The Deep Water Horizon oil rig burns in the Gulf of Mexico following a massive explosion in this photo taken in April of this year. A panel concluded that BP and its contractors ignored warning signs that the rig was not safe.

AP photo

BP and its contractors missed and ignored warning signs before the massive oil well blowout in the Gulf of Mexico, showing an "insufficient consideration of risk" and raising questions about the know-how of key personnel, a group of technical experts led by a University of Michigan professor concluded.

In a 28-page report released late Tuesday night, an independent panel convened by the National Academy of Engineering said that the companies failed to learn from "near misses" and that neither BP, its contractors nor federal regulators caught or corrected flawed decisions that contributed to the blowout.

Those failures would be unacceptable in companies that work with nuclear power or aviation, said Donald Winter, a professor of engineering practice at the University of Michigan and chairman of the 15-member study committee.

"A great number of decisions, all of which appear to us to be questionable ... also appeared to be justified by those individuals and those companies involved," Winter said Wednesday in an interview with The Associated Press. "In an operation like this you have to recognize the uncertainties of where you are going."

BP, and its contractors, apparently did not have such recognition, Winter said, even though drilling an exploratory well more than three miles beneath the ocean's surface involves significant unknowns, such as the underlying geology.

Among the hazards highlighted in the panel's report were several tests that indicated the cement at the bottom of the hole would not be an effective barrier to an influx of oil and gas. More than one month before the disaster, BP also lost drilling materials deep in the hole — a situation that hinted to the challenges of the well but was not used to address risks.

The report's technical findings — the second from an independent entity — mirror those discovered in previous investigations by BP, lawmakers and the president's oil spill commission. However, the panel focused more than other probes on how decisions were made.

Still, the report said it may not be possible to ever establish exactly what happened because much of the evidence was lost when 11 workers died and the rig sunk in April.

Interior Secretary Ken Salazar asked in May for the investigation by the academy, saying he wanted "an independent, science-based understanding of what happened."

In a statement issued Wednesday, Salazar and Bureau of Ocean Energy Management director Michael Bromwich said the committee's work will help guide the department to strengthen standards and oversight of offshore oil and gas recommendations.

A final report is due June 2011.