This timeline accompanies BP's Bubbling Cauldron
April 16, 2010 Engineers express concerns about the concrete around the well, but those concerns are dismissed by BP because of cost.
April 20 The BP-licensed Transocean drilling rig Deepwater Horizon explodes and burns in the Gulf of Mexico. Eleven people are reported missing and approximately 17 are injured. A blowout preventer, intended to prevent release of crude oil, failed to activate.
April 22 The Deepwater Horizon rig sinks; reports surface of a five-mile-long oil slick. Search-and-rescue operations begin.
April 29 President Obama pledges "every single available resource" to contain the spill and says BP is responsible for the cleanup. Louisiana Gov. Bobby Jindal declares a state of emergency as the oil slick approaches land.
May 4 A closed congressional session is held with BP executives to determine cause, scope and fallout from the tragedy.
May 11 At a Senate hearing, representatives of BP, Halliburton and Transocean blame each other for the accident. Testifying above, from left, are Lamar McKay, president and chairman of BP American, and Elmer Danenberger, former chief of Offshore Regulatory Program Minerals Management Services.
May 30 CEO Tony Hayward causes outrage after telling reporters, "There's no one who wants this over more than I do. I would like my life back."
July 26 BP announces Hayward will leave, to be replaced by new CEO Robert Dudley. Seated at right are, from left, Hayward and Dudley.
Aug. 15 It is revealed that BP has yet to update its oil-spill emergency plan more than three months after the Deepwater Horizon rig exploded. (Documented errors include the identification of the sea walrus as an animal in need of protection, despite there being none in the Gulf, and the listing of a wildlife expert who died four years before the plan was approved.)
Nov. 2 BP increases the estimated total cost of the oil spill to $40 billion, $7.7 billion more than previously expected.
Dec. 15 The United States files a suit for damages against BP and several of its partners.
Jan. 6, 2011 The National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling concludes that the oil spill in the Gulf of Mexico was the result of systematic management failure at BP, Transocean and Halliburton.