Coast Guard: Transocean's poor safety culture contributed to Deepwater Horizon disaster

A swell partially obscures the Development Driller II, left, and Development Driller III, which drilled relief wells last summer at BP's Deepwater Horizon oil spill site in the Gulf of Mexico off the Louisiana coast.

NEW ORLEANS — Deepwater Horizon rig owner Transocean Ltd. had serious flaws in its safety management system and a poor safety culture that contributed to last year's deadly explosion that spawned the nation's worst offshore oil spill, according to a Coast Guard report released Friday.

The Coast Guard report also concludes that decisions made by workers aboard the rig "may have affected the explosions or their impact," such as failing to follow procedures for notifying other crew members about the emergency after the blast.

And in the years leading up to the disaster, Transocean had "serious safety management system failures and a poor safety culture," the report said.

"These deficiencies indicate that Transocean's failure to have an effective safety management system and instill a culture that emphasizes and ensures safety contributed to this disaster," the report said.

The report also found that lax oversight by the rig's flag state, the Republic of the Marshall Islands, was ineffective in preventing the disaster.

The April 20, 2010, explosion killed 11 workers and led to more than 200 million gallons of oil spewing from BP's Macondo well in the Gulf of Mexico.

A panel of officials from the Coast Guard and Bureau of Ocean Energy Management Regulation and Enforcement held a series of seven hearings for its probe of the Deepwater Horizon disaster. The bureau is expected to release its own preliminary report on the explosion before the two agencies issue a joint final report later this year.