The Boeing-led Airborne Laser (ABL) team exposed the aircraft’s conformal window for the first time during flight, a maneuver necessary for the weapon system to complete its mission of shooting down an enemy ballistic missile during the boost phase of flight.

Missile Defense Agency Director Lt. Gen. Trey Obering, in a May 20 statement, announced the ABL 1.7-meter conformal window had been successfully exposed. The exposure test, the MDA statement said, is an “important part of the flight test series being conducted this year.”

Obering also recently told reporters that “the Airbone Laser has had some great successes” and the system continues to improve as the MDA’s “primary boost phase defense” system.

Boeing is prime contractor for the ABL system under contract to the MDA. The system consists of a megawatt-class, high-energy Chemical Oxygen Iodine Laser (COIL) installed on a Boeing 747-400F aircraft for the detection, tracking and destruction of ballistic missiles in the boost phase. ABL also can pass information on launch site, target track and predicted impact point to other layers of the global ballistic missile defense system.

The conformal window exposure occurred during the 18th flight in the current test series for the ABL YAL-1A aircraft. The window, which is shaped like a huge contact lens, took five years to manufacture and is one of the most complex optics ever developed. It is mounted in a rotating turret-ball assembly on the nose of the aircraft. During takeoff and landing, the window is rotated into the “stowed” position, where it is protected by a gasket and shield. During an operational mission, three of the four ABL lasers that propagate outside the aircraft, including the megawatt-class laser, are fired through the window. The conformal window is a significant technological feat with respect to manufacturing and high structural reliability for an airborne military weapon system, and still meets the superior optical qualities required to deliver the megawatt-class COIL laser energy on target, said Frank Dugger, the Boeing ABL Program structural engineer who was responsible for attaining flight clearance of the window.

“The long hours of work and restless sleep worrying about the window’s structural integrity was well worth the opportunity of seeing this successful one-of-a-kind window unstow and slew underneath the flight turret,” Dugger said. “This is truly a proud day to be a small part of the tremendous effort by all the contractor and customer members to advance the revolutionary ABL one more step toward reality.”

The Boeing ABL team and MDA in 2004 completed the system’s “first light” test, which involved firing a laser beam for the first time using the ABL flight laser modules at the ABL System Integration Lab at Edwards Air Force Base, Calif. The ABL aircraft last year also conducted its “first flight” to validate the airworthiness and functionality of the battle management and Beam Control/Fire Control (BC/FC) segments on board the platform.

Following the first-light and first-flight milestones, the ABL program moved into the next phase of testing, which is aimed at further validating the weapon system as a critical component of the United States’ multilayered defense against ballistic missiles. All of the ABL flight hardware has been delivered and is in various stages of integration, as the Boeing-led team moves toward an ultimate capability demonstration.

Boeing is the weapon system integrator for ABL and provides the modified aircraft and battle management segments. Other ABL partners include Northrop Grumman, which provides the laser segment, and Lockheed Martin, which provides the BC/FC segment.