Analysis of trends in aviation maintenance risk: An empirical approach

Safety is paramount in the airline industry. A significant amount of effort has been devoted to reducing mechanical failures and pilot errors. Recently, more attention has been devoted to the contribution of maintenance to accidents and incidents. This study investigates and quantifies the contribution of maintenance, both in terms of frequency and severity, to passenger airline risk by analyzing three different sources of data from 1999 to 2008: 769 NTSB accident reports, 3242 FAA incident reports, and 7478 FAA records of fines and other legal actions taken against airlines and associated organizations. We analyze several safety related metrics and develop an aviation maintenance risk scorecard that collects these metrics to synthesize a comprehensive track record of maintenance contribution to airline accidents and incidents. We found for example that maintenance‐related accidents are approximately 6.5 times more likely to be fatal than accidents in general, and that when fatalities do occur, maintenance accidents result in approximately 3.6 times more fatalities on average. Our analysis of accident trends indicates that this contribution to accident risk has remained fairly constant over the past decade. Our analysis of incidents and FAA fines and legal actions also revealed similar trends. We found that at least 10% of incidents involving mechanical failures such as ruptured hydraulic lines can be attributed to maintenance, suggesting that there may be issues surrounding both the design of and compliance with maintenance plans. Similarly 36% of FAA fines and legal actions involve inadequate maintenance, with recent years showing a decline to about 20%, which may be a reflection of improved maintenance practices. Our results can aid industry and government in focusing resources to continue improving aviation safety.