[applied_heat]

You can really dumb it down to why didn’t you follow the checklist? If someone makes the same mistake after being corrected three times and the proper procedures exist for the worker to follow then the safety culture provides the structure and justification for their dismissal

[buildsjets]

No, you really need to smarten it up, and start off by making sure that your checklist is correct. Is it the correct checklist for the airplane model that you are building? Are all the right items on the checklist? Are they being done in the correct order? Do you have the correct validation/verification steps in your checklist? Does your checklist include all the parts that will need to be replaced? If the mechanic finds a quality issue while working the checklist and a job needs to be re-done, which checklists then need to be re-done? What other jobs are impacted by the rework?

All indications here (from the NTSB prelim and the widely reported whistleblower account) are that during rework for a minor manufacturing discrepancy, the mechanics on the shop floor followed bad manufacturing planning / engineering instructions to-the-letter, then the ball was dropped in error handling when the engineering instructions did not match the airplane configuration, because Boeing was using two different systems of record for error handling that did not communicate with each other except though manual coordination.

That's not the fault of the front-line assembly worker not following a checklist.

[applied_heat]

I agree with you. If the systems/procedures/checklists are bad it is not the fault of a front line worker.

I thought I was replying more to a parent comment addressing the inability to people go who repeatedly make mistakes, which is acceptable unless they are not following procedures.