I suppose I see "North" as more of a function rather than a variable. When you specify North you're specifying a relative direction. Because the vector one takes to go North from the US is not the same vector one takes from Russia. The issue is we're mapping a direction to a point on a sphere So yes North isn't an absolute vector, but it is a shortcut to calculating the vector to the location you want to go. If I was writing this function, I could easily add in a check to determine if we're heading towards the equator before we hit North or not based on the vector direction. And just keep it stuck to the sphere's normal. The initial inclination would be used for calculating the initial vector. I think our wires are getting crossed cause I'm used to 3d programming and velocity is usually spd * (x, y, z) and the inclinations and such you're speaking of are baked into the (x, y, z) vector that is calculated to determine the "direction" part of the "direction + magnitude" definition of a vector. (I'm enjoying this by the way)