It was my second year of logging for firewood when this happened to me.
A kind elderly lady allowed me to take out three rows of dead green ash trees down the center of her shelterbelt here in North Dakota. All of the trees had died due to flood water. Most of the trees had already fallen over, and many were hung up in other downed trees. A lot of careful planning goes into making even a single cut, as the physics of the fall must be planned out. Most of the time I get it right.
On this particular morning, I came across three trees that had piled atop one another. Standing below, I tried to figure out what would happen if a made a cut here, and then a cut there, and so on. I made my first cut, then all hell broke loose. The bottom tree began to lean over toward me, then snapped. I stepped back, tripped over a bunch of underbrush, and watched as the whole mess headed right for me. The bottom tree......the one holding the whole mess up, managed to get caught in a crotch of a tree just above my head, stopping the whole mess dead in its tracks. I had about three feet of free space to crawl out from under that mess.
Lesson learned. I now use supporting ropes or cables, attached to healthy nearby trees, when tackling similar situations.
Joel