It doesn't work when spawned in verticaly. It's a normal issue.

I'm having an issue where when I launch them they go straight up in the air and fall back down onto the launcher, but I'm using the programmer and inputting the correct X and Y coordinates into it. How can I fix this?

Would 0 work for the altitude of the target if the target is on the ground?

i mean fair enough but i use it for most of my stuff (not even just gps some of my sarh missiles use it) and it works quite well most of the time, only issue is that you have to be moving for it to work but realistically that isnt a problem for missiles

Good idea DJ but it's not that accurate. I have a GPS speed recorder that could be used for that but it's not accaurate enough.

where is the solid rocket fuel for this? Did you modify XML to fit it together?

hey dude just to let you know you dont need the compass and tilt sensor inputs, you can use the delta of the coordinates to calculate the missiles moving trajectory, using the deltas of each coordinate like this:
atan(delta x,delta y) for compass, atan(delta z,sqrt(delta x^2+delta y^2)) for pitch angle

this works best in lua but should work in function blocks

Dude you are the best