The picture they painted suggested that the crew was lulled into routine just before the disaster. A key Transocean official was in the shower and apparently never heard early alarms. He had no thought of problems with the cement sealing the well, he said. "Everything was sorted out," said the official, Jimmy Harrell, the rig's offshore installation manager. The Deepwater Horizon rig was owned by Transocean Ltd.
Elsewhere on the rig that evening, the atmosphere was relaxed. Officials talked of the next well-drilling operation. A group of high-ranking BP officials were taking a tour and commended the crew on its safety record.
The gas surged up the well about 9:30 p.m. Some crew members apparently realized the well was out of control. But it was unclear what steps they took in this crucial period, which is the focus of elaborate training and preparation in the oil industry.
By the time Harrell made it to the control room and gave an order to activate an emergency system at 9:56 p.m., it was too late. Explosions had already rocked the rig, the power was out, flames had erupted and the control systems didn't respond.
BP investigators have suggested that the possible failure of contracted workers to properly monitor the well and to respond adequately once it blew contributed to the ensuing fire, and unleashed the catastrophic oil spill. Others have pointed to BP's engineering of the well.
Testimony before the Coast Guard committee suggested that the events aboard the Deepwater Horizon involved more than engineering choices.
Contradicting testimony from previous witnesses, Harrell denied that BP had tried to cut corners before the accident. He said there was no argument about pressure test results or potential leaks in the well before the blowout, as others have alleged.
Instead, Harrell said, he had discussions with BP officials about nitrogen used in cement. Harrell conceded that BP had at first not planned to conduct a "negative pressure test," a measure taken to check for leaks, on the day of the accident. But he said a BP official then reversed himself, agreed to do the test, then ordered it done a second time.
Although BP and independent experts have suggested these results were not read correctly, Harrell said there was no disagreement about the tests aboard the rig. "If I was aware of any problem, I would have been on the rig floor," he said.
A team of federal and academic experts assembled in the wake of misgivings about the official 5,000-barrel-a-day estimate of the leak flow has proved the doubters right. The independent panel's preliminary estimate, released Thursday, is that the 37-day-old leak has been spewing 12,000 to 19,000 barrels of oil a day into gulf waters. One part of that group pegged the upper limit at 25,000 barrels a day.
The more conservative range amounts to 18 million to nearly 29 million gallons of toxic crude oil that have bled into the gulf since the rig explosion damaged the wellhead. The grounded tanker in the Exxon Valdez accident spilled about 11 million gallons into Alaska's Prince William Sound.
Researchers from the University of South Florida said Thursday that they had detected what they believe is a six-mile-wide plume of oil below the surface, about 20 miles from the rig. The scientists said the column of dissolved hydrocarbons is at its thickest at a depth of two miles undersea, in a canyon lying deeper than the well.
After intense criticism from Louisiana officials for not moving more quickly, the U.S. Army Corps of Engineers on Thursday approved a permit for the state to build 45 miles of sand berms on a number of barrier islands in an effort to prevent oil from reaching more of the state's sensitive marshes and wetlands.
The agency approved only a small portion of the state's proposed dredging project, citing a host of environmental and practical reasons, including questions as to whether the unprecedented reconfiguring of the coast could even be accomplished in a reasonable time frame.
Meanwhile, two of seven boat crew members who had fallen ill after working on cleanup operations in Breton Sound remained hospitalized. Health, safety and environmental agencies are investigating. The men, 19 to 50 years old, suffered severe headaches, dizziness, nausea and skin irritation.
An emergency room doctor was unable to say what caused the sickness, but a hospital spokesman said the men had come in contact with a chemical-based irritant.
Times staff writers Julie Cart and Jill Leovy in Los Angeles, Louis Sahagun in Louisiana, Richard Simon in Washington, and Christi Parsons and Peter Nicholas of the Washington bureau contributed to this report.