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Evaluation of the Transport Airplane Risk Assessment Methodology (2022)

Chapter: 6 Improvements for the Use of TARAM Outputs

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Suggested Citation:"6 Improvements for the Use of TARAM Outputs." National Academies of Sciences, Engineering, and Medicine. 2022. Evaluation of the Transport Airplane Risk Assessment Methodology. Washington, DC: The National Academies Press. doi: 10.17226/26519.
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6

Improvements for the Use of TARAM Outputs

This chapter provides an analysis of findings of the gaps identified by the committee in the current continued operational safety (COS) decision-making guidance and process. Recommendations for improvements are also provided.

IMPROVING UNCERTAINTY CONSIDERATION IN TARAM DECISION-MAKING GUIDANCE

Upon implementation of the recommendations presented in Chapters 3 and 5, the Transport Airplane Risk Assessment Methodology (TARAM) outputs will be obtained as the combination of the point estimates (or the average values) and the uncertainty measures (such as confidence intervals and percentiles) as a result of propagating uncertainty. Neither the current TARAM Handbook nor Federal Aviation Administration (FAA) Order 8110.107A provides explicit guidance on how uncertainty associated with the TARAM risk outputs should be considered in the COS decision-making process. The current practice of uncertainty consideration in Monitor Safety/Analyze Data (MSAD), using the TARAM results, is limited to qualitative considerations. Based on the FAA briefing regarding the Seattle Aircraft Certification Office (ACO) Transport Airplane Safety Manual, sensitivity analyses are sometimes reported to the Corrective Action Review Board (CARB) as part of the TARAM results and considered in COS decisions. The current consideration of sensitivity analyses in COS decision-making is limited to checking the impact of a bounding input value or assumption on the TARAM risk outputs in the one-at-a-time method, rather than checking the aggregated impact of all the dominant uncertainty sources on the risk outputs considering the possible ranges of input values or assumptions and their potential interactions.

Figure 6.1 depicts the concept of uncertainty consideration in the comparison between the risk values and the risk guidelines. In this figure, four different cases (A to D) are illustrated in terms of the relationship of the point estimate and uncertainty bound of the risk outputs with the risk guidelines.

For each case, the point estimate represents the “average” risk output, while the uncertainty bound indicates probabilistic quantification of the aggregated impact of epistemic uncertainty on the risk output. In Case A, as both the point estimate and the uncertainty bound are below the risk guideline, this case can be judged to satisfy the risk guideline with a reasonable level of confidence; hence, the decision to accept this case can be made with sufficient clarity. In Case D, as both the point estimate and the uncertainty bound are above the risk guideline, this case can be judged as not satisfying the risk guideline with a reasonable level of confidence; hence, the decision to reject this case can be made with sufficient clarity. For Cases B and C, the uncertainty bounds overlap with the risk guideline, indicating that the current state of knowledge and analysis cannot provide the sufficient level

Suggested Citation:"6 Improvements for the Use of TARAM Outputs." National Academies of Sciences, Engineering, and Medicine. 2022. Evaluation of the Transport Airplane Risk Assessment Methodology. Washington, DC: The National Academies Press. doi: 10.17226/26519.
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Image
FIGURE 6.1 Concept of uncertainty considerations recommended by the committee for the COS decision-making based on the TARAM results.

of confidence needed to make a clear decision; hence, special care is warranted in the decision-making process for these situations. Examples of the options for these situations are (1) reduce the uncertainty by further data collection and model refinements and (2) carry out decision-making by placing more emphasis on other safety principles such as safety margin and backup for the required safety function. Because Cases B and C have the largest potential for unsafe decisions, specific guidance on the treatment of these situations in the COS decision-making process could be established.

The uncertainty associated with the TARAM risk outputs could be considered in both (1) the CARB decision as to whether the condition under study is unsafe (Step 5.0 of the MSAD process flow in FAA Order 8110.107A, Figure 2) and (2) the CARB decision on the urgency and priority of each issue determined by CARB to require corrective actions (Step 9.0 of the MSAD process flow in FAA Order 8110.107A, Figure 6). The guidance on uncertainty treatment in these COS decision-making steps could be provided as part of the TARAM Handbook and/or FAA Order 8110.107A.

