The Isayev S-125 Neva/Pechora (С-123 "Нева"/"Печора", NATO reporting name SA-3 Goa) Soviet surface-to-air missile system was designed to complement the S-25 and S-75. It has a shorter effective range and lower engagement altitude than either of its predecessors and also flies slower, but due to its two-stage design it is more effective against more maneuverable targets. It is also able to engage lower flying targets than the previous systems, and being more modern it is much more resistant to ECM than the S-75. The 5V24 (V-600) missiles reach around Mach 3 to 3.5 in flight, both stages powered by solid fuel rocket motors. The S-125, like the S-75, uses radio command guidance. The naval version of this system has the NATO reporting name SA-N-1 Goa and original designation M-1 Volna (Russian Волна – wave).
The S-125 was first deployed between 1961 and 1964 around Moscow, augmenting the S-25 and S-75 sites already ringing the city, as well as in other parts of the USSR. In 1964, an upgraded version of the system, the S-125M "Neva-M" and later S-125M1 "Neva-M1" was developed. The original version was designated SA-3A by the US DoD and the new Neva-M named SA-3B and (naval) SA-N-1B. The Neva-M introduced a redesigned booster and an improved guidance system. The SA-3 was not used against U.S. forces in Vietnam, because the Soviets feared that China (after the souring of Sino-Soviet relations in 1960), through which most, if not all of the equipment meant for the NVA had to travel, would try to copy the missile. It has seen some service in the Israeli-Arab wars.
The S-125 is mostly obsolete now due to its short range and easily jammed radar but Serbian sources claim that despite this an S-125 system managed to shoot down an F-117 Nighthawk "Stealth Fighter" on March 27 1999 during the Kosovo War (the only recorded downing of a stealth aircraft). The S-125 used had been modified by colonel Zoltán Dani in order to detect stealth aircraft.
The "Neva-M" upgrade gives the new 5V27 (V-601) missiles the capability of being launched against surface targets including ships due to their improved guidance which allows them to dive down onto their target with a parabolic-type trajectory (somewhat ballistic in nature).
The S-125 is somewhat mobile, an improvement over the S-75 system. The missiles are typically deployed on fixed turrets containing two or four but can be carried ready-to-fire on ZIL trucks in pairs. Reloading the fixed launchers takes a few minutes.
The S-125 system uses 2 different missiles versions. The V-600 (or 5V24) had the smallest warhead with only 60 kg of High-Explosive. It had a range of about 15 km.
The later version is named V-601 (or 5V27). It has a length of 6.09 m, a wing span of 2.2 m and a body diameter of 0.375 m. This missile weighs 953 kg at launch, and has a 70 kg warhead containing 33 kg of HE and 4,500 fragments. The minimum range is 3.5 km, and the maximum is 35 km (with the Pechora 2A). The intercept altitudes are between 100 m and 18 km.
The launchers are accompanied by a command building or truck and three primary radar systems:
"Flat Face"/"Squat Eye" is mounted on a van ("Squat Eye" on a taller mast for better performance against low-altitude targets), "Low Blow" on a trailer and "Side Net" on a box-bodied trailer.
Work on a naval version M-1 Volna (SA-N-1) started in 1956, along with work on a land version. It was first mounted on a rebuilt Kotlin class destroyer (Project 56K) Bravyi and tested in 1962. In the same year, the system was accepted. The basic missile was a V-600 (or 4K90) (range: from 4 to 15 km, altitude: from 0.1 to 10 km). Fire control and guidance is carried out by 4R90 Yatagan radar, with five parabolic antennas on a common head. Only one target can be engaged at a time (or two, for ships fitted with two Volna systems). In case of emergency, Volna could be also used against naval targets, due to short response time.
The first launcher type was the two-missile ZIF-101, with a magazine for 16 missiles. In 1963 an improved two-missile launcher, ZIF-102, with a magazine for 32 missiles, was introduced to new ship classes. In 1967 Volna systems were upgraded to Volna-M (SA-N-1B) with V-601 (4K91) missiles (range: 4-22 km, altitude: 0.1-14 km).
In 1974 - 1976 some systems were modernized to Volna-P standard, with an additional TV target tracking channel and better resistance to jamming. Later, improved V-601M missiles were introduced, with lower minimal attack altitude against aerial targets (system Volna-N).
Some Indian frigates also carry the M-1 Volna system.
Since Russia replaced most of its S-125 sites with SA-10 and SA-12 systems, they decided to upgrade the S-125 systems being removed from service to make them more attractive to export customers. Released in 2000, the Pechora-2 version features better range, multiple target engagement ability and a higher probability of kill (PK). The launcher is moved onto a truck allowing much shorter relocation times. It is also possible to fire the Pechora-2M system against cruise missiles.
In 1999, a Russian-Belarusian financial-industrial consortium called Oboronitelnye Sistemy (Defensive Systems) was awarded a contract to overhaul Egypt's S-125 SAM system. These refurbished weapons have been reintroduced as the S-125 Pechora 2M.
In 2001, Poland began offering an upgrade to the S-125 known as the Newa SC. This replaced many analogue components with digital ones for improved reliability and accuracy. This upgrade also involves mounting the missile launcher on a T-55 tank chassis (a TEL), greatly improving mobility and also adds IFF capability and data links. Radar is mounted on an 8-wheeled heavy truck chassis (formerly used for Scud launchers). Serbian modifications include terminal/camera homing from radar base. During the Kosovo war, Yugoslav Army SA-3 missiles also shot down numerous UAV's, one F-117 and an F-16C.
Later the same year, the Russian version was upgraded again to the Pechora-M which upgraded almost all aspects of the system - the rocket motor, radar, guidance, warhead, fuse and electronics. There is an added laser/infra-red tracking device to allow launching of missiles without the use of the radar.