Boeing and Northrop Grumman last week submitted rival bids for the US Air Force's KC-X tanker replacement programme. The difference in size between the two candidates is likely to be a major factor in the competition for a 179-aircraft contract expected to be worth up to $40 billion over 15 years.

Boeing says its KC-767 is "right-sized" for the primary air-refuelling mission, enabling access to 1,000 more bases than the KC-135 it would replace, but with the flexibility to carry 19 cargo pallets or 190 passengers. Northrop says its larger Airbus A330-200-based KC-30 "meets or exceedsevery key performance parameter far better than any competitor".

Boeing's design is based on the new 767-200 Long Range Freighter variant, for which KC-X would be the launch customer, says Mark McGraw, vice-president tanker programmes. Modifications for the tanker mission are likely to include improving the 767's field performance. "The USAF wants to operate off NATO-standard 8,000ft [2,450m] runways, and would prefer closer to 7,000ft," he says.

Under Northrop's proposal, A330 components would be produced by Airbus and delivered to EADS North America in Mobile, Alabama for assembly. The green aircraft would then be rolled across the airfield to Northrop's facility for installation of refuelling systems and military equipment.

Boeing plans to assemble its aircraft, with all military features, on the existing 767 line in Everett, Washington then deliver them to a finishing centre in Wichita, Kansas for installation of the military equipment. "There will be no structural modifications in Wichita," says McGraw.

A key element of the competition will be how much credit the USAF gives for exceeding its threshold requirements. "They will give credit if you can prove it is of value to the customer," says McGraw.

Source: Flight International