Here is the simple fact about staying on plane in your golf swing: doing so means your shot will travel far and straight. An off-plane swing, however, will cause a dreaded slice or hook.
What does "on plane" mean? Trackman defines swing plane as "the vertical angle between the ground and the circle that the club head travels on during the bottom portion of the swing arc."
Staying on plane means your club has stayed on that arc throughout the entire swing. Here are some ways to execute a proper on-plane swing and enjoy the long, straight shots that it produces.
As you begin your takeaway, keep your hands, arms, and shoulders moving together as one unit. This will help your club stay on the correct path, promoting a wide arc and resulting in more distance.
Sweep the club head back, keeping it close to the ground for about the first 10 inches of your takeaway. At the halfway point of your backswing, your club should be parallel to the target line.
At the top of your backswing, your right arm (right handed golfers) should be in an L-shaped position, with your right elbow pointing toward the ground. The left elbow should remain straight.
Your club face should be square at the top so the club is parallel to your left forearm. Make a big shoulder turn. Your left shoulder should sit under your chin, and your back should be facing the target for maximum power as you uncoil and begin your downswing.
If your takeaway and backswing are correct and are on the right path, the downswing should be a continuation and culmination. This is where your power is unleashed. Your club head should be square at impact with your hands slightly ahead. If your left shoulder is slightly higher than your right, it's a good indication that your posture and plane are correct.
Shift your weight from your trail side to your lead side and come to a balanced finish with 90 percent of your weight on your front foot.
A steep swing path above plane will result in a swing that comes over the top, causing the ball to slice. A swing path that is below the ideal plane, or too flat, will cause a duck hook to the left or a blocked shot to the right.
Remember, achieving a consistent golf swing that's on plane takes a lot of dedication and practice. It's important to stay patient and, most of all, enjoy the game.