The Airborne Laser missile defense system has begun flight tests with the entire weapon system integrated aboard the aircraft, The Boeing Co. [BA] announced.

Boeing, the prime ABL contractor, contributed the heavily modified 747-400F jumbo jet, in which Northrop Grumman Corp. [NOC] installed a laser system and Lockheed Martin Corp. [LMT] installed a beam control-fire control system.

The aircraft completed its functional flight check with those systems in place, confirming the giant plane is airworthy, ready for more airborne tests, and on track for its missile-intercept demonstration this year.

Ironically, while the ABL prototype aircraft is showing these signs of progress and is meeting its milestones, Secretary of Defense Robert Gates has proposed a Department of Defense budget plan for the fiscal year ending Sept. 30, 2010, that effectively would sideline the ABL program, barring any purchase of further planes in fiscal 2010 even if the ABL successfully takes down a missile in a test this year.

“With ABL’s return to flight, we are on the verge of fully demonstrating the unprecedented speed, mobility, precision and lethality that ABL could provide to America’s warfighters,” said Michael Rinn, Boeing vice president and ABL program director. Boeing also provides the ABL battle management system.

The missile defense system would deter potential adversaries and provide speed-of-light capability to destroy all classes of ballistic missiles in their boost phase of flight, just after liftoff from a launch pad or ground silo.

That would destroy the enemy missile before it has a chance to emit multiple warheads or confusing chaff. Eliminating missiles in their boost phase also would reduce the number of shots required by other elements of the layered ballistic missile defense system, in case the missile survived to enter the midcourse or terminal phases of its ballistic trajectory. ABL also has the potential to be employed for other missions, including destroying aircraft and surface-to-air missiles.

The ABL program has logged many accomplishments over the past several years. In 2007, ABL completed almost 50 flight tests that demonstrated its ability to track an airborne target, measure and compensate for atmospheric conditions, and deliver a surrogate high-energy laser beam on the target. Last year, the team completed installing the high-energy laser onboard the aircraft and, for the first time, operated the entire weapon system at high power levels.