Safety Study

Airbag Performance in General Aviation Restraint Systems

NTSB Number SS-11/01
NTIS Number PB2011-917001
PDF

EXECUTIVE SUMMARY

In 2003, airbags were first certificated for pilot and copilot seats on general aviation (GA) aircraft, and as of August 2010, they have been installed in nearly 18,000 seats in over 7,000 GA aircraft. Unlike automotive airbags that typically deploy from the steering wheel, instrument panel, or above the window, airbags in GA aircraft are installed in the lap belt or shoulder harness portions of the restraint system and are designed to deploy outward from the pilot or occupant. Sled tests conducted under controlled conditions have suggested that aviation airbags may increase survivability and reduce injury in actual aviation accidents; however, no systematic evaluations have been conducted to evaluate their efficacy in real world scenarios. Therefore, in 2006, the National Transportation Safety Board (NTSB) initiated an exploratory case series study to assess airbag performance in GA accidents. The goals of the study were (1) to examine the effectiveness of airbags in mitigating occupant injury in GA accidents, (2) to identify any unintended consequences of airbag deployments, and (3) to develop procedures to assist investigators in documenting airbag systems in future investigations.

During the 3-year data collection period, researchers tracked 145 notifications of events (including 88 accidents) involving airbag-equipped airplanes and conducted field investigations of 18 of those events. Ten airbag-equipped GA airplane accidents involving 25 occupants met the study criteria and were subjected to a full review and analysis by a multidisciplinary team. The accidents represented a range of crash severities and included survivable accidents with and without airbag deployments. There were no unexpected deployments or unintended consequences identified during the study period. Overall, when adjusted correctly, the deployment of the airbag systems did not result in any negative outcomes, and in certain cases, deployment may have mitigated the severity of occupant injuries.

Of the 88 accidents involving airbag-equipped airplanes that were identified during the study period, about two-thirds (66 percent) had no airbag deployment and no occupant injuries. An additional 22 percent had reductions in survivable space or crash forces that were not survivable. Therefore, airbags would only have been expected to yield a benefit in a relatively small (12 percent) proportion of accidents. Within that window of accident severity, the NTSB concludes that aviation airbags can mitigate occupant injuries in severe but survivable crashes in which the principal direction of force is longitudinal.

During the course of the study, the study team also discovered several potential issues that may compromise occupant safety associated with the use, adjustment, or design of restraint systems. The report discusses steps that could be taken to address these safety issues and suggests future research directions in the area of GA occupant protection.

Finally, as a result of the study, guidance for NTSB investigators was developed and disseminated, including a formal process for gathering data about airbag installations and deployments in accident aircraft.