ST. LOUIS, Mo. - The Pentagon awarded a $35 billion Air Force refueling tanker contract to Northrop Grumman and the parent company of Airbus even though the Air Force's own evaluators found the Boeing Co.'s proposed aerial refueling tanker superior in at least two key areas, Boeing officials said Thursday.

A review of Pentagon files by The Boeing Co. revealed that Air Force evaluators found the Boeing KC-767 advanced tanker offered more mission capability and a better chance of surviving combat than the larger KC-30 tanker proposed by Northrop and the European Aeronautic Defence and Space Co.

The two aerospace firms were competing for the aerial tanker contract, which ultimately could be worth up to $100 billion over the coming years.

The Air Force's review also found that the Boeing's entry in the tanker competition had more strengths and fewer weaknesses overall than the Northrop-EADS tanker, Boeing officials found as part of their review.

“The fact that the Air Force gave Boeing the highest possible rating in mission capability and cited the KC-767 advanced tanker as having three times more strengths than the Northrop-EADS tanker in this most important category further highlights the inconsistencies in the selection process,” said Mark McGraw, vice president and program manager for Boeing Tanker Programs.

“As for protecting flight crews on the most dangerous missions, the Air Force evaluated Boeing’s tanker as much more survivable than the Northrop-EADS tanker.”

The Air Force selected Northrop-EADS' Airbus A330 derivative over Boeing’s KC-767 on Feb. 29. On March 11, The Boeing Co. asked the Government Accountability Office to review the decision, citing numerous irregularities and a flawed process that included making unstated changes to the bid requirements during the competition.

“Despite the changes made in favor of the KC-30 in the area of mission capability, the evaluation was clear in its assessment,” McGraw said. “The Air Force identified 98 strengths and only one weakness with the KC-767, while they pinpointed 30 strengths and five weaknesses for the KC-30, including four weaknesses in aerial refueling.”

The Air Force evaluation gave Boeing high marks in aerial refueling. Evaluators cited the ability of the KC-767 to refuel the V-22 Osprey, which the KC-30 was evaluated as not being able to do.

Air Force evaluators also cited the KC-767’s better maneuverability while flying heavily loaded into a refueling zone, and they said its refueling flight deck displays and communications systems were better than the KC-30's. Evaluators also found three weaknesses in Northrop-EADS’ boom design and an additional weakness in their ability to be a receiver due to the lighting of their receptacle.

In contrast, the Air Force said the KC-767 met or exceeded all key performance parameters in the mission capability requirements evaluation. Among some of the other key strengths: aeromedical evacuation, enhanced navigation system, better use of airport ramp space, better cockpit displays and communications systems, and more likely to integrate into operational use faster with new equipment and future growth.

“Also of significant concern for us is the fact that the Air Force settled for a plane that is ultimately less survivable for flight crews performing their vital missions in war zones,” McGraw said. “In providing technology and features that can keep the airplane more survivable for the men and women flying them, the Air Force determined that the KC-30 is less survivable than the KC-767.”

The Air Force found that in the critical area of combat survivability, the Boeing tanker had nearly five times as many strengths as Northrop’s. The Air Force said Boeing’s strengths totaled 24 and gave just five for Northrop-EADS.

The GAO has denied motions filed by Northrop Grumman Corp. and the Air Force to toss key portions of Boeing's protest of a $35 billion aerial tanker contract, Northrop Grumman said late Wednesday.

The contract to build 179 aerial refueling tankers is the first of three Air Force contracts worth as much as $100 billion over 30 years to replace its fleet of nearly 600 tankers.