For one reason or another this crane was ready to be climbed. Tower cranes have back moment (they weight more in the back then the front) so in order to be climbed they must be balanced. You can guess pretty closely at the balance point of a crane. Since you are supposed to pin or bolt the climber off to positively attach the crane to the climber, you only have to be in the ball park. These idiots didn't connect the climber to the superstructure and removed the bolts from the mast to the superstructure. The result is a beautiful dismount fortunately not killing anyone.
Fortunately a gentleman caught in on camera and you can see it here.
The very thing happened in Seattle in the 80's as well. The crane punched through six floors of parking structure before coming to a rest. The operator popped his head out of the cab and yelled "I'm alive!" in astonishment. Again, lawyers make this stuff disappear. I wonder if anyone at Sellen would like to find them for educational purposes?