I am with you, https://en.m.wikipedia.org/wiki/Earth-centered,_Earth-fixed_coordinate_system https://en.m.wikipedia.org/wiki/Earth-centered,_Earth-fixed_... wou

I am with you, https://en.m.wikipedia.org/wiki/Earth-centered,_Earth-fixed_coordinate_system https://en.m.wikipedia.org/wiki/Earth-centered,_Earth-fixed_... would be my preference, too. Especially if we’re talking internal representation. My background is having to track objects that fly or go below the surface. Though as others have mentioned, asking “is this object on the ground currently” is a tiny bit complicated.