Osa (SA-8 Gecko)

   The Osa (wasp) is a short-range surface-to-air missile system. Its reporting name in the West is SA-8 Gecko.

   Its development commenced in 1960. It was developed in response to the US Mauler SAM system. Later the US project ran into problems and was eventually cancelled. The Osa entered service with the Soviet Army in 1971. This air defense system was used by motorized infantry units. Production ceased in 1989. Since its introduction this air defense system was exported to a number of countries. Currently the Osa and its variants are used by 19 countries, including Russia (400), Belarus, Greece (39), India (48), Poland (64) and Ukraine.

   The Osa was the first production mobile air defense missile system with radar and missiles on a single vehicle. For the first time a single vehicle could detect, track and engage aircraft. This system is used against aircraft and helicopters in any kind of weather.

   Initial production version has four missiles. These had a maximum range of 10 km and maximum altitude of 5 km. Later production version, the Osa-AK carries six missiles in containers. Maximum range increased to 12 km. Missiles have contact and proximity fuses. Kill probability for the early production system is 35-85%, depending on altitude. On later production models kill probability increased to 55-85%. The Osa can not launch missiles on the move. It launches them from stationary position or from short stops.

   The Osa can also operate independently. Its radar has acquisition range of about 30 km. Some sources clam that it detects aircraft at a range of up to 40 km. System can search for targets while on the move. Tracking range is about 20 km. On either side of the tracking radar there is a small parabolic dish antenna to track the missile. So up to two missiles can be guided simultaneously on a single target. Furthermore both of these missiles are guided on different frequencies, to complicate electronic countermeasures. This SAM missile system can also operate with the aid of regimental surveillance radars. Reaction time from target detection to launch is 26 seconds.

   Vehicle has a crew of five. It seems that this vehicle is fitted with NBC protection system. The Osa can stop from travelling and prepare for engagement within 4 minutes.

   This air defense system is based on a BAZ-5937 6x6 amphibious wheeled chassis. It is powered by a turbocharged diesel engine, developing 300 hp. It is also fitted with auxiliary gas turbine power unit, which powers all systems when the main engine is turned off. First and third axles are steered. Vehicle is fitted with a central tyre inflation system. However some sources claim that cross-country mobility of this vehicle is limited. Chassis of this air defense missile system is fully amphibious. On water it is propelled by two waterjets. This air defense system can be also transported by air by Il-76 or similar military cargo aircraft.

   There is also a reloading vehicle, which is based on a similar BAZ-5939 chassis. It carries 18 reload missiles in containers and is fitted with a crane. All six missiles are reloaded within 5 minutes.

   A battery of Osa consists of 4 combat vehicles and 2 reloading vehicles.

Variants

   Osa (SA-8) initial production version fitted with 4 missiles. It entered service with the Soviet Army in 1971;

   Osa-M (SA-N-4 Gecko) a naval version of the system. It has two missiles on a retractable rotating launcher. It was introduced in 1971-1972;

   Osa-AK (SA-8B) fitted with six missiles. Missiles have a maximum range of 12 km. It was introduced in 1975;

   Osa-AKM fitted with new missiles. Maximum range was extended to 15 km. It has improved kill probability against low flying helicopters. It is worth noting that previous systems were not effective against helicopters flying just above tree tops. This system was introduced in 1980;

   Osa-1T a Belorussian upgrade. Combat vehicle is based on the previous BAZ-5937 of the new MZKT-69222 wheeled chassis. Missiles have a maximum range of 20 km;

   Osa-AKM-P1 Zadlo, a Polish upgrade of the system.