Improving the Continued Airworthiness of Civil Aircraft A Strategy for the FAAs Aircraft Certification Service

Introduction

Theair transportation system in the United States is safer than comparablemodes of public transportation. For major airlines (i.e., air carriersoperating under Part 121 of the Federal Aviation Regulations [FARs]),the average number of fatalities per 100 million passenger miles isabout 0.7, compared to about 1.8 for automobiles, about 11 forintercity buses, and about 17 for trains (BTS 1998a, 1998b, 1998c,1998d; NHTSA, 1996). In terms of safety, travel on major airlineswithin the U.S. is matched only by travel on major airlines in otherhighly developed countries. Nevertheless, fatal accidents are alwaystragic, and complacency on the part of the FAA or industry is not anappropriate response. In fact, the FAA has already established astrategic goal of zero accidents.

The Federal Aviation Administration (FAA) plays a major role in promoting aviation safety.¹However, the FAA will face several important challenges in the future.If the aircraft accident rate remains constant or slowly decreases, theannual number of accidents will swell as the number of flightsincreases to meet consumer demands. The public has the right to expecthigh levels of safety, and it is incumbent upon industry and the FAA toimprove the effectiveness of their safety programs. In part, this meansreacting to major accidents by taking aggressive action to preventsimilar accidents, but without detracting from ongoing safety programsto address other risks.

Almost all aircraftaccidents are caused by a chain of events, the elimination of any oneof which could have prevented the accident. The most common link inthese chains involves human factors (pilots, air traffic controllers,maintenance crews, etc.). However, in some cases, one or more links inthe accident chain are associated with the design of the aircraft.Either a design deficiency results in an equipment malfunction thatleads to an accident, or a design enhancement could have prevented anunexpected event from resulting in an accident.

The FAA’s Aircraft Certification Service (AIR)²is responsible for promoting the safety of new aircraft by certifyingthat they meet established safety standards. Certification includestype certificates (certification of all-new aircraft designs), amendedtype certificates (certification of derivative aircraft designs basedon previously certificated products), production certificates(certification of a manufacturer’s ability to produce aircraft inconformance with a certificated design), and airworthiness certificates(certification of the airworthiness of each newly manufacturedaircraft). AIR also promotes the continued airworthiness of existingaircraft by mandating modifications when operating experience indicatesthe presence of a real or potential hazard.³

Aspart of the FAA’s efforts to improve aviation safety, AIR chartered theNational Research Council to examine safety-related elements of thecertification and continued air-worthiness process and to recommend anapproach to improve AIR’s risk evaluation and risk management. Inresponse, the National Research Council’s Aeronautics and SpaceEngineering Board formed the Committee on Aircraft Certification SafetyManagement. This report is the result of the study conducted by thatcommittee. A complete list of the committee’s findings andrecommendations appears in Appendix A.

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