Finding: The FAA’s current in-service safety decision-making guidance for transport category airplanes considers only the point estimates of risk from TARAM. Limited uncertainty consideration is sometimes provided based on one-at-a-time sensitivity analyses using bounding input values and assumptions. There is no full consideration of uncertainty associated with the TARAM risk outputs in comparison with the risk thresholds that accounts for interaction of multiple uncertainty sources and an entire range of uncertainty.

Recommendation 8: Within 18 months of receipt of this report, the Federal Aviation Administration should create a documented protocol addressing how uncertainties associated with Transport Airplane Risk Assessment Methodology outputs should be accounted for in continued operational safety decision-making.

Suggested Citation:"6 Improvements for the Use of TARAM Outputs." National Academies of Sciences, Engineering, and Medicine. 2022. Evaluation of the Transport Airplane Risk Assessment Methodology. Washington, DC: The National Academies Press. doi: 10.17226/26519.
×

INCORPORATING RISK IMPORTANCE RANKING IN TARAM DECISION-MAKING GUIDANCE

Probabilistic risk assessment (PRA) conducted for other application domains such as nuclear power plants1 and space exploration2 incorporates risk importance measure analysis as one of the key methodological steps. The risk importance measure analysis can be considered as one type of sensitivity analysis, aimed at examining how risk outputs respond to changes in reliability condition of each risk element (e.g., systems, components, equipment, and human action). The results of risk importance measures can provide risk insights as to which risk elements are the critical risk contributors. The existing risk importance ranking methods used by PRA practitioners primarily focus on ranking cut sets, subsystems, and components/equipment based on their functional contribution to the system risk. If the scope of causal modeling in risk assessment is expanded, more in-depth risk insights can be extracted from the risk importance ranking. For instance, Groth et al. (2010) developed a three-layer hybrid causal logic modeling approach, where an event sequence diagram and fault trees at the subsystem- and component/equipment-levels are integrated with Bayesian Belief Networks (BBNs) to model the underlying causal factors.3 Their study also proposed an extended risk importance measure method to rank the underlying causal factors based on their contribution to aircraft risk. Research needs to be conducted to select the appropriate risk importance measure methodology for TARAM and the COS. The results of risk importance measure analysis can provide quantitative guidance for the identification and prioritization of corrective action alternatives in the COS decision-making.

Finding: Risk importance ranking is not incorporated into the TARAM decision-making guidance; hence, risk information is not fully utilized for the prioritization of options for corrective actions or as input to risk-informed inspections.

Recommendation 9: Within 12 months of receipt of this report, the Federal Aviation Administration should enhance the Transport Airplane Risk Assessment Methodology decision-making guidance by incorporating risk importance ranking methods to generate quantitative ranking measures for the prioritization of alternative corrective actions and risk-informed inspections.

IMPROVING THE QUALITY OF THE COS DECISION-MAKING PROCESS WHEN USING THE TARAM RESULTS

The regulatory decision-making for high-consequence industries needs to be “risk-informed.” The “risk-informed” approach combines risk information (e.g., calculated risk values) with other safety principles to reach a decision. The purpose is to ensure that adequate protection is maintained under the presence of uncertainties associated with the risk models and inputs. For instance, for commercial nuclear power plants, the U.S. Nuclear Regulatory Commission (U.S. NRC) has an integrated risk-informed regulatory framework, where risk information from PRA is used “in a manner that complements the U.S. NRC’s deterministic approach” including compliance with the existing regulations, defense-in-depth philosophy, sufficient safety margins, and performance monitoring.4 The risk-informed approach is used in every aspect of the U.S. NRC’s activities, and area-specific documentation is provided in various places. For example, the risk-informed decision-making framework for licensing basis change is documented in Regulatory Guide (RG) 1.174.5 As another example, a comprehensive description of the risk--

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1 U.S. Nuclear Regulatory Commission, 2020, Acceptability of Probabilistic Risk Assessment Results for Risk-Informed Activities, Regulatory Guide 1.200, Revision 3, Washington, DC.

2 National Aeronautics and Space Administration, 2011, Probabilistic Risk Assessment Procedures Guide for NASA Managers and Practitioners, NASA/SP-2011-3421, 2nd ed., Hanover, MD: NASA Center for AeroSpace Information.

3 K. Groth, C. Wang, and A. Mosleh, 2010, “Hybrid Causal Methodology and Software Platform for Probabilistic Risk Assessment and Safety Monitoring of Socio-Technical Systems,” Reliability Engineering & System Safety 95(12):1276–1285.

