The US Air Force has started the countdown to the KC-X contract award after having received three bids to build 179 tankers, including a last-minute offer from a California company selling Antonov aircraft. The contest is likely to remain a face-off between the Boeing KC-767NewGen Tanker and the EADS North America KC-45, even though Antonov-bidder US Aerospace touted a possibly lower $29.5 billion price tag for its proposal.