Horizontal Swing Plane (Swing Direction for Trackman Users) tells us the direction of the swing arc, relative to the target line. A positive value means the arc is to the right of the target, negative means it is to the left.
In simpler terms, the HSP is the direction that your hula hoop (swing arc) is pointed. It is the direction of your swing as seen from a bird’s eye view.
*Important* This is purely the horizontal direction and NOT the 3D Club Path. This does not take Vertical Swing Plane or Angle of Attack into account.