "has worked very well for decades" — he noted there has been just one accident-related death on a U.S. airliner in the past 10 years — "but this is a system that has room for improvement."

The panel's report is likely to increase questions around the FAA's use of aircraft manufacturers' own employees in the certification of parts and systems. The report found signs that Boeing put "undue pressures" on employees who worked on Max certification, "which further erodes the level of assurance" in the cooperative approach.

Congressional committees are already looking into the FAA's use of designated company employees. An FAA critic, Sen. Richard Blumenthal, D-Conn., called the report an indictment of "a failed, broken system of aviation safety scrutiny" that will add pressure to reform the program.

FAA officials have pointed to the safety record of American aviation as evidence that the program works. They add that it would require vast new staffing and cost billions for FAA employees to perform all necessary certification work. Hart said the FAA lacks the industry's technological expertise and has trouble hiring top engineers.

The report could also prompt a re-examination of automation, which experts say has led to erosion of flying skills among many pilots.

"As automation becomes more and more complex, pilots are less likely to fully understand it and more likely to have problems," Hart said. Most pilots can handle problems that occur in automated systems, he said, but "when some don't, that's a crash."

The panel said the FAA should use scientific studies to reconsider its assumptions about how quickly pilots can react to malfunctions.

Pilot unions, which criticized Boeing for not telling them about MCAS until after the first crash, praised the report.

"The first step toward ensuring this never happens again is recognizing where the failures were," said Dennis Tajer, a pilot for American Airlines and a spokesman for its pilot union. He said the findings should be incorporated into the FAA's current review of Boeing changes to the Max "because it will make a safer airplane and more highly trained pilots."

Jon Weaks, president of the pilot union at Southwest Airlines, said in a statement that the issues raised by the task force echo complaints by his union.

"As pilots, we have to be able to trust that Boeing will provide all the information we need to safely operate our aircraft," Weaks said. "In the case of the 737 Max, that absolutely did not happen."

Boeing expects FAA re-approval of the Max this year, and airlines would need one to two months more to resume flights. American, Southwest and United have all removed the Max from their schedules until January, after the Christmas travel rush.

Boeing is eager to resume delivering finished Max jets to customers. The company could be frustrated if regulators in other countries take longer than the FAA to review Boeing's changes to the plane.

Even if the FAA re-certifies the Max in December, "how much after that are the Europeans and the Chinese?" said Ken Herbert, an analyst who covers Boeing for Canaccord Genuity. "And what are the other potential issues that come out of those reviews? That's where the risk is."