AIM - 7 Sparrow The AIM - 7 Sparrow is an American , medium - range semi - active radar homing air - to - air missile operated by the United States Air Force , United States Navy and United States Marine Corps , as well as various allied air forces and navies . Sparrow and its derivatives were the West ' s principal beyond visual range ( BVR ) air - to - air missile from the late 1950s until the 1990s . It remains in service , although it is being phased out in aviation applications in favor of the more advanced AIM - 120 AMRAAM . The Self - Defence Forces of Japan also employ the Sparrow missile , though it is being phased out and replaced by the Mitsubishi AAM - 4 . NATO pilots use the brevity code Fox One in radio communication to signal launch of a Semi - Active Radar Homing Missile such as the Sparrow . The Sparrow was used as the basis for a surface - to - air missile , the RIM - 7 Sea Sparrow , which is used by the United States Navy for air defense of its ships . Development . Sparrow I . from a late - 1940s United States Navy program to develop a guided rocket weapon for air - to - air use . In 1947 the Navy contracted Sperry to build a beam riding version of a standard HVAR , the standard unguided aerial rocket , under Project Hotshot . The weapon was initially dubbed KAS - 1 , then AAM - 2 , and , from 1948 on , AAM - N - 2 . The airframe was developed by Douglas Aircraft Company . The diameter of the HVAR proved to be inadequate for the electronics , leading Douglas to expand the missile ' s airframe to diameter . The prototype weapon began unpowered flight - tests in 1947 , and made its first aerial interception in 1952 . After a protracted development cycle the initial AAM - N - 2 " Sparrow " entered limited operational service in 1954 with specially modified Skyknight s all weather carrier night fighters . And in 1956 , they were carried by the F3H - 2M Demon and F7U Cutlass fighter aircraft . Compared to the modern versions , the Sparrow I was more streamlined and featured a bullet - shaped airframe with a long pointed nose . Sparrow I was a limited and rather primitive weapon . The limitations of beam - riding guidance ( which was slaved to an optical sight on single seater fighters and a radar with night fighters ) restricted the missile to attacks against targets flying a straight course and made it essentially useless against a maneuvering target . Only about 2 , 000 rounds were produced to this standard . Sparrow II . As early as 1950 Douglas examined equipping the Sparrow with an active radar seeker , initially known as XAAM - N - 2a " Sparrow II , the original retroactively becoming Sparrow I " . In 1952 it was given the new code AAM - N - 3 . The active radar made the Sparrow II a " fire and forget " weapon , allowing several to be fired at separate targets at the same time . By 1955 Douglas proposed going ahead with development , intending it to be the primary weapon for the F5D Skylancer interceptor . It was later selected , with some controversy , to be the primary weapon for the Canadian Avro Arrow supersonic interceptor , along with the new Astra fire - control system . For Canadian use and as a second source for US missiles , Canadair was selected to build the missiles in Quebec . The small size of the missile forebody and the K - band AN / APQ - 64 - radar limited performance , and it was never able to work in testing . After considerable development and test firings in the U . S . and Canada , Douglas abandoned development in 1956 . Canadair continued development until the Arrow was cancelled in 1958 . Sparrow X . A subvariant of the Sparrow I armed with the same nuclear warhead as the MB - 1 Genie was proposed in 1958 , but was cancelled shortly thereafter . Sparrow III . Concurrently with the development of the Sparrow I , in 1951 , Raytheon began work on the semi - active radar homing version of Sparrow family of missiles , the AAM - N - 6 " Sparrow III " . The first of these weapons entered United States Navy service in 1958 . The AAM - N - 6a was similar to the - 6 , but used a new Thiokol liquid - fuel rocket engine for improved performance . It also included changes to the guidance electronics to make it effective at higher closing speeds . The - 6a was also selected to arm the Air Force ' s " F - 110A Spectre " ( F - 4 Phantom ) fighters in 1962 , known to them as the AIM - 101 . It entered production in 1959 , with 7500 being built . Another upgrade reverted to a Rocketdyne solid - fuel motor for the AAM - N - 6b , which started production in 1963 . The new motor significantly increased maximum range to for head - on attacks . During this year the Navy and Air Force agreed on standardized naming conventions for their missiles . The Sparrows became the AIM - 7 series . The original Sparrow I and aborted Sparrow II became the AIM - 7A and AIM - 7B , despite both being out of service . The - 6 , - 6a and - 6B became the AIM - 7C , AIM - 7D and AIM - 7E respectively . 