The Boeing YAL-1 Airborne Laser Testbed (formerly Airborne Laser) weapons system was a megawatt-class chemical oxygen iodine laser (COIL) mounted inside a modified Boeing 747-400F. It is primarily designed as a missile defense system to destroy tactical ballistic missiles (TBMs) while in boost phase. The aircraft was designated YAL-1A in 2004 by the U.S. Department of Defense.[1]