9K31 Strela - 1 The 9K31 " Strela - 1 " ( ; ) is a highly mobile , short - range , low altitude infra - red guided surface - to - air missile system . Originally developed by the Soviet Union under the GRAU designation 9K31 , it is commonly known by its NATO reporting name , SA - 9 " Gaskin " . The system consists of a BRDM - 2 amphibious vehicle , mounting two pairs of ready - to - fire 9M31 missiles . Development History . The missiles used in this system were developed alongside the ubiquitous Russia n MANPADS 9K32M " Strela - 2 " ( NATO designation SA - 7 " Grail " ) in the 1960s . At first both missiles were intended to be man - portable systems , but as it became obvious that Strela - 2 would be far more compact of the two system , the development goals of Strela - 1 were changed . Instead of a battalion - level man - portable system the new criteria called for a regimental vehicle - mounted SAM to support the ZSU - 23 - 4 . As a result of the change in role and more relaxed weight limits of a vehicle - mounted SAM , the design team made the 9M31 a much heavier missile , which permitted fewer design compromises than in the case of Strela - 2 to achieve acceptable kinematic performance . The most notable difference is the much larger diameter of the missile and a blunt seeker head that occupies the full width of the missile body . With all else being equal , the ability of an optical seeker to detect a target is directly proportional to its diameter , but on the other hand aerodynamic drag increases proportionally to the square of the diameter . The Strela - 1 also had a warhead over twice as heavy , a proximity fuze and more effective control surface configuration to provide better maneuverability at the cost of increased drag . The net result was a missile four times the weight of Strela - 2 , with only slightly longer reach but otherwise of much better performance . Vehicle . Each TEL carries four ready - to fire missiles , but typically no missiles for reloading . Reloading is performed manually and usually takes approximately 5 minutes . The missile boxes are lowered for transport to lower the total height of the vehicle . The driver and commander have periscopes for viewing outside the vehicle when the hatches are closed . Apart from the new turret , the other major change to the BRDM - 2 chassis is the removal of the belly wheels ( which are presumably to improve off - road performance ) . The driver and commander both have infra - red vision systems . The vehicle has standard NBC ( Nuclear , Biological and Chemical ) protection including overpressure . The missiles fold down to the sides of the turret which greatly reduces the height of the vehicle whilst travelling . Each vehicle weighs around 7 tonnes ( 7 . 7 short tons ) and has a 104 kW ( 140 hp ) engine and a central tire pressure control system . Missiles and guidance . 9M31 . According to a number of Russian sources the original 9M31 ( US DoD designation SA - 9A " Gaskin - Mod0 " ) had a zone of reliable target destruction from 900 to 4200 metres . Several western and also some Russian sources give much higher range estimates of 800 to 6500 m ( 0 . 5 to 4 miles ) ; these may refer to maximum firing range against an approaching target and minimum against receding , which are obviously larger envelopes as the target only has to reach the intercept zone by the time the missile would reach it . The missile is effective against targets receding at a maximum speed of 220 m / s , or approaching at 310 m / s . The warhead was primarily intended to impact the target directly , and had contact and magnetic fuzes , but also contained a back - up optical proximity fuze to detonate the warhead in case of a near miss . The missile also had an unusual safety mechanism in case of a miss ; rather than a self - destruct fuze , if the optical fuze didn ' t detect a target within 13 . . . 16 seconds , the warhead safety mechanism would be engaged to prevent its detonation upon impact . Propulsion is by a single - stage solid fuel rocket motor , which is ignited at a distance of few meters from the launch tube : as the throw - out charge ejects the missile from its canister , it is trailing a wire from its rear . The main rocket ignites when missile reaches the wire ' s end at a few metres distance , and is cut off from it . The seeker head is an unusual construction , using uncooled lead sulphide ( PbS ) detector elements , but with an unusual tracking mechanism . Uncooled PbS elements are commonly used to detect radiation at only short wavelengths of less than 2 micrometers . Only very hot objects emit strongly at such short wavelengths , limiting heat - seeking systems using uncooled PbS detector elements to rear - hemisphere engagements against jet targets , although propeller - driven aircraft and helicopters can of course be engaged from any direction from which the exhaust or other very hot parts of the engine are visible . The seeker head of 9M31 , however , utilizes the PbS elements differently from usual . Taking advantage of the fact that the clear sky gives strong and constant background emission at below 2 micrometer range , peaking at visual light ( 0 . 