Evaluation of the Transport Airplane
Risk Assessment Methodology

Committee on Transport Airplane Risk Assessment Methodology

Aeronautics and Space Engineering Board

Division on Engineering and Physical Sciences

A Consensus Study Report of

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This activity was supported by Contract 693KA9-21-T-00009 with the Federal Aviation Administration. Any opinions, findings, conclusions, or recommendations expressed in this publication do not necessarily reflect the views of any agency or organization that provided support for the project.

International Standard Book Number-13: 978-0-309-31573-9
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Digital Object Identifier: https://doi.org/10.17226/26519

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Suggested citation: National Academies of Sciences, Engineering, and Medicine. 2022. Evaluation of the Transport Airplane Risk Assessment Methodology. Washington, DC: The National Academies Press. https://doi.org/10.17226/26519.

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COMMITTEE ON TRANSPORT AIRPLANE RISK ASSESSMENT METHODOLOGY

GEORGE T. LIGLER, NAE,¹ GTL Associates and Texas A&M University, Chair

ERIC ALLISON, Joby Aviation

JOHN-PAUL B. CLARKE, The University of Texas at Austin

LETICIA CUELLAR-HENGARTNER, Los Alamos National Laboratory

KAREN M. FEIGH, Georgia Institute of Technology

JEFF GUZZETTI, Guzzetti Aviation Risk Discovery, LLC

RONALD J. HINDERBERGER, The Boeing Company (retired)

ZAHRA MOHAGHEGH, University of Illinois at Urbana-Champaign

PAUL MORELL, American Airlines (retired)

JAN C. SCHILLING, NAE, General Electric Aviation (retired)

ROBERT E. VOROS, Merlin Labs, LLC

AMIR YACOBY, NAS,² Harvard University

Staff

ARUL MOZHI, Senior Program Officer

LINDA WALKER, Program Coordinator

ALAN ANGLEMAN, Associate Director, Space Studies Board and Aeronautics and Space Engineering Board, Study Director

COLLEEN N. HARTMAN, Director, Space Studies Board, Aeronautics and Space Engineering Board, and Board on Physics and Astronomy

___________________

¹ Member, National Academy of Engineering.

² Member, National Academy of Sciences.

AERONAUTICS AND SPACE ENGINEERING BOARD

ILAN KROO, NAE,¹ Stanford University, Chair

BRIAN M. ARGROW, NAE, University of Colorado Boulder

ROBERT D. BRAUN, NAE, NASA Jet Propulsion Laboratory

EDWARD F. CRAWLEY, NAE, Massachusetts Institute of Technology

WILLIAM R. GRAY III, United States Air Force

SUSAN J. HELMS, NAE, Orbital Visions, LLC

JOHN C. KARAS, Lockheed Martin Space Systems Company

ANDREW R. LACHER, Noblis

NICHOLAS D. LAPPOS, NAE, Sikorsky, a Lockheed Martin Company

GEORGE T. LIGLER, NAE, GTL Associates

LESTER L. LYLES, NAE, United States Air Force

VALERIE MANNING, Airbus

PARVIZ MOIN, NAE/NAS,² Stanford University

DARRYLL J. PINES, NAE, University of Maryland

ROBIE I. SAMANTA ROY, Electra.aero

WANDA A. SIGUR, NAE, Independent Consultant

DAVID W. THOMPSON, NAE, Orbital ATK, Inc.

ANTHONY M. WAAS, University of Michigan

MICHAEL I. YARYMOVYCH, NAE, Sarasota Space Associates

SHERRIE L. ZACHARIUS, Aerospace Corporation

Staff

COLLEEN N. HARTMAN, Director

ALAN ANGLEMAN, Associate Director

DWAYNE DAY, Senior Program Officer

MARGARET A. KNEMEYER, Financial Officer

RADAKA LIGHTFOOT, Senior Financial Associate

ARUL MOZHI, Senior Program Officer

DANIEL NAGASAWA, Program Officer

CELESTE A. NAYLOR, Information Management Associate

TANJA PILZAK, Manager, Program Operations

ANDREA REBHOLZ, Program Coordinator

___________________

¹ Member, National Academy of Engineering.

² Member, National Academy of Sciences.

Acknowledgment of Reviewers

This Consensus Study Report was reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise. The purpose of this independent review is to provide candid and critical comments that will assist the National Academies of Sciences, Engineering, and Medicine in making each published report as sound as possible and to ensure that it meets the institutional standards for quality, objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process.

We thank the following individuals for their review of this report:

Although the reviewers listed above provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations of this report nor did they see the final draft before its release. The review of this report was overseen by John J. Tracy, NAE, The Boeing Company (retired), and Roger L. McCarthy, NAE, McCarthy Engineering. They were responsible for making certain that an independent examination of this report was carried out in accordance with the standards of the National Academies and that all review comments were carefully considered. Responsibility for the final content rests entirely with the authoring committee and the National Academies.