4 U.S. Nuclear Regulatory Commission, 1995, Use of Probabilistic Risk Assessment Methods in Nuclear Regulatory Activities; Final Policy Statement, Washington, DC.

5 U.S. Nuclear Regulatory Commission, 2018, Regulatory Guide 1.174 (Revision 3): An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis, Washington, DC.

Suggested Citation:"6 Improvements for the Use of TARAM Outputs." National Academies of Sciences, Engineering, and Medicine. 2022. Evaluation of the Transport Airplane Risk Assessment Methodology. Washington, DC: The National Academies Press. doi: 10.17226/26519.
×

informed, performance-based Reactor Oversight Process (ROP) is provided through the U.S. NRC’s website,6 where the detailed guidance documents on inspections, assessments, enforcement, and allegation are publicly available.

For the COS decision-making for transport airplanes, FAA Order 8110.107A clarifies that:

In rare situations, the ASE or FAA management may, based on factors unrelated to the risk analysis, make recommendations not consistent with risk guidelines for ADs or other mandatory corrective actions. The decision to accept or reject these recommendations is made during the CARB.

The Seattle ACO Transport Airplane Safety Manual provides detailed guidance as to how the quantitative risk results from TARAM should be combined with other safety considerations in the COS decision-making. Section 3 of the Seattle ACO Transport Airplane Safety Manual states that, in addition to the quantitative risk values computed by TARAM, the CARB decision as to whether a condition under study is unsafe should account for other criteria, including high-visibility events, lessons learned from the past accidents, impact of air traffic control on aircraft operations, risk to maintenance and operations personnel, fail-safe design, and qualitative safety criteria (e.g., design deficiency or manufacturing escape, single failure that could result in a catastrophic event, multiple failure with a preexisting latent failure). Meanwhile, the CARB decisions on urgency and priority of corrective actions for the unsafe conditions are solely based on two quantitative outputs from TARAM: (1) the 90-Day Fleet Risk (typically converted to the Priority Rating) and (2) the “Outer Marker Times” representing how long it takes until the control program risk guideline is reached if no corrective action is taken. No documentation is provided as to whether and how the other safety considerations could be factored into the CARB decision-making for urgency and priority of corrective actions.

Furthermore, no documentation is provided regarding when or how to aggregate risks from any other COS issues associated with an aircraft type for which a TARAM analysis is being conducted.

Finding: There is no explicit guidance or documentation in the TARAM Handbook regarding how the “factors unrelated to the risk analysis” are considered in the COS decision-making process by the FAA. The Seattle ACO Transport Airplane Safety Manual, based on which the COS decisions for Boeing in-production airplanes are made, has specific guidance as to how other safety considerations are incorporated when determining whether a condition under study is unsafe. However, the existing documentation does not provide any explicit guidance on how the quantitative TARAM risk outputs would be combined with other safety principles for determining the urgency and priority of the identified unsafe conditions and their corrective actions.

Recommendation 10: Within 6 months of receipt of this report, the Federal Aviation Administration should document as national guidance how Transport Airplane Risk Assessment Methodology results are to be integrated with other safety principles throughout the continued operational safety decision-making process.

As mentioned in Chapter 3, the FAA has recently updated two orders that address safety. FAA Order 8040.4B Safety Risk Management Policy explicitly defines steps of the agency’s Safety Risk Management (SRM) process and requires the use of a Hazard Identification, Risk Management, and Tracking (HIRMT) tool. Additionally, FAA Order 8000.369C, Safety Management System, refers to FAA Order 8040.4B and the HIRMT tool several times as the source for SRM guidance.

The committee assumes that these two orders are applicable to all FAA processes, including the processes described in the TARAM Handbook and FAA Order 8110.107A (MSAD). However, the concept of independent reviews, peer reviews, or audits of the TARAM and/or MSAD process is not addressed. This is a significant gap that would not be conducive to maximizing the quality of the FAA’s COS decision-making process when using TARAM results.

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6 U.S. Nuclear Regulatory Commission, Reactor Oversight Process (ROP), https://www.nrc.gov/reactors/operating/oversight.html, accessed June 4, 2022.

