The Boeing YAL-1 Airborne Laser (ABL) weapons system is a megawatt-class chemical oxygen iodine laser (COIL) mounted inside a modified Boeing 747-400F. It is primarily designed to destroy tactical ballistic missiles (TBMs), similar to the Scud, while in boost phase. The low-power lasers have been test-fired in flight, aimed at an airborne target board. The aircraft was designated YAL-1A in 2004 by the U.S. Department of Defense. The Airborne Laser Laboratory, a less-powerful prototype installed in a Boeing NKC-135A, shot down several missiles in the 1980s.
The ABL does not burn through or disintegrate its target. It heats the missile skin, weakening it, causing failure from high speed flight stress. If proven successful, seven ABL-armed 747s will be built and assigned to two combat theaters. The aircraft were originally slated to enter service in 2008, but development has been slower and costlier than planned. The current plan calls for a prototype ABL to attempt to shoot down a test missile in 2009. Data acquired in the test will shape the final production design, which is now expected to enter service several years from now.
The ABL system uses infrared sensors for initial missile detection. After initial detection, three low power tracking lasers calculate missile course, speed, an aimpoint, and air turbulence. Air turbulence deflects and distorts the laser beam. The ABL adaptive optics use the turbulence measurement to compensate for atmospheric errors. The main laser, located in a turret on the aircraft nose, is fired for 3 to 5 seconds, causing the missile to break up in flight near the launch area. The ABL is not designed to intercept TBMs in the terminal, or descending, flight phase. Thus, the ABL must be within a few hundred kilometers of the missile launch point. All of this occurs in approximately 8 to 12 seconds.
Watch it in action. Watch the video below.