So what caused the Deepwater Horizon oil rig to fail? Here's the latest:
BP previously told investigators that a "negative pressure" test, which checks for leaks in the well, was inconclusive at best and "not satisfactory" at worst. But in the meeting Tuesday, BP went further, saying the results were an "indicator of a very large abnormality" but that workers — unnamed in the memo — decided by 7:55 p.m. that the test was successful after all. That may have been a "fundamental mistake," BP's investigator said in the meeting, according to the memo.
Next up is a "top kill," in which mud is injected into the well in order to plug the broken pipe. According to one expert, "There's always a trade-off between making it better and making it worse. This probably has the least amount of risk of making it worse." Why does that not make me feel especially comforted?