Ms. Chao stressed that the F.A.A. sets of safety standards that manufacturers must meet while developing aircraft. The certification process, she said, "is, of course, subject to oversight and supervision by the FAA"
When asked by the subcommittee's chairwoman, Senator Susan Collins, Republican of Maine of the traveling public, "Ms. Chao said that the possibility was "troubling."
Mr. Elwell, during his hearing, said that the F.A.A. initially oversaw certification for the software, but delegated more authority over time, "when we had the comfort level" that the Boeing employees were knowledgeable enough about the system.
Boeing has defended the process, saying the plane adhered to all F.A.A. safety rules
A Boeing official cautioned against drawing any definite conclusions until more is known. "In general, the process has worked and continues to work, and we see no reason to overhaul the process," this official said, speaking on the condition of anonymity because of the investigations.
, many things go wrong. Based on what is known about the crashes in Indonesia and Ethiopia, Boeing said the field that MCAS was a need of updating.
robust, ”the official said.