Timeline: The tanker saga

The effort to replace the Air Force's Eisenhower-era fleet of more than 500 air-refueling tankers has been fraught with controversy from the start.

October 2001: As the airline industry struggles following the Sept. 11 terrorist attacks, the Air Force proposes to lease 100 air-refueling tankers from Boeing at a cost of $20 billion or more. Sen. John McCain quickly becomes the chief critic, calling it "a sweet deal" for Boeing that would cost taxpayers more than alternative plans.

November 2003: Boeing fires CFO Mike Sears and Vice President Darleen Druyun after concluding Sears improperly offered her a job while she was a top Air Force acquisitions officer overseeing the tanker contract. Boeing CEO Phil Condit resigns a week later. The following spring, Defense Secretary Donald Rumsfeld effectively scraps the tanker-leasing deal.

September 2005: Northrop Grumman officially teams up with EADS — European Aeronautic Defence & Space, the parent of European aircraft-maker Airbus — to bid for the first 179-plane contract.

2008

January: The Airbus chief says EADS will assemble commercial jets, as well as Air Force tankers in Mobile, Ala., if his team wins.

February: The Pentagon announces that Northrop-EADS will build its next generation of tankers, now named the KC-45A.

March: Boeing files a protest of the Air Force contract award. Company Chairman and CEO Jim McNerney calls it "an extraordinary step rarely taken by our company, and one we take very seriously."

June: The Government Accountability Office backs Boeing's protest, finding the Defense Department made at least seven major mistakes in the procurement process that detracted from "full and open competition and fairness." It says the Air Force should rebid the contract.

July 9: Defense Secretary Robert Gates says the Pentagon will rebid the tanker contract, and his office, not the Air Force, will choose the winner.

Aug. 6: Pentagon releases a draft request for bids to Boeing and Northrop-EADS.

Aug. 22: Boeing says it may bail out of the contest unless it gets additional time from the Pentagon to assemble its offer.

Sept. 10: The Defense Department delays the tanker competition, handing a victory to Boeing and leaving the politically charged decision for the next president.

2009

Sept. 25: The Air Force launches its third attempt to award the $35 billion tanker contract, shortly after Secretary Gates restores its authority to decide the winner.

Oct. 28: Northrop says the new request for proposals is biased toward Boeing because it prioritizes cost over expanded capabilities.

Dec. 1: Northrop Grumman warns it won't bid for the tanker contract unless the Pentagon's draft request for proposals is rewritten.