Even if they didn't know about the MCAS, they still knew the plane had had an uncontrolled-dive problem from an unknown cause. How is it responsible to fly it without understanding the issue?
Boeing is still fully culpable, but the airline should have debugged the issue before using the plane again.
> How is it responsible to fly it without understanding the issue?
There is not only "the issue" there are a lot of "issues" happening all the time. The problem is even knowing which are "too serious." That the single faulty sensor which didn't affect anything on the previous planes could mean the difference between the life and death was specifically not reported by Boeing.
How it is responsible to certify the plane without properly analyzing the MCAS implementation?
> That the single faulty sensor which didn't affect anything on the previous planes could mean the difference between the life and death was specifically not reported by Boeing.
We're not talking about a faulty sensor, we're talking about an uncontrolled dive. The airline is not at fault for not connecting the two, but that only means they had information of an uncontrolled dive from an unknown cause, and still flew the plane.
> How it is responsible to certify the plane without properly analyzing the MCAS implementation? (...) And how it is responsible to claim "everything is OK everywhere" after the two crashes?
It's not, but that's whataboutism. Boeing's neglect doesn't excuse the FAA, and the FAA's neglect doesn't excuse the airline.
Boeing is still fully culpable, but the airline should have debugged the issue before using the plane again.