Long-range surveillance and target acquisition is handled by the van-mounted P-15 FLAT FACE) radar. The P-15 radar has been replaced in many S-125 units by the P-15M SQUAT EYE radar, which has the antenna mounted on a 20-30 m mast for improved low altitude coverage. The accompanying PRV-11 SIDE NET E-band height-finding radar has a range of 180 km covering targets at altitudes of up to 32000 meters.
FLAT FACE P-15
Function: Target acquisition
Range 200-250 km
Frequency C band (UHF)
Associated weapon system SA_3 GOA possibly SA-8 GECKO SAM, LOW BLOW missile control radar
Comments Can guide three missiles simultaneosly / Power 380kw / BW AZ 4.3deg-ELEV 4.3 deg / PW 2us / PRF 200-700pps/ 70km range at 300m alt/ accuracy 650m range, 1.8 deg AZ
Recognition: Van mounted / Two eliptical parabolic reflectors measuring 11x5.5 m / Reflectors arranged one above the other on van roof

Target data generated by these tracking radars is passed to the battalion's LOW BLOW trailer-mounted fire control radar. With a maximum acquisition range of 110 km, the tracking range of this I-band system is between 40-85 km, depending on target size and altitude. The system can simultaneously track six target aircraft and guide one or two missiles. Improved LOW BLOW radars include TV cameras with a range of 25 km to provide the fire control team with the data needed to perform a command guidance intercept in a heavy ECM environment. If the missile fails to intercept it would be commanded to either change trajectory or self-destruct.

The S-125 is fired from trainable launchers which are normally fixed, but can be relocated. The crew loads the missiles with the aid of a conveyor onto the ground-mounted, trainable launcher for firing, with both twin and quadruple launchers in use. A pair of missiles are carried in tandem on a modified truck or tracked vehicle. The S-125 is normally transported from battalion storage areas on modified ZIL-131 (6 x 6) or ZIL-157 (6 x 6) trucks and loaded onto the launchers. Approximately one minute is required to load the missiles onto the launch rails, but nearly an hour is required between missile launches due to missile preparation, truck transit and other reloading procedures