Pentagon relaunches contest for aerial refueling tanker contract

But what was once a sprint has become a marathon as the Pentagon attempts for a fourth time to replace its fleet of 415 Eisenhower-era tankers through contracts expected to total more than $100 billion.

The Air Force said it would be "crystal clear" in its requirements for new tankers to avoid errors from previous selection processes. The service also now wants a plane that's war-ready on Day One.

Century City-based Northrop and its partner European Aeronautic Defense and Space Co., parent of Airbus, are offering a tanker based on the Airbus A330.

Northrop said it would review the draft request for bids and provide comments to the Air Force soon.

Chicago-based Boeing said it would conduct a detailed review of the service's request to assess which plane it would offer -- the 767-based tanker, the larger 777-based tanker, or perhaps both.

The companies and lawmakers have 60 days to comment on the Air Force's proposal before a final version is released.