The US Air Force has decided to issue the final terms for the bids to build the multibillion-dollar KC-X refuelling tankers after 23 February 2010.

On 8 February 2010, the air force said, in a pre-solicitation notice, that the acquisition would be a full and open, best-value competition, according to Reuters.

The air force said it plans to issue a fixed-price-type contract for the development of a new aerial refuelling tanker, including four developmental aircraft.

The contract will have options to produce 175 production planes, based on existing commercial designs, at a rate of about 15 planes a year.

The proposals are due 75 days from the date of the final request, and a winner will be chosen in the fourth quarter of fiscal 2010, which ends 30 September, said the notice.

In February 2008, Northrop and EADS won the $35bn contract to build the mid-air refuelling tankers for the USAF. The contract was, however, cancelled by the Pentagon, following a protest by losing bidder Boeing.