The helicopter had to let it go after it was flying out of control after the initial 5 miles in the sling.
Sounds like it wasn't set up properly. It requires a very special preparation, like spoilers on the wings etc, so that the aircraft does not 'fly' while being slung, as well as slinging to keep it in line with the airflow and stop it spinning in the rotor wash. Wonder whose chopper it was?
DF.