Evaluation of Interaction of Inflatable Seat Belts with CRS Installed in Aircraft Seats in Oblique Impact Sled Tests

Principal Investigator: Aditya Belwadi, PhD, Children’s Hospital of Philadelphia

Below is an executive summary of this project. Please note that this summary describes results and interpretation that may not be final. Final interpretation of results will be in the peer-reviewed literature.

Sled test of a forward-facing CRS installed using a deactivated inflatable seat belt and Hybrid III 3-year-old ATD

Federal Aviation Administration (FAA) regulations allow children younger than two years of age to ride unrestrained; however, the FAA strongly recommends that all children who fly, regardless of age, should be restrained in the appropriate child restraint system (CRS) for their weight and size attached to the aircraft seat by the aircraft seat belt.

The methods and fixtures used to certify child restraints under automotive regulation Federal Motor Vehicle Safety Standard 213 may not effectively measure CRS performance in an airplane seat. Compounding this, aircraft passenger seats continue to evolve, with the latest development being a partially enclosed (pod) seat that is oriented obliquely with respect to the aircraft centerline, presenting an off-axis loading condition.

The long-term objective of this line of research is to evaluate the effectiveness of advanced restraint systems and aircraft seats for pediatric occupants and their ability to mitigate injury during various modes of impact. The aim of the current study was to evaluate the interaction of an inflatable aircraft seat belt with rear-facing (RF) and forward-facing (FF) CRS installed on aircraft seats in oblique sled tests.

Six static installation evaluations and 17 dynamic oblique sled tests were performed. Seven RF and 10 FF CRS were attached to a FAA rigid couch, configured to reflect the typical oblique aircraft seat configuration. CRSs were mounted via a 2-point lap belt of two designs - with a deactivated inflatable air bag and with a standard aircraft lap belt. A Q1 anthropomorphic test device (ATD), or crash test dummy, representing a 1-year-old, and a Hybrid III 3-year-old ATD were secured to the CRS using the 5-point harness system. Occupant kinetics, including head, chest and pelvic accelerations, along with kinematics captured via high-speed camera were evaluated against standard Injury Assessment Reference Values (IARV) for injury thresholds. Eleven out of the 17 tests were run with the addition of a sidewall or an armrest to evaluate the likelihood of head contact.

In static testing, the thickness of the inflatable seat belt proved challenging during installation of the RF CRSs, particularly if the CRS had a base. In this scenario, the belt could not be routed and this scenario was therefore not tested dynamically. In dynamic testing, installation of the CRS via the inflatable seat belt resulted in head, chest and neck accelerations as well as Head Injury Criterion (HIC) values below the IARVs. No significant differences were noted between the inflatable belt and a standard lap belt. Neck Injury Criterion was greater than 1.0 for all test conditions, but was not significantly different across seat belt type. There was no visible head strike with the armrest or the side cabin wall in any of the tests.

The test data can be used by the FAA to develop further policies on using CRSs in aircraft seats, especially when installed using inflatable seat belts. 

Project Team Member

Hans W. Hauschild, MS, Medical College of Wisconsin

IAB Mentors

Amanda Taylor, Federal Aviation Administration