[Jim.Cook]

Golf Club on Plane (2-F) - There are some very simple but very accurate checks for being "on Plane." Whenever the Clubshaft is parallel to the ground it must also be parallel to the base line of the Inclined Plane which is usually (but not always) the Line of Flight also. Otherwise, the end of the Club that is closes to the ground must be pointing at the base line of the Inclined Plane--or extensions of that line, even if they must be extended to the horizon.

I hope I'm not picking nits but...

You say " when ever the clubshaft is parallel to the ground it must be also parallel to the base line...." At address, start your back swing and stop when the club is parallel to the ground. Since you are making a perfect backswing it is on plane. Now, swing the club parallel to the ground until it is straight out in front of you. It no longer is parallel to the base line or line of flight but it remains parallel to the ground plane.

When two non-parallel non- coexistant planes meet they form a line. The golfer positions himself so that the line of flight formed by the intersection of the club plane and the plane of the earth is directed at his target. To monitor the path of my club, to make sure that the plane my club is moving on has not wavered, I make sure the lowest end of the club is always pointing to the original flight line established during my impact set.

Weather this is correct or not, this has been the single biggest item that has straightened out my ball flight.