The Chemical Safety Board said gaps in programs for managing safety at offshore wells included a failure to assess the potential risks while drilling the Macondo well in the gulf, the Houston Chronicle reported Monday.
"BP and Transocean had multiple safety management system deficiencies that contributed to the Macondo incident," the board said in its report.
The board recommended federal regulators step up monitoring of offshore incidents that may serve as early warning signs of potentially catastrophic accidents.
The safety board investigation is the last major investigation into what went wrong when oil and explosive gas surged from of the Macondo well April 20, 2010, and ignited aboard the Deepwater Horizon rig, killing 11 workers and seriously injuring 17 others, as well letting loose an oil spill that lasted for months and dumped an estimated 4.9 million barrels of oil into the gulf.
Among other things, the report says Britain's BP didn't assess the potential accidents and risks while drilling the well 41 miles off Louisiana and a mile under the gulf surface.
Similarly, Swiss-based Transocean's safety assessment of the Deepwater Horizon rig in 2004 emphasized personal safety issues but didn't include recommendations to address major accident risks, the report said.
Safety consultant Kenneth Arnold said at the hearing the oil and gas industry needs to develop a "culture of safety," the Chronicle reported.
Chemical Safety Board investigators said BP has developed "a more rigorous process safety indicators program" since the 2010 disaster that can alert operators to potential trouble.
Transocean said in a statement it will review the board's report and is "committed to continuous improvement in both personal and process safety performance," the Chronicle said.