___________________

¹ Member, National Academy of Sciences.

² Member, National Academy of Engineering.

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Preface

The origin of this study is a mandate contained within the Aircraft Certification, Safety, and Accountability Act,¹ signed into law on December 27, 2020. In accordance with this Act, the Federal Aviation Administration (FAA) entered into a contract with the National Academies of Sciences, Engineering, and Medicine (the National Academies) to conduct a study to assess the Transport Airplane Risk Assessment Methodology (TARAM) process used by the FAA.

This report responds to the statement of task specified in the Aircraft Certification, Safety, and Accountability Act. It must be noted at the outset that this report does not assess the application of the TARAM process to any specific incidents or accidents, including the 737 MAX accidents. While the committee was provided a copy of the 737 MAX TARAM analysis provided by the FAA to Congress in late 2019, FAA management declined to provide additional details or to discuss the TARAM analysis of the 737 MAX with the committee. The committee, therefore, was unable to comment on the 737 MAX TARAM analysis. Regardless, the committee was able to make recommendations that, if adopted, would significantly improve the TARAM process.

The study statement of task is as follows:

• Review the role and objectives of TARAM within the FAA’s overall safety oversight system,
• Assess the TARAM analysis process,
• Assess the effectiveness of the TARAM for the purposes of improving aviation safety, and
• Provide recommendations to improve the methodology and effectiveness of the TARAM as an element of aviation safety.

This statement of task requires a deep understanding of the TARAM process, its usage, what inputs TARAM needs, the source of these inputs, and who executes the TARAM process. From the TARAM analysis prediction to incorporating TARAM results into the FAA’s continued operational safety (COS) decision-making process, the overall TARAM process was studied.

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¹ This Act is part of the Consolidated Appropriations Act, 2021, included in it as DIVISION V—Aircraft Certification, Safety, and Accountability.

To understand the study origin and context, the committee heard from the congressional committee staff. To understand the TARAM analysis process and how it is used in support of aircraft COS, the committee held informational reviews with the FAA leadership team. These were followed by informational reviews with key FAA technical experts responsible for the formulation of the TARAM process. To understand how the Aircraft Certification Offices (ACOs) use the TARAM process, the committee received a briefing on the Seattle ACO Transport Airplane Safety Manual and examples of its use. To further assess whether parameters within the TARAM analysis process are similar with other industry or federal agency processes that deal with safety concerns, the committee received presentations from the National Aeronautics and Space Administration and from the U.S. Nuclear Regulatory Commission on how risk analysis is used for decision-making.

The committee also independently reviewed the FAA’s Policy Statement PS-ANM-25-05 Risk Assessment Methodology for Transport Category Airplanes dated November 4, 2011, referencing Safety Management System, the FAA’s Aircraft Certification Service Order 8110.107A Monitor Safety/Analyze Data dated October 1, 2012, the FAA’s Transport Airplane Risk Assessment Methodology (TARAM) Handbook dated November 4, 2011, and Seattle ACO’s Transport Airplane Safety Manual, released September 1, 2021. This was completed to understand not only the defined ownership for TARAM analysis and its details but also the FAA’s role in assessing unsafe conditions.

George T. Ligler, Chair
Committee on Transport Airplane Risk Assessment Methodology

Contents

SUMMARY

1 INTRODUCTION

Study Origin

Statement of Task

Study Scope

Study Approach

Report Content

2 OVERVIEW OF TARAM

TARAM in a Nutshell

Current TARAM Process

Input Data to TARAM

Use of the TARAM Results in COS Decision-Making

3 ROLE OF TARAM WITHIN THE FAA’S OVERALL SAFETY OVERSIGHT SYSTEM

TARAM and MSAD in the Context of Safety Oversight

TARAM in the Context of Rulemaking

TARAM in the Context of Type Certification

4 IMPROVEMENTS FOR THE INPUT DATA TO TARAM

Improving Completeness, Accessibility, and Quality of Input Data to TARAM

Characterizing Uncertainty in Input Data to TARAM

5 IMPROVEMENTS TO THE TARAM PROCESS

Improving Systematic Risk Modeling in the TARAM Process

Incorporating Human Reliability Analysis in the TARAM Process

Incorporating Software Reliability Analysis in the TARAM Process

Incorporating Uncertainty Analysis in the TARAM Process

6 IMPROVEMENTS FOR THE USE OF TARAM OUTPUTS

Improving Uncertainty Consideration in TARAM Decision-Making Guidance

Incorporating Risk Importance Ranking in TARAM Decision-Making Guidance

Improving the Quality of the COS Decision-Making Process When Using the TARAM Results

APPENDIXES

A Current TARAM Process Details

B Committee Members and Staff Biographical Information

C Acronyms and Abbreviations