The Raven (the ride that this accident occurred on) has seatbelt-type restraints that the rider can buckle and unbuckle at will, but also a wretched individual lap bar that only the operator can lock and unlock (so if you're sitting with a large person and you're little, it can still crush your internal organs). Since Tammy Fellner was tiny (100 lbs), I assume not only did she unbuckle the seat belt, but she was also able to shimmy out of the lap bar and stand up (if the witnesses are speaking the truth).