The preliminary findings were presented by the U.S. Chemical Safety and Hazard Investigation Board, a panel that often probes industry accidents but does not have regulatory authority.

The panel listed a litany of problems large and small they had already uncovered even though it has not received all of the records from Transocean, the drilling contractor that has challenged the board's right to investigate the offshore incident.

Among the panel's findings:

— BP and Transocean's "bridging document," designed to align safety procedures between the companies, was generic and addressed only six safety issues, but none of them dealt with major issues.

— The companies didn't have key process limits or controls for safe drilling.

— There were no written instructions for how to conduct a crucial test at the end of the cementing process, one that ultimately was misinterpreted by the crew after it was conducted several times, each time differently.

— Similar concerns about too narrow a focus on personal safety were raised after an explosion in 2005 at BP's Texas City refinery that killed 15 people, but few of the panel's recommendations were implemented on the offshore rig.

"It's always puzzled me why a company like BP ... that has major resources available ... is involved with two of the biggest accidents," said John Bresland, a member of the board who is wrapping up his second five-year term and was involved in both investigations.