I remember reading a report about it in an old Amusement Park Journal.
My memory is not totally solid on the incident, but around the mid 80s, the back car of the King Cobra derailed, but was still attached to the rest of the train, dangling. I think the derailment brought the train to a stop on the lower portion of a turn, possibly in the helix. Again, if I remember correctly, there were no serious injuries, everyone just had to be evacuated, and it was a little tricky for those on the dangling car. It was a bad accident, but thankfully the restraints kept everyone safe, the the ride still operates to this day safely. The cause? I can't remember, but I think it was kind of "freak" accident.
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- Peabody