Skys are cause by hitting down to hard on the ball. or by just teeing it up to high, the highest you should tee the ball is so half the ball is above the face of your driver. If the ball it teed up to high the club will just go under the ball and pop it up in the air. If you are swaying or chaning your spine angle you will find that you will come way to steep which will pop the ball up. You could also be doing everything right with a perfect swing but the ball could be to far back in your stance, so the club is hitting the ball on the downswing. remember the driver hits up on the ball on the up swing. fairway woods sweep the ball off the turf. so the need to be closer to your front foot.