OVERVIEW: The SA-9 Gaskin (Russian name 9K31 Strela-1) is a highly mobile, short-range, low altitude, infra-red guided surface-to-air transporter-erector-launcher (TEL) mounted on the BRDM-2 chassis. 

DETAILS: The SA-9 Gaskin / 9k31 Strela-1 utilizes optical target acquisitioning and is fed azimuth, altitude, and range information from the divisional air defense regiment command post's target acquisition radars and then use their optical tracking sights to acquire targets. The original production 9M31 missile was a first-generation uncooled infra-red seeker missile that had limited ability to acquire lock-on of approaching aircraft due to using a photo-contrasting method to achieve lock-on through the seeker head of the missile.  The 9M31 was quickly upgraded to the 9M31M variety by 1970, with the newer missile having improved lock-on ability and greater target sensitivity than the original, although the missile still has a considerably reduced range when engaging approaching aircraft. One TEL out of the missile platoon will be an SA-9A and will be equipped with a passive radar detection system similar to a radar warning receiver. This system is known as the 9S16 "FLAT BOX A" and consists of a series of sensors mounted on the outside of the vehicle that provide 360-degrees coverage. The FLAT BOX A is an entirely passive system and is capable of detecting radar emmissions from approaching aircraft and aids in target acquisition with the optical system. This entry represents the SA-9B and does not mount the FLAT BOX A. 

NOTES: The SA-9 Gaskin / 9k31 Strela-1 was introduced in the mid 1960's to complement the ZSU-23-4 SPAAG in the air defence batteries of Soviet motor rifle and tank regiments. The regimental air defence battery consists of a missile platoon of four SA-9's and a gun platoon of four ZSU-23-4's. For offensive operations the ZSU's typically operate approximately 400m behind the lead elements of the motor rifle and tank regiments, while the SA-9's deploy further back around the regimental command post. In the defense, the SA-9's and ZSU-23-4's will typically be dug in to minimize visual detection and will provide air defense support to the forward battalions (ZSU-23-4) and regimental command post (SA-9). The SA-9 was widely exported by the Soviet Union and has been used operationally in the Middle East and Africa.

SOURCES: Global military army magazine defence security industry technology news exhibition world land forces - Army Recognition. "SA-9 Gaskin 9K31 Strela-1 ground to air missile system technical data sheet specifications - Army Recognition - Army Recognition." Accessed November 6, 2013. http://www.armyrecognition.com/russia_russian_missile_system_vehicle_uk/sa-9_gaskin_9k31_strela-1_ground_to_air_missile_system_technical_data_sheet_specifications.html ; FM 100-2-3. Washington D.C.: Headquarters, Department of the Army, 1991