You would be AMAZED at what can be done with a leaning tree. A few years ago I had a youngster helping me remove a few trees up behind the shop on our property. I dropped all of them but one small tree, which was leaning HEAVILY in one direction. I watched him make a notch, and I walked away, figuring it would be nearly IMPOSSIBLE to get that tree to swing around apprx 90 degrees where the shop roof would be in jeapardy. A few seconds later I looked up just in time to see the tree swinging over 90 degrees to the left, it actually came around far enough that it almost missed the shop and fell between the shop and the house.
The damage was minor, simply because the tree was so small, at best apprx 8" in diameter. We still had to rebuild one truss and replace an 18' portion of the sheet metal roof. I went back to the stump to analyze the cut. Everything looked good, except a solid 4" of material was left on the left side only, between the cuts, which essentially "pulled" the tree and caused it to fall apprx 120 degrees from the direction of it's steep lean. Evidentally, during the second cut, he cut ALL of the material loose on the right side first, leaving apprx 4" of material on the left side when the tree decided to start it's fall. Lesson learned, NEVER assume a leaning tree needs any less attention to detail that a straight one! Youngsters, even under watchful eye shouldn't be allowed on trees which have any potential of reaching structures. 3rd and most important lesson, NEVER take you eyes off anyone, at any experience level during the process!.....FWIW....Cliff