Active deficiencies and defects developed by the operating team onboard the Deepwater Horizon activated the defects embedded in the system enabling penetration of the multiple barriers. A prime instance are the significant distractions and diversions of attention that developed during the multiple ongoing operations that were being performed during temporary abandonment operations that prevented accurate monitoring of drilling fluid flow into and out of the mud pits and prevented detecting subtle tendencies in well pressures and flows (weak signals in a strong noise environment). Another example was the confusion and uncertainty in the offshore teams’ thinking caused by the sequence of multiple last-minute (last-days) changes in BP’s plans and personnel used for preparation of the well’s future production and temporary abandonment.