25 , 000 AIM - 7Es were produced , and saw extensive use during the Vietnam War , where its performance was generally considered disappointing . The mixed results were a combination of reliability problems ( exacerbated by the tropical climate ) , limited pilot training in fighter - to - fighter combat , and restrictive rules of engagement that generally prohibited BVR ( beyond visual range ) engagements . The P ( kill probability ) of the AIM - 7E was less than 10 % ; US fighter pilots shot down 60 aircraft out of the 612 Sparrows fired . In 1969 an improved version , the E - 2 , was introduced with clipped wings and various changes to the fuzing . Considered a " dogfight Sparrow " , the AIM - 7E - 2 was intended to be used at shorter ranges where the missile was still travelling at high speeds , and in the head - on aspect , making it much more useful in the visual limitations imposed on the engagements . Even so , its kill rate was only 13 % in combat , leading to a practice of ripple - firing all four at once in hopes of increasing kill probability . Its worst tendency was that of detonating prematurely , approximately a thousand feet in front of the launching aircraft , but it also had many motor failures , erratic flights , and fuzing problems . An E - 3 version included additional changes to the fuzing , and an E - 4 featured a modified seeker for use with the F - 14 Tomcat . U . S . AIM - 7 Sparrow Aerial Combat Victories in the Vietnam War 1965 - 1973 . Improved versions of the AIM - 7 were developed in the 1970s in an attempt to address the weapon ' s limitations . The AIM - 7F , which entered service in 1976 , had a dual - stage rocket motor for longer range , solid - state electronics for greatly improved reliability , and a larger warhead . Even this version had room for improvement , leading British Aerospace and the Italian firm Alenia to develop advanced versions of Sparrow with better performance and improved electronics as the BAe Skyflash and Alenia Aspide , respectively . The most common version of the Sparrow today , the AIM - 7M , entered service in 1982 and featured a new inverse monopulse seeker ( matching the capabilities of Skyflash ) , active radar fuse , digital controls , improved ECM resistance , and better low - altitude performance . It was used to good advantage in the 1991 Gulf War , where it scored many USAF air - to - air kills ; its kill probability , overall , is still less than 40 % . The AIM - 7P is similar in most ways to the M versions , and was primarily an upgrade program for existing M - series missiles . The main changes were to the software , improving low - level performance . A follow - on Block II upgrade added a new rear receiver allowing the missile to receive mid - course correction from the launching aircraft . Plans initially called for all M versions to be upgraded , but currently P ' s are being issued as required to replace M ' s lost or removed from the inventory . The final version of the missile was to have been the AIM - 7R , which added an infrared seeker to an otherwise unchanged AIM - 7P Block II . A general wind - down of the budget led to it being cancelled in 1997 . Sparrow is now being phased out with the availability of the active - radar AIM - 120 AMRAAM , but is likely to remain in service for several years . Foreign versions . Canada . As part of the Avro Arrow program , Canadair partnered with Douglas in the development of the Sparrow II ( AIM - 7B ) . After Douglas dropped out of this program , Canadair continued on with it until the termination of the Arrow . Italy . The Italian company Finmeccanica , Alenia Difesa licensed the AIM - 7E Sparrow technology from the US , and produced its own improved version called Aspide . UK . British Aerospace ( BAe ) licensed the AIM - 7E2 technology in the 1970s , producing the Skyflash missile . Skyflash used a Marconi XJ521 monopulse Semi - Active seeker together with improvements to the electronics . It was powered by the Aerojet Mk52 mod 2 rocket engine ( later by the Rocketdyne Mk38 mod 4 ) . Skyflash entered service with the Royal Air Force ( RAF ) on their Phantom FG . 1 / FGR . 2 in 1976 , and later on the Tornado F3 . Skyflash was also exported to Sweden for use on their Viggen fighters . An upgraded version with active radar seeker , called Active Sky Flash was proposed by BAe and Thomson - CSF , but did not receive funding because the RAF opted for other missiles . People ' s Republic of China . The LY - 60 / FD - 60 / PL - 10 is a family of PRC missiles developed by the Shanghai Academy of Science and Technology , largely based on the Italian Aspide missile - a version of the Sparrow . There are four versions of the basic design , three of which are surface - to - air and one air - to - air . Design . The Sparrow has four major sections : guidance section , warhead , control , and rocket motor ( currently the Hercules MK - 58 solid - propellant rocket motor ) . It has a cylindrical body with four wings at mid - body and four tail fins . Although the external dimensions of the Sparrow remained relatively unchanged from model to model , the internal components of newer missiles represent major improvements , with vastly increased capabilities . The warhead is of the continuous - rod type . As with other semi - active radar guided missiles , the missile does not generate radar signals , but instead homes in on reflected continuous - wave signals from the launch platform ' s radar . The receiver also senses the guidance radar to enable comparisons that enhance the missile ' s resistance to passive jamming . Principle of guidance ( semi - active version ) . The launching aircraft will illuminate the target with its radar . In radars of the 1950s these were single target tracking devices using a nutating horn as part of the antenna . This caused the beam to be swept in a small cone . Signal processing would be applied to determine the direction of maximum illumination and so develop a signal to steer the antenna toward the target . The missile detects the reflected signal from the target with a high gain antenna in a similar fashion and steers the entire missile toward closure with the target . The missile guidance also samples a portion of the illuminating signal via rearward pointing waveguide s . The comparison of these two signals enabled logic circuits to determine the true target reflection signal , even if the target were to eject radar - reflecting chaff .