Airborne laser (ABL)

The ABL weapon system consists of a high-energy, chemical oxygen iodine laser (COIL) mounted on a modified 747-400F (freighter) aircraft to shoot down theater ballistic missiles in their boost phase. A crew of four, including pilot and copilot, would be required to operate the airborne laser, which would patrol in pairs at high altitude, about 40,000 feet, flying in orbits over friendly territory, scanning the horizon for the plumes of rising missiles. Capable of autonomous operation, the ABL would acquire and track missiles in the boost phase of flight, illuminating the missile with a tracking laser beam while computers measure the distance and calculate its course and direction. After acquiring and locking onto the target, a second laser - with weapons-class strength - would fire a three- to five-second burst from a turret located in the 747's nose, destroying the missiles over the launch area.