This is what happens when people don't know what they are doing. I've worked in construction 30 years and never had anything like this happen. Know how much the load weighs. Use rigging rated for whatever your lifting. I always used rigging rated much higher than the load we were lifting. Use tag lines. You don't want to lift something 15 story's in the air over people on the ground and take a chance of the rigging breaking. We always used red danger tape to tape off the lifting area and posted people around the lifting area to make sure no one went through the red tape. You definitely want a qualified crane operator that knows the lifting capacity of the crane. You also want the person doing the rigging know what they are doing.