Upon the trial defendants called, as an expert witness, a professor of mechanical and aerospace engineering, who had also been previously employed as a consulting engineer in the field of accident analysis and reconstruction. He testified to an extensive background in the use of seat belts in both the aircraft and automotive industries. Over plaintiff's objection, the expert was permitted to give his opinion that "The seat belt is an extremely effective device in either preventing or alleviating injury." More specifically, he stated that the seat belt is the most effective improvement that has been made in the automobile in the last 20 years. After viewing photographs of the vehicles and the accident scene, the expert opined that had the plaintiff been wearing a seat belt, she would not have been ejected from her automobile; and that had she not been ejected, she probably would not have been seriously injured. When asked on cross-examination if the fact that plaintiff was ejected from her automobile might have saved her life, the engineer stated that "the worst thing that could have happened to her [was] being ejected from the vehicle.