WASHINGTON - A leading US senator blamed "a cascade of failures" Tuesday for a disastrous Gulf of Mexico oil spill and likened the crisis to the sinking of the Titanic and space shuttle Challenger explosion.
Democratic Senator Jeff Bingaman, leading the US Congress' first hearing into the catastrophe, also warned against "snap judgments" like ceasing all offshore drilling or shrugging off the crisis and pursuing business as usual.
"If this is like other catastrophic failures of technological systems in modern history -- whether it was the sinking of the Titanic, Three Mile Island, or the loss of the Challenger -- we will likely discover that there was a cascade of failures: Technical, human, and regulatory," he said.
The top Republican on Bingaman's Senate Energy and Natural Resources committee, Senator Lisa Murkowski, warned drilling "will never be without risk" but that industry and regulators "must never grow complacent" about safety.
The panel was to grill top executives from British energy giant BP, which leased the Deepwater Horizon offshore drilling platform and was majority owner of the well; Transocean, the rig's owner; and oil services firm Halliburton that did key technical work.
Moments before the hearing began, two groups of demonstrators took aim at BP, some with black teardrops painted on their faces in quiet protest, another calling out "BP kills wildlife, BP kills people, BP kills the planet."
Lawmakers were looking at technological and human failures that led to the April 20 blast that ultimately sent the rig to the bottom of the Gulf and millions of gallons (liters) gushing into its waters.
F. E. Beck, a professor of petroleum engineering, said it appeared barriers designed to control a "kick" -- when explosive natural gas enters the wellbore -- had failed, ultimately causing a "blowout" when gas flowed uncontrollably to the surface and ignited.
Beck played down concerns that the deepwater well might have tested the outer limits of the oil industry's abilities, saying it was "a very difficult well" but "not the most difficult well the industry has drilled by any means."
Elmer Danenberger, a former government regulator of offshore drilling, agreed with one senator that the disaster resulted from "a failure of systems."
Republican Senator John Barrasso scolded the executives for the "don't blame me" message of their prepared testimony, saying "shifting the blame does not get us very far" towards learning the lessons needed to prevent a repeat.
BP's top US executive, Lamar McKay, assured the committee in his written remarks that a 40-person team from his firm was investigating the disaster but "has not yet reached conclusions."
But the executive pointedly directed questions at the rig owner, saying Transocean Limited was responsible for a key piece of equipment that failed to prevent the explosion, and made it impossible to regain control of the well.
"The systems are intended to fail-closed and be fail-safe; sadly and for reasons we do not yet understand, in this case, they were not. Transocean?s blowout preventer failed to operate," he said.
Transocean chief Steven Newman, in his prepared remarks, said blaming the 450-ton blowout preventer "simply makes no sense" and stressed "all offshore oil and gas production projects begin and end with the operator," BP.
Newman also pointed the finger at Halliburton, saying the oil services company was responsible for the well's cement casing, a temporary cement plug in the top of the well, all meant to serve as barriers to a blowout.
"The one thing we know with certainty," he said, is that "there was a sudden, catastrophic failure of the cement, the casing, or both."
"Therein lies the root cause of this occurrence; without a disastrous failure of one of those elements, the explosion could not have occurred," Newman said.
But Halliburton's chief health, safety, and environment officer, Tim Probert, said in his prepared testimony that his company had finished its cementing work 20 hours before the blast and according to industry practice.
And Probert said Halliburton had never set the final cement plug because the catastrophe occurred as Transocean was doing work on the well.
AFP obtained copies of the prepared testimony on the eve of the hearing, the first of several into the disaster.
While oil companies are responsible for footing the entire cleanup bill, US lawmakers from coastal states have called for lifting the cap on their liability for economic damages from 75 million dollars to 10 billion dollars.
The undersea well has been spewing an estimated 210,000 gallons per day into the Gulf of Mexico since the rig sank April 22, after the blast that killed 11 workers.