Coincidental Pressures Led to Normal Human Heuristic and Error

1. Coincidental Pressures Led to Normal Human Heuristic and Error NPT Test Gauges TOO SIMILIAR to Riser Margin For Crew To Ignore

2. Pressure of Riser Mud Pushing “DOWN” is ~1,400 psi Pressure of Reservoir Pushing “UP” is ~1,400 psi

4. Coincidental Pressure Led to Normal Human Heuristic and Error • Bizarre Coincidence? OR • Mitigatable Confusion?

5. Coincidental Pressure Led to Normal Human Heuristic and Error • A quick check of the numbers available to the engineer that designed the NPT would have shown how close these numbers were to one another and known that this would confuse the crew into thinking the “closing pressure” on the Annular “Bag” preventer needed to be increased because the mud above the “Bag” created a “Differential” very close to 1,400 psi

6. Coincidental Pressure Led to Normal Human Heuristic and Error • Heuristic/hjʉˈrɪstɨk/; Greek: "Εὑρίσκω", "find" or "discover") refers to where the exhaustive search is impractical, heuristic methods are used to speed up the process of finding a satisfactory solution via mental shortcuts to ease the cognitive load of making a decision.

7. Coincidental Pressure Led to Normal Human Heuristic and Error • James Reason and other experts say the way to establish “Fault” is to use the “Substitution Test”. Basicly ask if any other worker in the same situation ‘might’ have come to the same conclusion. The answer is an emphatic, Yes! • Everyone on the rig came to exactly the same conclusion. The heuristic. The pressure was very close to the expected riser margin and thus the bladder effect WAS the heuristic.