Regarding FD interruptions...don't your SOPs require a return to the beginning of the task underway if an interruption occurs? (Most SOPs do) Interruptions during a busy operation are a fact of life now and need to be seriously considered by a crew wanting to get away on time. Proper FD management is to simply remove the offending "interruptor" and finish that all important task, then invite the person or persons back in. Simple time management takes care of the risk of commiting a serious error like the one in question. In this case it seems like too many distractions, along with a poor decision regarding a rest period interruption (caused by implied pressure to operate?) allowed a simple error to be overlooked and compounded. Wasn't an improper rotation technique passed on by a training pilot mentioned in the intial findings as well? If all the above mentioned incidents are considered (SQ etc) the ability of a trained crew to recognise and correct such errors must be brought to question, not to assign blame, as some would like, but to correct the procedure(s) which lead to poor management. Additionally, in the MEL example, there were four qualified and experienced pilots on that FD...how did that error get missed? Proper management may have caught it, but somehow all four missed it. That's a mystery that hopefully is solved soon.