Suggested Citation:"6 Improvements for the Use of TARAM Outputs." National Academies of Sciences, Engineering, and Medicine. 2022. Evaluation of the Transport Airplane Risk Assessment Methodology. Washington, DC: The National Academies Press. doi: 10.17226/26519.
×

Specifically, page 4 of FAA Order 8040.4B on SRM states:

The regulator must also apply the controls that it is able to, and establish a methodology to monitor the safety risk. In general, FAA organizations that are regulators do not perform SRM on behalf of individual product/service providers. Rather, the product/service provider is responsible for conducting their own SRM. A regulator may conduct an independent assessment to validate a product/service provider’s assessment or, simply, to have an independent view of the issue/concern. Additionally, the FAA may need to facilitate SRM in situations where the safety risk owner is unable or unwilling to do so.

Additionally, paragraph 1d(i)(2) on page 11 of the order states:

Peer review is encouraged to strengthen decision maker confidence in the findings. Individuals, other than those who have conducted SRM, should perform the peer reviews. These individuals should have similar expertise as the SRM Team members. The FAA SMS Committee reviews safety risk assessments that it tracks and manages on behalf of the FAA SMS Executive Council.

Also, Chapter 3 of FAA Order 8000.369C addressing the SMS process of oversight, states:

Monitor, evaluate, or audit standards, systems, programs, and processes on a routine basis to determine the performance and effectiveness of safety risk controls both within the FAA and in aviation product/service provider organizations for which the FAA organization has oversight responsibility.

To support the quality of COS decision-making, a review process is required to continuously evaluate (1) the adequacy of the TARAM analysis to generate risk results and (2) the adequacy of the use of the TARAM results in the COS decision-making process. The review process could consist of multiple layers of reviews at different phases of the COS decisions involving various stakeholders to provide evaluations from diverse perspectives. However, the existing COS decision-making process and the TARAM process do not provide a documented independent review or quality assurance process.

Related to the first aspect of the independent review process that focuses on adequacy of the risk assessment process and its outputs, the risk analysis community recognizes the criticality of establishing a “pragmatic validity” of risk analysis, defined as “the condition where a risk assessment method meets its intended requirements in terms of the results obtained.”7 For instance, Suokas and Rouhiainen proposed to categorize approaches for assuring pragmatic validity of risk analysis into four groups8: (1) benchmark exercise, which compares the risk analysis results with a complete or partial parallel analysis of the same system; (2) reality check, which compares the risk analysis results with operational experience; (3) independent peer review, which examines the risk analysis output by an independent technical expert(s); and (4) quality assurance, which examines the process behind the analysis. The benchmark exercise is usually not recommended to be conducted for individual application cases because its intensive resource requirement is hard to justify. Rather, the benchmark exercise is typically conducted for a selected representative case study. Meanwhile, for the TARAM results, the reality check based on a comparison with operating experience is most often infeasible, especially (1) when the airplane design under study is relatively new and, thus, has limited operating experience; (2) when the condition of concern is rare and, therefore, its empirical data are sparse; or (3) when the control program risk after the corrective action implementation needs to be calculated in a predictive manner. To evaluate the pragmatic validity of the TARAM results, independent review and quality assurance processes could be conducted.

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7 F. Goerlandt, N. Khakzad, and G. Reniers, 2017, “Validity and Validation of Safety-Related Quantitative Risk Analysis: A Review,” Safety Science 99:127–139.

8 J. Suokas and V. Rouhiainen, 1989, “Quality Control in Safety and Risk Analyses,” Journal of Loss Prevention in the Process Industries 2(2):67–77.

Suggested Citation:"6 Improvements for the Use of TARAM Outputs." National Academies of Sciences, Engineering, and Medicine. 2022. Evaluation of the Transport Airplane Risk Assessment Methodology. Washington, DC: The National Academies Press. doi: 10.17226/26519.
×

Regarding the second aspect of the independent review process that focuses on the use of the risk assessment in the COS decision-making, the U.S. NRC’s ROP9 provides a good example of a multi-layer review structure for regulatory decisions.

