Interpretation ID: aiam0619
Chairman of the Board
Rose Manufacturing Co.
2700 West Barberry Place
Denver
CO 80204;
Dear Mr. Rose: Thank you for your letter of February 1, 1972, concerning the Nationa Highway Traffic Safety Administration (NHTSA) pamphlet, 'What to Buy in Child Restraint Systems.'; While you approve generally of the pamphlet, you state that yo consider certain statements in it to be incorrect. Particularly, you disagree with two statements appearing on the page of the pamphlet discussing child harnesses. Those statements were: 'Give preference to those which attach under the seat back, not over it.', and, 'Give preference to those which either attach directly to the vehicle floor, or to the vehicle seat belt, not to the seat back.' We do not agree that either of these statements is incorrect.; The NHTSA position is that child harnesses that attach over or directl to the vehicle seat back increase the chance of seat back failure, a hazard which you recognize in your letter. Our dynamic test data have shown that affixing a child harness in either of these ways can cause the inertial load of the child to be applied to the seat back excessively deforming or failing the seat back, thereby allowing excessive occupant excursion and increasing the chance of injury to the child. In short, these configurations increase rather than, as you seem to argue, decrease the chance of seat back failure.; With regard to the statements concerning compressive forces bein applied to the child during a crash, while we agree in principle that such forces are undesirable, it is not clear from your letter how their application is prevented by having the child harness attach over the top of the vehicle seat. In any event, it is preferable, in our view, for some force to be applied to the child's torso, as long as it is evenly distributed, than to have the child flung into hostile surfaces within the vehicle.; We also do not agree with the statement on page 2 of your letter tha harnesses can safely be attached to a vehicle seat back, as the seat back is '...in turn securely attached to the car floor.' Our experience has been quite the opposite, vehicle seat backs are merely attached to the seat frame and are quite susceptible to collapse in crash situations.; Finally, we do believe the pamphlet, in its recommendation that a chil should not stand on the front seat of the vehicle when the harness is attached, is consistent with the design of your harness in that both seek to reduce the danger of whiplash injury.; I hope this clarifies our position for you. Sincerely, Charles H. Hartman, Deputy Administrator