If you have a Six Iron and Strike the Ball while the Clubshaft is Vertical to the Ground, with a Level Left Wrist at Impact, then your Clubshaft will be on the Elbow Plane.
If you used the same Six Iron and Strike the Ball while the Clubshaft is leaning Forward 6 degrees or so with the Clubface Square to Target, with a Level Left Wrist at Impact, then your Clubshaft will be on the Turned Shoulder Plane.