Spline track transform

Hi there, first off I’ll admit to not looking very thoroughly at other threads, I am making a sort of flight simulator. The way it works is that you can select a flight path and input a starting latitude, longitude, and altitude to change the starting location. The issue that I’m having is that is seems like the spline track that I’m using as a path seems to be rotated when I change starting locations (i.e. if the path takes you left for however many meters when starting in arizona, it takes you that far down towards the surface of the earth when starting in massachusetts).