You cannot knock something off course when it has no course. Switch that to your BRAHMOS. A straight line of flight with its engine and not gravity as its main delivery means. Hit the back of the missile and you lost your engine, not to mention being knocked off your line approach. Doesn't make any sense to me.If the scud was like throwing a stone then it's trajectory is definitely lot more predictable.Other than that patriots have a homing in radar. As it gets closer to its target, the image in its sensors gets larger and larger. Now consider patriot missile against a cruise missle. Aren't cruise missiles terrain hugging ? They evade the radar and fly low. Mid course guidance can also be given. This makes the trajectory difficult to detect .It's definitely not flying with a parabola trajectory, the way the scuds were. So, it's going to be the other way round and not as the officer says. No disrespect. For your information, unlike sidewinders patriots work on Radar and not heat signature.