4 to 0 . 7 micrometer ) wavelengths at which PbS in 295 kelvins temperature still provides a response , the seeker head is used to track a change of radiation from the target compared to the background . The method is called optical photocontrast homing ( Rus . : фотоконтрастное наведение ) . The advantage of photocontrast homing method over traditional heat - seeking homing heads using PbS elements is that it negates the most serious drawback of early - generation IR - homing missiles : complete lack of front - aspect engagement capability against approaching jets . Even early cooled seeker heads had usually only limited forward hemisphere engagement abilities , often reducing to zero in case of jets approaching exactly towards the shooter . The new photo - contrast seeker had its own serious limits also , however , which came in the form of rather strict meteorological conditions that had to be met in order to enable the seeker to detect and track the target : it could only engage targets against background conditions of either clear sky or solid overcast , minimum of 20 degrees away from the sun , and at least 2 degrees above horizon . Nonetheless , following a study of battlefield conditions and aircraft tactics in past conflicts where short - range air defences had been used , it was concluded that conditions allowing the use of such homing system were common enough to make it a cost - effective design choice and a better trade - off than the only practical alternative available at the time , which was infrared homing restricted to rear - hemisphere engagements . No doubt the fact that Strela - 1 would be supplemented by IR - homing Strela - 2 and radar - controlled ZSU - 23 - 4 self - propelled AA gun system may have influenced the decision in favour of such an unusual homing system . The main advantage the choice was that it made Strela - 1 the only ADA system in the Soviet tank or motor rifle regiment that could engage approaching targets out to a range of several kilometers - the ZSU being hampered by very short range , and Strela - 2 by its limitation to tail - chase engagements of ground attack jets , after the jet had already delivered its attack . 9M31M . While the 9M31 was accepted to service after state trials in 1968 , the trials committee also suggested improvements that should be incorporated into the weapon as soon as possible . As a result of these improvements the 9M31M " Strela - 1M " ( US DoD designation SA - 9B " Gaskin - Mod0 " ) entered service in 1970 . The new version introduced many slight improvements in performance characteristics of the missile : it had a slightly heavier warhead , more accurate guidance system to increase the probability of direct impacts , and extended range . Range is again reported to be as high as 8000 m ( 0 . 35 to 5 miles ) in a number of western and also a few Russian sources , whereas for example Petukhov & Shestov , Lappi , and a number Russian web sources give much more modest performance figures ; considering the performance of similar systems , at least an intercept range of 8000 m seems unlikely for such a small , high - drag missile design . Deployment . The Strela - 1 was deployed in short - range air defence batteries of Soviet motor rifle and tank regiments . The battery consisted of a gun platoon of four ZSU - 23 - 4 Shilkas , and a SAM platoon with four Strela - 1 vehicles . The Strela - 1 platoon contains , in addition to a command vehicle , one TEL fitted with a passive radar detection system similar to a Radar Warning Receiver , and several more ( usually three ) without any radar system . The radar detection system is the 9S16 " Flat Box " and consists of four sensors mounted around the BRDM vehicle giving it 360 degree coverage . This system emits no radar energy but can detect radio waves emitted from aircraft , giving the vehicle warning about incoming aircraft and aiding in the acquisition of the target aircraft with the optical system . Typical tactics call for the launch of two missiles against each target to improve the chance of destroying it . In Russia , the 9K31 Strela - 1 system was superseded by the 9K35 Strela - 10 .