The missile knows where it is at all times. It knows this because it knows where it isn't, by subtracting where it is, from where it isn't, or where it isn't, from where it is, whichever is greater, it obtains a difference, or deviation. The guidance sub-system uses deviations to generate corrective commands to drive the missile from a position where it is, to a position where it isn't, and arriving at a position where it wasn't, it now is

I got my account back boi.

+rep lost his sweetroll

fimsh