Infant restraint systems in air transport: injury risk and prevention
Creators: name: Shrimpton, Adam
Publisher: name: RMIT University
Year: 2024

description: Aviation safety regulations in Australia and overseas permit the carriage of an infant passenger on the lap of an adult; however, this practice is known to be unsafe in an emergency landing scenario. While automotive child restraint systems (CRS) have been found to provide adequate protection to infant passengers, safety issues associated with their use have been identified. Principally, they may interfere with the dynamic behaviour of the aircraft seat, increasing the risk of injury to an adult seated directly behind.<br><br>This study compared and evaluated the safety of seating arrangements involving infant air transport passengers under emergency landing conditions. Two arrangements were considered: the infant was either held on the lap of an adult or seated in a forward-facing CRS. A partially validated numerical model was used to study seat behaviour and measure injury potential. Results were analysed to compare the safety of different configurations, to evaluate safety in terms of an occupant protection standard and to predict the occurrence and severity of a particular injury using existing biomechanical relationships.<br><br>One of two practices applies to lap-held infants depending on the jurisdiction a flight is operating under: the infant is either unrestrained or restrained by a supplementary loop belt. This study found that an unrestrained infant is likely to be projected through the aircraft cabin during the impact sequence while a restrained infant is at risk of serious abdominal injuries. Though the adoption of an emergency brace position by an adult carrying a lap-held infant was found to be beneficial, infant injury potential remained high. Of the three brace positions studied, a modified position proposed by this study was the most effective in reducing head injury potential for the infant.<br><br>Three CRS installation methods - the aircraft seat lap belt, ISOFIX and LATCH - were analysed in terms of CRS performance and behaviour. Each method adequately protected the CRS occupant. The ISOFIX method resulted in a small increase in head injury potential for an adult seated directly aft while in the lap belt and LATCH cases a significant increase was observed.<br><br>Some airlines specifically prohibit the use of Australian-certified CRS, presumably due to a requirement for installation using a ‘top tether’ strap. This study found that the use of a top tether does not present any benefit in terms of CRS motion or injury potential for the CRS occupant.<br><br>This study makes four recommendations:<br><br>1. The practice of holding an infant passenger on the lap should be prohibited. Until this is the case, advice on emergency brace positions involving lap-held infants should be revised to include a lateral offset between the head of the infant and that of the adult. <br><br>2. The use of automotive child restraints to restrain infant passengers should be mandated.<br><br>3.  Any requirement for the use of a top tether in aircraft CRS installations should be removed.<br><br> 4. Child restraint systems should be installed in outboard seats directly forward of a bulkhead, unoccupied space or another CRS.