An accident is an event that is both unusual and unexpected. An
accident may or may not be caused by the negligence of a person. An issue
that you must decide is whether any act or omission of the defendant
violated a legal duty so as to constitute negligence.
An accident is unavoidable if it is not caused by the negligence of
either party and if it could not have been foreseen and avoided by the use
of what has previously been defined for you as ordinary care.