The Air Force on Friday launched its third attempt to award a $35 billion tanker contract to either Boeing Co. or Northrop Grumman Corp.

The Air Force said it will be "crystal clear" in its requirements for new tankers that refuel military planes in flight in order to avoid errors from previous selection processes. The service also now wants a plane that's war-ready on day one.

Los Angeles-based Northrop, and its partner Airbus parent European Aeronautic Defense and Space Co. N.V., are offering a tanker based on the Airbus A330. Northrop said it will review the draft request for bids and provide comments to the Air Force soon. Chicago-based Boeing said it will conduct a detailed review of the service's request to assess which plane it will offer -- the 767-based tanker, the larger 777-based tanker, or perhaps both.

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

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