  • At the level of each decision for a specific operational observation, after the enforcement panel of the U.S. NRC recommends enforcement action and considers risk information and other safety principles, the licensee has the opportunity to respond to the conference/choice letter or choice call to meet and discuss any new information and different views before the Agency’s final decision.10
  • The U.S. NRC implements the annual ROP Self-Assessment Program,11 where the U.S. NRC staff evaluates the performance of ROP based on multiple criteria, including performance metrics and data trending, program area evaluations, effectiveness reviews, and continuous baseline inspection program monitoring. The reports of the ROP annual self-assessments are available online.12
  • Aside from the annual ROP Self-Assessment Program, independent evaluations have been performed to analyze the performance of ROP or its specific sub-processes and recommend improvements. These independent evaluations were conducted by external organizations, including the Government Accountability Office, the Office of Management and Budget, the U.S. NRC Office of the Inspector General, the Advisory Committee for Reactor Safeguards, the Davis-Besse Lessons Learned Task Force, and the Significance Determination Process Task Group. The reports of the independent evaluations are available online.13

Leveraging the review framework for the ROP by the U.S. NRC, the COS decision-making process based on TARAM results could be reviewed in two phases. First, individual COS decisions could be reviewed before reaching the final decisions. If the review for all cases is not feasible, the review could be conducted under certain conditions that may significantly impact operational safety (e.g., if the estimated risk or the injury ratio is relatively high). Second, the use of TARAM results in COS decision-making could be evaluated periodically from the process perspective by assessing the effectiveness of the COS decisions in a retrospective manner (in a manner similar to the U.S. NRC’s annual Self-Assessment Program) and by requesting independent evaluations under specific situations, for instance, when an observed safety-related event indicates potential gaps in the TARAM analysis and its use in the COS decision-making.

Finding: There is no documented independent review process or quality assurance process to evaluate the adequacy of the TARAM results and the quality of COS decision-making based on the TARAM results.

Recommendation 11: Within 12 months of receipt of this report, the Federal Aviation Administration (FAA) should conduct and document a study to determine the requirements and viability of an independent peer review and quality assurance process for (1) the results from the Transport Airplane Risk Assessment Methodology (TARAM) analysis of significant in-service safety issues and (2) the continued operational safety (COS) decisions resulting from TARAM outputs. Details of the independent peer review and quality assurance process should be documented in the COS agreements between the manufacturers and the FAA.

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9 The U.S. NRC Reactor Oversight Process (ROP) collects information from operators of commercial nuclear power plants, assesses the information based on its operational safety significance, and provides appropriate regulatory responses (e.g., corrective actions and inspections); see https://www.nrc.gov/reactors/operating/oversight/rop-description.html, accessed June 4, 2022.

10 U.S. Nuclear Regulatory Commission, 2017, Nuclear Regulatory Commission Enforcement Manual, Revision 10, Change 1, Washington, DC: Office of Enforcement, https://www.nrc.gov/docs/ML1721/ML17212A125.pdf.

11 U.S. Nuclear Regulatory Commission, 2009, “Reactor Oversight Process Self-Assessment Program,” Manual Chapter 0307 in NRC Inspection Manual, Washington, DC.

12 See U.S. Nuclear Regulatory Commission, “Annual Self-Assessments,” https://www.nrc.gov/reactors/operating/oversight/programevaluations.html#section1, accessed June 4, 2022.

13 See U.S. Nuclear Regulatory Commission, “Independent Evaluations,” https://www.nrc.gov/reactors/operating/oversight/programevaluations.html#section2, accessed June 4, 2022.

Suggested Citation:"6 Improvements for the Use of TARAM Outputs." National Academies of Sciences, Engineering, and Medicine. 2022. Evaluation of the Transport Airplane Risk Assessment Methodology. Washington, DC: The National Academies Press. doi: 10.17226/26519.
×

Details of the COS agreements with the FAA were discussed earlier in Chapter 3 and in Recommendation 3 within that chapter.

As cited previously in this chapter, national guidance for TARAM is currently contained only in one published document—the TARAM Handbook—and also in its associated set of unpublished presentation slides that are intended to train FAA aviation safety engineers (ASEs) who perform or oversee risk analysis for transport airplanes as part of FAA Order 8110.107 MSAD process. The Seattle ACO also utilizes its own document for further guidance, but this guidance is not national policy or performed uniformly across other ACOs involved in transport airplane COS. The FAA currently has no formal training curriculum or recurrent training schedule for TARAM, and as mentioned in Chapter 3, the agency now has only one recognized subject-matter expert for TARAM, following the recent retirement of the ASE who first developed TARAM. This lack of robust expertise in this process within the FAA likely contributed to the inability to keep the handbook up to date, and also to ensure that sufficient training is provided to ASEs.

