This demonstrates just how dangerous cutting trees down (especially large ones) can be.
Recently, while clearing a section of my property I cut down a large poplar tree that I estimated to be about 70 feet tall and was about 3 feet across the trunk. The tree was situated close to several other large trees and a building so it needed to be directed in a specific direction to avoid hitting any obstacles or snagging in another tree. Snags are the most dangerous of all and are to be avoided at all costs.
To get the desired results and avoid injury or damage, I planned my escape route then attached a hand winch cable in the top of the tree using the trunk of another tree as a deadman and tightened the winch just enough to apply pressure in the right direction to make the fall more predictable.
I then proceeded to cut an open faced notch that faced the desired direction of fall and cut through the back side only enough to allow wedges to be inserted. The wedges prevent the tree from squatting down on the saw during the initial cutting and are then used to send the tree on it's way when a desired hinge thickness is reached. The hinge is a section of wood that is left to ensure that the tree goes where you want it to.
I then proceeded to drive the wedges deeper while carefully watching the top of the tree for signs (movement in the direction of travel) that it was about to go over. Cracking sounds are usually heard as well. When I was sure the tree was committed to going over, I backed away at a 45 degree angle (escape route) and cried "timber" to alert that the tree was falling.
My father-in-law had offered to use his tractor to anchor (pull) the tree but I refused because I knew it was too dangerous and opted to use the hand winch instead. Luckily I had too, because after it was all over, I realized that during the last moments of the fall, when the tree hit the ground, it had snapped the winch cable and wrapped it around the anchor tree leaving several prominent scars. Had that been a person, who knows the damage it could have caused.
One should never even think about cutting down a tree unless they know what they are doing. Accidents can happen in a flash, even to people with experience.