"Boeing's design and development of the 737 MAX was marred by technical design failures, lack of transparency with regulators and customers and efforts to obfuscate information about the operation of the aircraft," the report concludes. "During the development of the 737 MAX, Boeing engineers raised safety concerns about MCAS being tied to a single AOA sensor." Boeing has since agreed to have two sensors feed into MCAS and now recommends pilot simulator training on the 737 MAX before it returns to service. But Boeing's reactions to safety concerns "have consistently been too late," the report concludes.