From experience, the NATO Seasparrow missile will launch and have a burn time for an X amount of seconds, after that it will coast to its target, bleeding speed all the way. In effect, it won't smoke anymore so you won't see it coming in the first place.
Secondly, it has an open hydraulic system, meaning that the servos that activate its flight surfaces have a limited amount of oil to play with, after the oil is gone, the missile is basically an expensive lawn dart. It can manoeuvrer three times or so and than it's out of oil.
So, at launch, it will be proportionally guided to an impact point somewhere at the intercept of the tracks of both target and missile. If the target manoeuvrers, the missile looses speed and oil up to the point where it cannot manoeuvrer.
The missile in the SA-13 is optical/IR guided so the exploding fuel tanks would make an excellent target for any IR missile, it's guidance totally blinded by the huge fireball. The RWR might go off due to the SA-13 carrying a small ranging radar but after launch, that's basically it. Burn time a couple of seconds and then it's over.