Infants in rear facing child seats are at significant risk from deploying air bags, since the rear facing orientation of the child seat places their heads extremely close to the air bag cover. This is why NHTSA emphasizes that rear facing infant seats must never be placed in the front seat unless the air bag is turned off.
In order to address the risks air bags pose to infants in rear facing child seats, NHTSA is proposing two alternative test requirements, the selection of which would be at the option of the manufacturer. The two manufacturer options are: (1) test requirements for an automatic air bag suppression feature or (2) test requirements for low-risk deployment involving deployment of the air bag in the presence of a 12-month old Crash Restraints Air Bag Interaction (CRABI) dummy in a rear facing child restraint.
If the automatic suppression feature option were selected, the air bag would need to be suppressed during several static tests using, in the right front passenger seat, a 12 month old child dummy in a rear facing infant seat, and also during rough road tests. The rear facing infant seat would be placed in a variety of different positions during the static tests. In order to ensure that the suppression feature does not inappropriately suppress the air bag for small statured adults, the air bag would need to be activated during several static tests using a 5th percentile adult female dummy in the right front passenger seat, and also during rough road tests using that dummy.
The agency is proposing rough road tests to address the possibility that some types of automatic suppression features, e.g., weight sensors, might be "fooled" by occupant movement associated with riding on rough roads. For example, depending on the design of the sensor, occupant movement such as bouncing might cause the weight sensor to read a higher weight or lower weight. The agency believes that such devices should be designed so they do not turn on the air bag in the presence of a small child who is bouncing as a result of riding on a rough road, and so that they do not turn off the air bag in the presence of a small-statured adult who is bouncing as a result of riding on a rough road.
If the automatic suppression feature option were selected, a manufacturer would be required to provide a telltale light on the instrument panel which is illuminated whenever the passenger air bag is deactivated and not illuminated whenever the passenger air bag is activated. This telltale would advise vehicle occupants of the operational status of the air bag. In addition, the agency would use the telltale to determine, during the tests discussed above, whether the air bag is appropriately activated or deactivated.
If the low risk deployment option were selected, a vehicle would be required to meet specified injury criteria when the passenger air bag is deployed in the presence of a 12 month old child dummy placed in a rear facing infant seat. The agency is proposing injury criteria appropriate for a 12 month old child.
In the case of air bags with multiple inflation levels, the injury criteria would need to be met for all levels.
NHTSA notes that there are uncertainties associated with all of the injury criteria proposed by this notice, especially those for children. Because experimental test data are generally not available from children, it is necessary to estimate injury tolerances by other means, e.g., by applying scaling methods to adult data. Particularly because injury mechanisms may differ in some respects between adults and children, there are necessarily some uncertainties associated with injury criteria developed by these means.
NHTSA requests comments on how to take account of these uncertainties in this rulemaking. For example, the agency is proposing a HIC limit of 660 for the 12-month old CRABI dummy in a rear facing child restraint. However, there are uncertainties as to how much risk of injury is represented by this value. The agency requests commenters to address the appropriateness of the proposed value, and on whether the agency should permit a low risk deployment option or instead require suppression for infants in rear facing child restraints.
With respect to that part of the proposed low risk deployment option that would require injury criteria limits to be met for all levels of a multi-level air bag, NHTSA notes that a child in a rear facing infant seat would be extremely close to the passenger air bag in any crash, regardless of crash severity. Moreover, based on discussions with suppliers and vehicle manufacturers, the agency believes that the development of technologies which suppress the passenger air bag in the presence of a rear facing infant seat is nearing completion. Thus, it appears reasonable to expect advanced air bag designs to essentially eliminate risk of serious injury or fatality resulting from air bag deployment to children in rear facing infant seats. Of course, even with advanced air bags, children in rear facing infant seats, like other children, will be safer in the back seat.
Under both test procedures, manufacturers would be required to assure compliance in tests using any child restraint capable of being used in the rear facing position which was manufactured for sale in the United States between two years and ten years prior to the date the first vehicle of the model year carline of which the vehicle is a part was first offered for sale to a consumer. This would ensure that vehicle manufacturers take account of the variety of different rear facing child restraints in use as they design their systems. The restraints used for compliance testing could be unused or used; however, if used, there could not be any visible damage prior to the test. The agency requests comments on whether there are alternative means of achieving this result, e.g., specifying use of several representative devices.
NHTSA is proposing to specify use of the 12 month old CRABI dummy. The motor vehicle industry is familiar with this dummy, and the agency expects to propose adding it to Part 572 later this year.
