A panel of international aviation regulators found that Boeing withheld key information about the 737 Max from pilots and regulators, and the Federal Aviation Administration lacked the expertise to understand an automated flight system implicated in two deadly crashes of Max jets.
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 FAA were not always told.
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.
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.
"We welcome this scrutiny and are confident that our openness to these efforts will further bolster aviation safety worldwide," Dickson said.
Boeing said it would work with 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 and eight foreign countries including Canada and China.
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 program of delegating some safety-related work to employees of the companies that it regulates.
The international panel found signs that Boeing put "undue pressures" on employees who worked on certification of the plane, "which further erodes the level of assurance" in the cooperative approach. Hart said he had no further details about the pressure.
Congressional committees are taking another look at the FAA policy of farming out much review work to designated employees of the manufacturers, whose work is supposed to be monitored by FAA inspectors.
FAA officials have pointed to the safety record of American aviation as evidence that the system is working. They add that it would require vast new staffing and cost billions for FAA to perform the work itself.
The FAA lacks industry's technological expertise and has trouble hiring leading-edge engineers. That hurts FAA's ability to analyze the safety of new technology.
"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."
Pilot unions, which have been critical of Boeing and the FAA for not disclosing the presence of new flight-control software in the Max, 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.
Tajer said it would be helpful if the report puts increased attention on FAA's review of changes that Boeing is now making to get the Max back in the sky.
"As for the Max, the more attention the better because it will make a safer airplane and more highly trained pilots, that's the good news," he said.
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 FAA to review Boeing's changes to the plane.
Even if 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."