well it is true and when i got off and told the ride operator, they said this could be because i pulled the harness down too tight, which i gotta admit it felt really tight and there was no give like normal.. so its my own fault i suppose. and well if it was impossible why is that safetybelt there? surely thats for back ups incase it did happen! so unless u were there you can judge what i'm sayin!
If it did happen you the ride would be shut right away, to prevent anything happening on any other trains, and H&S would have to check the ride over, the seat belts are actualy there because, if you do decide you dont want your harness fully down and a little gap between your legs and the harness this belt stops all chances of you slipping out of the ride, the belts are nothing to do with the harness opening system.