Two years after receiving the first production Standard Missile 6 (SM-6) anti-aircraft missile, the U.S. Navy successfully tested it hitting an aircraft (a BQM-74 target UAV) over the horizon. The SM-6 is basically the existing SM-2 anti-aircraft missile with the more capable guidance system of the AMRAAM air-to-air missile, as well as other improvements in the electronics and other components. The SM-6 is a 1.5 ton, 6.55 meter (21.5 foot) long, 533mm (21 inch) diameter missile. It has a max range of 240 kilometers and max altitude of 33 kilometers (110,000 feet).
The older SM-2 is 1.35 ton, 8 meter (26.2 foot) long missile with a max range of 190 kilometers and max altitude of 24.4 kilometers (80,200 feet). The main change for the SM-6 is the AMRAAM guidance system which is self-contained and will seek out any target it comes within range of. The SM-2 uses a "semi-active" guidance system, which requires that a special targeting radar "light up" the target with a radar beam, which the SM-2 guidance system detects and homes in on. The "active" guidance system of the SM-6 is thus harder to jam and can home in on targets beyond the range of targeting radars. The SM-6 can attack anti-ship missiles as well.
The SM-6 took 9 years to develop and is now in production, with the initial order for 1,200 missiles at a cost of $4.3 million each. SM-6 will replace many of the SM-2 missiles currently carried by American and Australian warships.
Meanwhile, the navy has been continuing years of improvements in the Aegis radar and fire control system that controls SM-2, SM-6, and the smaller SM-3 anti-missile version. The SM-3 can destroy ballistic missiles and low orbit satellites. Aegis equipped ships are now getting version 4.0 and the next major upgrade (5.0) will make the anti-missile capabilities a standard feature of Aegis software. New destroyers are having anti-missile Aegis software installed as standard equipment. Much of the anti-missile capability of the original Aegis anti-aircraft system came from upgrades to the Aegis software.
The Aegis anti-missile system has had a success rate of over 80 percent in knocking down incoming ballistic missile warheads during test firings. To achieve this, two similar models of the U.S. Navy Standard anti-aircraft missile are in service, in addition to a modified (to track incoming ballistic missiles version) version of the Aegis radar system.
The RIM-161A, also known as the Standard Missile 3 (or SM-3), has a range of over 500 kilometers and max altitude of over 160 kilometers. The Standard 3 is based on the anti-missile version of the Standard 2 (SM-2 Block IV). This SM-3 missile has a shorter range than the SM-2, which can destroy a warhead that is more than 200 kilometers up. The SM-3 is only good for anti-missile work, while the SM-2 Block IV can be used against both ballistic missiles and aircraft. The SM-2 Block IV also costs less than half of what an SM-3 costs.