Don't fell a tree when you're tired. I was pretty well played out by the time I had the truck loaded but wanted to put the next tree on the ground. Willow about 30" at butt, developed into several main stems up about 8', real bad lean and very top heavy. Cleaned the brush off the base as high as I couild reach with the 193T. Grabbed the 441 Magnum to lay it down. First mistake was to fire up the saw without really thinking about what I was doing. Lean was too sever to even think aobut an undercut - jam the bar for certain. So I figured just cut from back side till the tree fell. I have done dozens of them over the last 40 years. Laid into the tree and got about 1/3 way when I saw the split start. Really bad barber chair - the third one I have had. 1st one chaired when the undercut closed up (two shallow of a notch). Second one was taking a stem out of a 3-stem tree. I expected that one to chair and it did - perfectly safe for me though.
This one almost cost me a new pair of work pants. Got away as far as I could but only made about 10'. Tree came to rest with the 'hinge' about 15' off the ground and the butt hanging just about straight up above me.
What caused it? Stupidity. I did every thing possible to ensure it would chair and didn't even think about it. In the past I have ALWAYS, chained or strapped a leaner above the cut, didn't even think about it this time. I have also bore cut in leaving a bit on the bottom side then cut the top side. Considered it for about 1 sec and but for some unknown reason didn't do it.