I work in construction and have many licenses and training certificates and one of them is fall protection.

Safety belts can do more harm than good. Safety harnessess can do more harm than good IF not properly worn. It is amazing how many people do not wear one properly. It is also amazing how many people will tie the rope too loose, and if they fall will fall the entire 6 foot distance. One of the things we were taught is a 150 pound man will be jerked by the rope in a sudden stop with 1,000 pounds of force. that is like being hit by a small car going 20 mph.

One other thing to consider is you will not fall straight down, rather you will fall away from the tree and the rope will slam you into the tree. Remember the car hitting you?

The only safe harness is a full body harness that puts you in a sitting postion when hanging from the rope, and it must fit snugly enough that it feels a little uncomfortable when standing, yet loose enough to not stop circulation. The rope must be attached properly also. When sitting and you lean forward slightly you should feel the tension of the rope. This way if you fall, it won't be very far, and the bottom of your stand will be near your chest or shoulders.