The benefits of establishing such a training program are obvious as demonstrated by similar programs established by the U.S. NRC and the National Aeronautics and Space Administration (NASA). A formal training regimen would ensure that engineers and middle level managers are aware of up-to-date probability risk assessment methods to better inform risk-informed decision-making for corrective action. Embarking on this initiative would also expedite the adoption and integration of this report’s recommendations.

Like the U.S. NRC and NASA, the FAA would also benefit from establishing a research group to keep the risk methodologies up to date. The U.S. NRC also has a very strong branch of research on PRA and risk-informed decision-making. The U.S. NRC risk group and managers have a periodic training on PRA. In fact, when NASA wanted to adopt U.S. NRC’s PRA, they initiated a similar path of training and research, benefiting from PRA experts from the U.S. NRC, academia, national laboratories, and industry.

Recommendation 12: Within 18 months of receipt of this report, the Federal Aviation Administration should develop and maintain a technical training program for aviation safety engineers and their management who conduct and review Transport Airplane Risk Assessment Methodology analysis. The training should include the concepts of probabilistic risk analysis and the use of risk assessment results in the continued operational safety (COS) decision-making, similar in scope to those used in other federal agencies, to ensure the assumptions and limitations of the probabilistic risk analysis techniques are applied to the COS of commercial airplane operations.

Recommendation 13: Within 6 months of receipt of this report, the Federal Aviation Administration should initiate research and continuous improvement programs in probabilistic risk analysis, including the use of risk assessment results in continued operational safety decision-making.

Several areas of improvement for TARAM, mentioned in this report, would benefit from this research initiative; for example, systematic risk modeling, dependency treatment, human reliability analysis, software reliability analysis, uncertainty analysis, importance measure ranking, and the incorporation of in-depth causal modeling (e.g., probabilistic physics-of-failure analysis and maintenance organizational performance analysis) into TARAM.

Suggested Citation:"6 Improvements for the Use of TARAM Outputs." National Academies of Sciences, Engineering, and Medicine. 2022. Evaluation of the Transport Airplane Risk Assessment Methodology. Washington, DC: The National Academies Press. doi: 10.17226/26519.
×
Page 40
Suggested Citation:"6 Improvements for the Use of TARAM Outputs." National Academies of Sciences, Engineering, and Medicine. 2022. Evaluation of the Transport Airplane Risk Assessment Methodology. Washington, DC: The National Academies Press. doi: 10.17226/26519.
×
Page 41
Suggested Citation:"6 Improvements for the Use of TARAM Outputs." National Academies of Sciences, Engineering, and Medicine. 2022. Evaluation of the Transport Airplane Risk Assessment Methodology. Washington, DC: The National Academies Press. doi: 10.17226/26519.
×
Page 42
Suggested Citation:"6 Improvements for the Use of TARAM Outputs." National Academies of Sciences, Engineering, and Medicine. 2022. Evaluation of the Transport Airplane Risk Assessment Methodology. Washington, DC: The National Academies Press. doi: 10.17226/26519.
×
Page 43
Suggested Citation:"6 Improvements for the Use of TARAM Outputs." National Academies of Sciences, Engineering, and Medicine. 2022. Evaluation of the Transport Airplane Risk Assessment Methodology. Washington, DC: The National Academies Press. doi: 10.17226/26519.
×
Page 44
Suggested Citation:"6 Improvements for the Use of TARAM Outputs." National Academies of Sciences, Engineering, and Medicine. 2022. Evaluation of the Transport Airplane Risk Assessment Methodology. Washington, DC: The National Academies Press. doi: 10.17226/26519.
×
Page 45
Suggested Citation:"6 Improvements for the Use of TARAM Outputs." National Academies of Sciences, Engineering, and Medicine. 2022. Evaluation of the Transport Airplane Risk Assessment Methodology. Washington, DC: The National Academies Press. doi: 10.17226/26519.
×
Page 46
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The Transport Airplane Risk Assessment Methodology (TARAM) is a process for calculating risk associated with continued operational safety issues in the U.S. transport airplane fleet. TARAM is important because its risk-analysis calculations are used when making determinations of unsafe conditions in transport airplanes and when selecting and implementing corrective actions. This report assesses the TARAM process used by the FAA in its efforts to improve the overall safety of the transport airplane fleet. A healthy safety culture requires commitment to continuous improvement. This report provides recommendations to the FAA to address the gaps and strengthen the TARAM.

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