It does not matter what is the axis called, what I meant is that I want my RC to follow the spline, but align the tilt of the object according to the surface below it, which happens when I tick "Align Y with Surface". For that to work, a surface needs to be provided to the generator, but when it is, surface automatically used for UP/DOWN of the RC segments too and spline is then only used for LEFT/RIGHT BACK/FORTH.
Is there a way to tilt my segments to the surface below it yet the positioning of the segments would still follow the spline just as if a surface was not provided?