The Boeing [NYSE: BA] X-45A Unmanned Combat Air Vehicle, or UCAV, air vehicle 1 completed its sixth test flight December 19 at NASA's Dryden Flight Research Center, Edwards Air Force Base, Calif. The flight -- the first with the landing gear retracted and the first in which the vehicle took off and landed on a hard surface runway -- comes just over a month after the first flight of X-45A air vehicle 2 on November 21. After initial flight worthiness tests are completed, the flight test program will progress from single to multi-vehicle operations, including coordinated taxiing and flight, inter-vehicle communications, dropping inert ordnance and performing missions against simulated threats. The UCAV system is being developed by the Boeing Phantom Works advanced Research and Development unit and the Boeing Integrated Defense Systems business unit in partnership with the Defense Advanced Research Projects Agency and the U.S. Air Force. It is the first unmanned system designed from inception for combat, and the program is on track to provide the U.S. Air Force with initial operational capability by 2008.