HOUSTON (Reuters) - A cascade of human and mechanical failures likely caused last month's deadly offshore rig explosion and an undersea oil gusher that could be the worst U.S. environmental disaster, according to data gathered by congressional investigators and reviewed by experts.
Around 10:53 p.m. ET on April 20, Swiss-based Transocean Ltd's Deepwater Horizon rig exploded while it was drilling a well a mile beneath the Gulf of Mexico under contract for London-based BP Plc. Eleven rig workers are presumed dead.
