I'd like to give you a little more detail on how the Integrated Fleet Aerial Refueling Assessment (IFARA) works.

The IFARA program models tanker refueling needs in four different scenarios.  Each of the four scenarios assumes a hypothetical future in which the U.S. is engaged on two different continents and needs to send tankers and drag (thus the affectionate term, "fighter drag") aircraft to those theaters while simultaneously maintaining a rigorous homeland defense. On a peak demand day in the simulation, there are hundreds of refueling events per day, per theater.

The procurement officials in charge of running the IFARA computer model are looking for what is known as "tail count" - the number of tanker aircraft required to complete 100% of the refueling missions in each scenario. To that end, they enter the capabilities and specifications of each tanker, which is paired with the number and location of bases, the strength of the pavement and the length of runways to determine the location and availability of tanker aircraft to complete the refueling missions.

The computer model then calculates an initial "tail count" for each tanker as well as additional information about what is required to accomplish the mission.

However, that's not the end of the story. The operator must then analyze the output of the computer model to determine if he or she can make it more efficient by transferring tankers from one base to another or changing a number of other variables. This requires a great deal of experience with tanker missions and resource allocation.

Then the operator inputs this more efficient information into the computer model and runs it again. They repeat this process until the tail count cannot be further reduced.

In the last step, the procurement officials calculate the Fleet Effectiveness Value (FEV) by dividing the number of KC-135 tanker aircraft needed to successfully complete all the missions in each scenario by the number of KC-X tankers needed to complete the same mission. The FEV is the bottom-line measure of each tanker's capabilities compared to today's tankers, and is one of the most important metrics in the entire competition. It is worth potentially billions of dollars.

The complexity of the IFARA computer model should give you some idea of why we feel it is so important to facilitate transparent communication between the competitors and the Air Force. We believe that Boeing has developed state-of-the-art tankers that are the best in the world - we are now working to understand the evaluation criteria to the best of our ability so we propose the best tanker for the U.S. warfighter.