On the fourth test flight, the KC-46 fly-by-wire boom extended out to its maximum range of 57 feet, 6 inches (18 meters). The fly-by-wire boom, based on the proven KC-10 boom, provides refueling capabilities to receiver aircraft such as the F-15, B-52, B-1, and C-17.

Boeing received a contract from the U.S. Air Force to build the next-generation aerial refueling tanker aircraft that will replace 179 of the service’s KC-135 tankers. The contract calls for Boeing to design, develop, manufacture and deliver 18 initial combat-ready KC-46A tankers by 2017.