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M-4 Osa-M


NATO: SA-N-4 Gecko


Overview

Osa-M

Osa-M system with ZIF-122 launcher with 9M33M missiles in foreground and associated fire control radar in the background.
Source: Unknown author - © Copyright lies with original owner

Origin
Soviet Union
Type
Naval SAM system
Entered service
1971
Status
In service
Development
1960’s
Developer
Soviet Union
Production
1970 - ?
Producer
Soviet Union
Designations
SA-N-4 Gecko (NATO reporting name)
M-4 (Soviet navy designation)
4K33 (GRAU index for system)
9M33M (GRAU index for missile)
Pop Group (NATO reporting name for radar)
Notable users
Soviet Union
Russia

Description

Introduction

The Osa-M is a naval SAM system of Soviet origin. It was developed to act as a point defense system against aircraft and inbound anti-ship missiles. Over time it was upgraded to for more effectiveness against low flying targets.

Design

The Osa-M is derived from the land based 9K33 Osa self-propelled SAM system. There is a 70% commonality in missile design and guidance systems. Whereas the land based 9K33 is one of the first self-propelled SAM systems where radars, operators and missiles are on the same vehicle, the Osa-M has a more modular layout. The search and fire control radar are located away from the ZIF-122 twin rail launcher. A unique feature of the launcher is that when it the system is not in use the launcher is retracted below deck and covered by a large round door.

Guidance

Targets are identified by the ship’s main air surveillance radar and handed off to the Osa-M system. The guidance section consist of a tracking radar and a fire control radar. NATO reporting name is “Pop Group”. The tracking radar provides targets coordinates while the fire control radar is used to plot the course between the missile in flight and the target. The 9M33M missile uses command guidance via radio frequency. A single target is engaged at a time.

Firepower

The ZIF-122 launcher has two missiles ready to launch. 40 additional missiles are stored in the magazine below deck. The maximum range is about 10 km and targets may be engaged out to altitudes of over 3.5 km. The main role of the Osa-M is to intercept inbound subsonic anti-ship missiles. Therefore all upgrades were focussed at the minimum altitude. With the latest modification sea skimming missiles 5 m above sea level can be engaged.

Platforms

The Osa-M was fitted to a variety of Soviet ships. These range from corvettes to cruisers. Minimum ships size for the Osa-M is quoted as 500 t displacement. Over time the Osa-M system was supplemented in the anti-missile role by combined gun and missile systems such as the Kashtan.

Variants

ZIF-122 with 9M33M missiles

Moskva missile cruiser Osa-M air defense system off the coast of Syria on December 18, 2015
Source: Russian MoD - © GNU Attribution Share Alike license

Variants of the Osa-M system

Osa-M
Original naval SAM system based on the 9M33 missile. Introduced in 1971. This variant uses the 9M33M surface to air missile.
Osa-MA
Improved Osa-M system. Capable of engaging targets 25 to 60 m above sea level. Adopted in 1979. This version uses the 9M33M1 Osa missile, and can launch the older 9M33M as well.
Osa-MA2
Further upgrade of the Osa-M system. Able to engage sea skimming targets as low as 5 m above sea level. Introduced in the mid 1980’s. This version uses the 9M33M1 missile. Some reports indicate that it is compatible with the improved land based 9M33M3 missile.

Details

Facts ZIF-122
General
Origin
Soviet Union
Type
Naval SAM launcher
Dimensions
Weight
6.85 t without missiles
Over 12 t with missiles
Characteristics
Design
Retractable twin rail launcher
Capacity
2 missiles ready to launch
40 missiles in magazine
Reload time
16 to 21 seconds
Missile types
9M33M Osa-M
Launch interval
2 missiles per minute

9M33 Osa

The M-4 Osa naval surface to air missile system fires the 9M33M and 9M33M1 missiles.

Read more about 9M33 Osa

Media

Platforms

Note: incomplete list

Project 1239 Sivuch class

Soviet class of surface effect guided missile corvettes. Two ships in class. Armed with Osa-MA2.

Read more about Project 1239 Sivuch class

Project 1164 Atlant class

Soviet class of cruisers. Three ships completed. Fitted with two Osa-MA2 system.

Read more about Project 1164 Atlant class

Project 1174 Nosorog class

Soviet class of landing platform dock. Three ships completed. Fitted with one Osa-M in first in class and one Osa-MA inrest of class.

Read more about Project 1174 Nosorog class

Related articles

3K95 Kinzhal

The Kinzhal system was developed as the successor for the M-4 Osa-M system. It is point defense system with much improved capability versus sea skimming missiles.

Read more about 3K95 Kinzhal