A US House report into two fatal crashes on Boeing 737 MAX planes has highlighted the Federal Aviation Administration's approval of the plane and Boeing's design failures, saying the flights were "doomed".
Boeing's 737 MAX planes have been grounded worldwide for nearly a year following the two crashes, that together killed 346 people.
The preliminary investigative findings from the US House Transportation Committee called the FAA's certification review of the 737 MAX "grossly insufficient" and said the agency had failed in its duty to identify key safety problems.
"The combination of these problems doomed the Lion Air and Ethiopian Airlines flights," the panel said in the 13-page report.
It also said Boeing's 737 MAX design "was marred by technical design failures, lack of transparency with both regulators and customers, and efforts to obfuscate information about the operation of the aircraft.
The report, which comes days ahead of the anniversary of the Ethiopian Airlines crash in March 2019 adds that the findings should prompt legislative changes to address how US regulators approve new aircraft for service.
The FAA said in a statement it welcomed the report's observations and said lessons learned from the two fatal crashes "will be a springboard to an even greater level of safety."
"While the FAA's certification processes are well-established and have consistently produced safe aircraft designs, we are a learning agency and welcome the scrutiny," the FAA said.
A draft interim report from Ethiopian crash investigators concludes the March 2019 crash of a Boeing 737 MAX was caused by the plane's design, according to sources.
A final report into the Lion Air crash released last October by Indonesia faulted Boeing's design of cockpit software on the 737 MAX but also cited errors by the airline's workers and crew.
The committee also concluded the FAA and Boeing missed "multiple red flags and clear data points" in recommending that the 737 MAX should continue to fly after the first crash, in October 2018.
Those decisions "gambled with the public's safety," it said.
Boeing is facing around 100 lawsuits from families of victims of the Ethiopian crash who have questioned why the US-based planemaker and authorities did not ground the MAX after the Lion Air crash.