Evaluation of the Transport Airplane Risk Assessment Methodology (2022) / Chapter Skim
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2 Overview of TARAM
2 Overview of TARAM
Pages 10-18
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From page 10... ...
The MSAD process requires FAA aviation safety engineers (ASEs) to filter, review, analyze, and trend aviation safety data in order to identify safety issues that occur in the in-service aircraft fleets, and, more importantly, identify corrective actions to mitigate safety risks across the fleet.
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From page 11... ...
If urgent action is not required but the necessity for further investigation is indicated, the FAA will pursue a formal, more quantitative risk assessment via the TARAM, based on potential hazards, fleet age, fleet utilization, statistical distribution of failures, and historic outcomes. The TARAM results are used to support two layers of decision-making in the MSAD process: (1)
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From page 12... ...
Guidance for TARAM is contained in two formal FAA documents: the TARAM Handbook issued in 2011, and the Seattle ACO Transport Airplane Safety Manual issued in 2021. These documents, and their associated set of training slides, are intended to guide FAA ASEs who may perform or oversee risk analysis for transport airplanes as part of the MSAD process cited in FAA Order 8110.107.
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From page 13... ...
Unlike the initially calculated fleet risk that represents the expected number of events that will result in fatalities during the remaining lifetime of the fleet, the 90-day and the control program fleet risks now quantify the expected number of fatalities resulting from such events during the 90-day or the prescribed control program periods of time, respectively. Figure 2.2 provides a simplified flowchart of the current TARAM process to calculate these risk measures.
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From page 14... ...
NOTE: CARB: Corrective Action Review Board, MSAD: Monitor Safety/Analyze Data. SOURCE: FAA TARAM Handbook.
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From page 15... ...
Underlying data may be made available to the FAA depending on approval holder documentation practices, and this will be at the discretion of the design approval holder. The FAA TARAM policy states: "Affected design-approval holders should know, in general, the data and information that could be requested from them when aircraft certification offices are analyzing the risk associated with continued-operational-safety issues."10 Historical injury ratios11 for a variety of conditions and outcomes used for injury ratio calculations are from a data set developed by the FAA Aircraft Certification Service utilizing the NTSB Aviation Accident and the FAA AIDS.12 Current TARAM does not adequately characterize the uncertainty associated with the TARAM input data.
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From page 16... ...
The handbook further indicates that the guidance is based on the average risk of individual fatal injury per flight hour, experienced by passengers on transport airplanes operated within the United States, which is on the order of 10–8/flight hour. It also states: "Current uncorrected fleet risk guideline is a very general estimate of safety during this period." The TARAM Handbook has not been updated in the past decade to reflect the current state of the commercial airplane design and operations, and engineering justifications for current risk thresholds identified in TARAM risk guidance table.
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From page 17... ...
The TARAM Handbook does not provide guidance with regard to FAA decision-making for corrective action, except very generally in the preface. The Seattle ACO Transport Airplane Safety Manual provides additional guidance on the consideration of the "other criteria" in the COS decision-making in addition to the TARAM risk values.
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From page 18... ...
and CARB judgment will determine the urgency and priority for each issue that CARB determines requires corrective action," there is no further explanation, and in the current COS decision-making practice, the AD prioritization and the determination of control program times are solely based on the 90-day fleet risk and the Outer Marker Times14 that are computed using TARAM. With regard to the consideration of uncertainty, the TARAM Handbook, Seattle ACO Transport Airplane Safety Manual, and training materials are mostly silent.
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