Aegis Combat System The Aegis Combat System is an integrated naval weapons system developed by the Missile and Surface Radar Division of RCA , and now produced by Lockheed Martin . It uses powerful computers and radars to track and guide weapons to destroy enemy targets . Initially used by the United States Navy , Aegis is now used also by the Japan Maritime Self - Defense Force , Spanish Navy , Royal Norwegian Navy , and Republic of Korea Navy . Over 100 Aegis - equipped ships have been deployed in five navies worldwide . The Royal Australian Navy has selected the Aegis system for placement on its new Air Warfare Destroyers , and its part of NATO ' s European missile defence system . Etymology . The word " Aegis " is a reference that dates back to Greek mythology , with connotations of a protective shield , as the Aegis was the buckler ( shield ) of Athena . Overview . The Aegis Combat System ( ACS ) is an advanced command and control ( command and decision , or C & D , in Aegis parlance ) , and weapon control system ( WCS ) that uses powerful computers and radars to track and guide weapons to destroy enemy targets . The ACS is composed of the Aegis Weapon System ( AWS ) , the fast - reaction component of the Aegis Anti - Aircraft Warfare ( AAW ) capability , along with the Phalanx Close In Weapon System ( CIWS ) , the Mark 41 Vertical Launch System . Mk 41 VLS adopts a modular design concept , which result in different versions that vary in size and weight . The length comes in three sizes : for the self - defense version , for the tactical version , and for the strike version . The empty weight for a 8 - cell module is for the self - defense version , for the tactical version , and for the strike version , thus incorporating anti - submarine warfare ( ASW ) systems , and Tomahawk Land Attack Cruise Missiles ( TLAM ) . Shipboard torpedo and naval gunnery systems are also integrated . AWS , the heart of Aegis , comprises the AN / SPY - 1 Radar , MK 99 Fire Control System , WCS , the Command and Decision Suite , and SM - 2 Standard Missile family of weapons ; these include the basic RIM - 66 Standard , the RIM - 67 extended range missile , and the newer RIM - 161 designed to counter ballistic missile threats . A further SM - 2 based weapon , the RIM - 174 Standard ERAM is currently in testing , and may be integrated into the system in the near future . Individual ships may not carry all variants ; weapons load - outs are adjusted to suit assigned mission profile . The Aegis Combat System is controlled by an advanced , automatic detect - and - track , multi - function three - dimensional passive electronically scanned array radar , the AN / SPY - 1 . Known as " the Shield of the Fleet " , the SPY high - powered ( 6 megawatt ) radar is able to perform search , tracking , and missile guidance functions simultaneously with a track capacity of well over 100 targets at more than . However the AN / SPY - 1 Radar is mounted lower than the AN / SPS - 49 radar system and so has a reduced radar horizon . The Aegis system communicates with the Standard missiles through a radio frequency ( RF ) uplink using the AN / SPY - 1 radar for mid - course guidance of the missile during engagements , but still requires the AN / SPG - 62 radar for terminal guidance . This means that with proper scheduling of intercepts , a large number of targets can be engaged simultaneously . The computer - based command - and - decision element is the core of the Aegis Combat System . This interface makes the ACS capable of simultaneous operation against almost all kinds of threats . The Aegis Ballistic Missile Defense System program is intended to enable the Aegis system to act in a sea - based ballistic missile defense function , to counter short - and medium - range ballistic missile s of the variety typically employed by a number of potential opponent states . Development . Aegis was initially developed by the Missile and Surface Radar Division of RCA , which was then acquired by General Electric . The division responsible for the Aegis systems became Government Electronic Systems . This , and other GE Aerospace businesses , were sold to Martin Marietta in 1992 . This became part of Lockheed Martin in 1995 . By the late 1950s , the U . S . Navy replaced guns with guided missiles on its ships . These were sufficient weapons but by the late 1960s , the U . S . Navy recognized that reaction time , firepower , and operational availability in all environments did not match the anti - ship missile threat . The new threat of Soviet anti - ship missiles exposed a weakness in contemporary naval radar . The requirements of both tracking and targeting these missiles was limited by the number of radars on each ship , which was typically 2 - 4 . In 1958 the navy started the Typhon Combat System , a prophetic program culminated in the futuristic , but unreliable AN / SPG - 59 phased array radar which was never made viable and was canceled in 1963 to be replaced by the Advanced Surface Missile System ( ASMS ) . As a result , the US Navy decided to develop a program to defend ships from anti - ship missile threats . An Advanced Surface Missile System ( ASMS ) was promulgated and an engineering development program was initiated in 1964 to meet the requirements . ASMS was renamed " Aegis " in December 1969 after the aegis , the shield of the Greek god Zeus . The name was invented at the suggestion of Captain L . J . Stecher , a former Tartar Weapon System manager , after an internal U . S . Navy contest to name the ASMS program was initiated . Captain Stecher also submitted a possible acronym of Advanced Electronic Guided Interceptor System although this definition was never used . The main manufacturer of the Aegis Combat System , Lockheed Martin , makes no mention of the name Aegis being an acronym , nor does the U . S . Navy . Because the Aegis Combat System is the key component of several cruiser and destroyer class vessels , the ships are often incorrectly referred to as " Aegis class cruisers " or " Aegis class destroyers " . In reality , the radar system and the class of ship it is installed on are unrelated to each other . The first Engineering Development Model ( EDM - 1 ) was installed in a test ship , the USS " Norton Sound " , in 1973 . During this time frame , the Navy envisioned installing the Aegis Combat System on both a nuclear - powered " Strike Cruiser " ( or CSGN ) and a conventionally powered destroyer ( originally designated DDG 47 ) . The CSGN was to be a new , 17 , 200 ton cruiser design based on the earlier California - and Virginia - class cruisers . The Aegis destroyer design would be based on the gas turbine powered Spruance class . When the CSGN was cancelled , the Navy proposed a modified Virginia class design ( CGN 42 ) with a new superstructure designed for the Aegis Combat System and with a displacement of 12 , 100 tons . As compared to the CSGN , this design was not as survivable and had reduced command and control facilities for an embarked flag officer . Ultimately this design was also cancelled during the Carter Administration due to its increased cost compared to the non - nuclear DDG 47 . With the cancellation of the CGN 42 , the DDG 47 Aegis destroyer was redesignated as CG 47 , a guided missile cruiser . The first cruiser of this class was the " Ticonderoga " , which used two twin - armed Mark - 26 missile launchers , fore and aft . The commissioning of the sixth ship of the class , the " Bunker Hill " opened a new era in surface warfare as the first Aegis ship outfitted with the Martin Marietta Mark - 41 Vertical Launching System ( VLS ) , allowing a wider missile selection , more firepower , and survivability . The improved AN / SPY - 1B radar went to sea in the " Princeton " , ushering in another advance in Aegis capabilities . The " Chosin " introduced the AN / UYK - 43 / 44 computers , which provide increased processing capabilities . During 1980 , a destroyer was designed using an improved sea - keeping hull form , reduced infrared and radar cross - sections , and upgrades to the Aegis Combat System . The first ship of the " Arleigh Burke " class , the USS " Arleigh Burke " , was commissioned during 1991 . Flight II of the " Arleigh Burke " class , introduced in 1992 , incorporated improvements to the SPY radar , and to the Standard missile , active electronic countermeasures , and communications . Flight IIA , introduced in 2000 , added a helicopter hangar with one anti - submarine helicopter and one armed attack helicopter . The Aegis program has also projected reducing the cost of each Flight IIA ship by at least $ 30 million . Aegis Open Architecture . The Multi - Mission Signal Processor ( MMSP ) provides Anti - Air Warfare ( AAW ) / Ballistic Missile Defense ( BMD ) multi - mission capability for the first 28 ships ( DDG 51 - 78 ) of the US Navy ' s Arleigh Burke class destroyer as part of the Aegis Modernization Program . This capability will also be incorporated in the USS John Finn ( DDG - 113 ) and following new construction , and as well as Aegis Ashore . MMSP modifies transmitters of the SPY - 1D radar to enable dual - beam operation for reduced frame times and better reaction time , and provides stability for all D ( V ) waveforms . The SPY - 1 radar system detects , tracks , and supports engagements of a broader range of threats . MMSP improves performance in littoral , ducted clutter environments , and in electronic attack ( EA ) , and chaff environments and provides greater commonality in computer programs and equipment . This will result in the merger with Aegis Ballistic Missile Defense System . Technical development and issues . There are some reports that Aegis radar systems on board some individual warships are not being maintained properly . A Navy panel headed by retired Vice Adm . Phillip Balisle has issued the " Balisle report , " which asserts that over - emphasis on saving money , including cuts in crews and streamlined training and maintenance , has led to a drastic decline in readiness , and has left Aegis Combat Systems in low state of readiness . The biggest current blind spot for the ACS is underwater . Given the proliferation of ever more stealthy submarines this has become an issue of great concern for the US Navy . Iran Air Flight 655 . The Aegis system was involved in a disaster in which USS " Vincennes " shot down Iran Air Flight 655 during 1988 resulting in 290 civilian deaths . It was determined by a formal military investigation that the Aegis system was completely operational and did not have any maintenance problems . The investigation ruled that if the commanding officer had relied on the complete tactical data displayed by the Aegis system the engagement might never have occurred . Additionally , psychological effects of the crew subconsciously manipulating the data to accord with a predefined scenario greatly contributed to the false identification . The investigation found that the Aegis Combat System did not contribute to the incident , but did aid in the investigation by means of recorded target data . The discrepancies are as follows :