Well, I just had this happen. Hollow silver maple, broke at the base while I was climbing. I knew it was hollow, but I thought it would hold. One of my guys suggested I tie into the tree behind it so I threw my rope into a crotch I deemed worthy. By the time I was high enough to start cutting my rope was at too high of an angle and slid down the branch to a y. When the tension came off my climbing line putting my full weigh onto the tree, it broke. By the time the tree hit the chimney, most of the weight was on my rope, cushioning the blow to the chimney enough to cause no damage. My lanyard was around the tree too, so my climbing system was now the rigging holding up the tree. My guys got ropes to me which I was able to throw into the other tree and they tied it off so I could climb down. We were then able to rig the tree off of the house. No damage, no injuries, but a hell of a close call. Next time, I will take the time to set my climbing line better and set a rope or ropes from the ground to stabilise the tree. Too many years of climbing trees like this without incident definitly made me a little complacent. Complacency gets experienced climbers killed. I know that, but I guess I needed this to bring it to a point of action.