Fault Tree Analysis (FTA) for Safety-Critical Systems

Critical Systems Analysis
Critical Systems Analysis
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"Fault Tree Analysis (FTA) for Safety-Critical Systems" is a serial video course from CSA, published weekly in strict curriculum order — building from foundational terms and structure through lifecycle practice to advanced, assessor-level topics. Designed for working functional-safety engineers and managers, not beginners or students. CSA is a functional safety, reliability, and certification consultancy serving robotics, autonomous systems, transportation, and industrial equipment manufacturers. CSA provides end-to-end safety engineering services: preliminary gap analyses and safety audits, SIL/PL determination, FMEA and FMEDA execution, fault tree analysis, safety case development, hardware metrics (SPFM/LFM/PMHF), lifecycle documentation, and embedded safety engineering support. CSA engineers work alongside product teams from architecture through final functional safety assessment, and support companies seeking NRTL, CE, ATEX, ISO 26262, and UL 4600 marks. Contact: Sales@criticalsa.com. This series is part of the CSA Functional Safety Network — a coordinated set of weekly video courses covering IEC 61508, ISO 26262, ISO/SAE 21434, SOTIF (ISO 21448), UL 4600, IEC 62443, ISO/PAS 8800, ISO 13849, machinery safety, safety analysis methods, and more. Each show links to the others so practitioners can follow the thread that matches their project.

Episodes

  1. Aug 22

    Building Your First Fault Tree, Step by Step

    Fault Tree Analysis, or FTA, is a systematic, top-down method for identifying failures in complex systems. It begins with a single undesired event at the top—often called the top-level event—and works downward to discover all root causes using logic gates like AND and OR. Part of the Critical Systems Analysis functional-safety series on Fault Tree Analysis. In this episode: Welcome to this functional-safety micro-lecture on Fault Tree Analysis.Fault Tree Analysis is a deductive reasoning technique used to understand how combinations of failures lead to a top-level undesired event.Fault Tree Analysis serves multiple purposes in functional safety: it helps you understand system failures, identify critical weak points, and prioritize risk reduction efforts.Building a fault tree follows a logical progression.Every fault tree uses four key elements.Logic gates determine how lower-level failures combine to cause an upper-level event.Reference: Top event definition per IEC 61025:2006, section 5.2: undesired event or condition at system level that serves as the starting point for backward analysis. More in this series: Fault Tree Analysis (FTA) for Safety-Critical Systems | HARA, FMEA, FMEDA and TARA — Safety Analysis Explore more from Critical Systems Analysis. Partner with usFollow on LinkedInVisit our websiteRead our feature on Automate.orgAll shows on Apple Podcasts: AI & ML Safety | Fault Tree Analysis | FS Assessment | Safety Analysis | IEC 61508 | IEC 62443 | ISO 10218 | ISO 12100 | ISO 13849 | ISO 26262 | ISO/PAS 8800 | ISO 26262-11 | V-Model | UL 4600.

    Building Your First Fault Tree, Step by Step

  2. Aug 22

    Fault Tree Analysis (FTA) for Safety-Critical Systems

    Fault Tree Analysis is a top-down analytical method used in functional safety to identify and evaluate failure modes in safety-critical systems. Starting from an undesired top event, F-T-A maps all possible combinations of lower-level failures that could cause it. Part of the Critical Systems Analysis functional-safety series on Fault Tree Analysis. In this episode: Fault Tree Analysis, or F-T-A, is a systematic, deductive method for understanding how system failures develop.At its core, Fault Tree Analysis is a logic-based graphical representation of failure modes.Every fault tree consists of fundamental elements: a top event representing the undesired outcome, intermediate events showing failure combinations, basic events at the root, and logic gates defining how events combine.Logic gates determine how lower-level failures combine to cause higher-level events.The Fault Tree Analysis process follows a structured sequence starting with defining the top event.Fault Tree Analysis can be performed at two distinct levels of rigor.Reference: IEC 61508-5:2019 Section 7.4.7 defines FTA as a 'systematic, auditable and structured technique for the systematic identification of failures and their causes for the item under co More in this series: IEC 62443 — Industrial Cybersecurity Explore more from Critical Systems Analysis. Partner with usFollow on LinkedInVisit our websiteRead our feature on Automate.orgAll shows on Apple Podcasts: AI & ML Safety | Fault Tree Analysis | FS Assessment | Safety Analysis | IEC 61508 | IEC 62443 | ISO 10218 | ISO 12100 | ISO 13849 | ISO 26262 | ISO/PAS 8800 | ISO 26262-11 | V-Model | UL 4600.

    Fault Tree Analysis (FTA) for Safety-Critical Systems

  3. Aug 22

    What Is Fault Tree Analysis in Safety?

    This micro-lecture introduces Fault Tree Analysis, the systematic method standardized in IEC 61025 for analyzing system failures. Fault Tree Analysis works deductively: it starts with an undesired outcome—the top event—and traces backward through all possible combinations of faults that could cause it. Part of the Critical Systems Analysis functional-safety series on Fault Tree Analysis (IEC 61025). In this episode: This episode covers Fault Tree Analysis, standardized in IEC 61025, a foundational method for safety-critical system design.Fault Tree Analysis is a systematic, deductive approach to safety analysis.Fault Tree Analysis has several defining characteristics that make it powerful for safety work.Fault trees rely on four main logic gates to model how failures combine.The F T A process follows a systematic flow from abstract to concrete.The top event sits at the apex of your entire fault tree.Reference: Five-step methodology cited from IEC 61025:2006 Fault Tree Analysis standard: define top event, obtain system understanding, construct fault tree, evaluate fault tree, control haza More in this series: IEC 61508 — Functional Safety Foundations | Functional Safety Assessment and Services Explore more from Critical Systems Analysis. Partner with usFollow on LinkedInVisit our websiteRead our feature on Automate.orgAll shows on Apple Podcasts: AI & ML Safety | Fault Tree Analysis | FS Assessment | Safety Analysis | IEC 61508 | IEC 62443 | ISO 10218 | ISO 12100 | ISO 13849 | ISO 26262 | ISO/PAS 8800 | ISO 26262-11 | V-Model | UL 4600.

    What Is Fault Tree Analysis in Safety?

  4. Aug 22

    FTA vs FMEA: When to Use Which

    Fault Tree Analysis and Failure Mode and Effects Analysis are two foundational methods in functional safety engineering, but they work in opposite directions. Fault Tree Analysis, standardized in IEC 61025, is deductive—you start with a critical system failure and trace backward through all possible combinations of events that could cause it. Part of the Critical Systems Analysis functional-safety series on Fault Tree Analysis. In this episode: Fault Tree Analysis and Failure Mode and Effects Analysis are two essential reliability engineering methods that help identify how systems can fail.Fault Tree Analysis, standardized in IEC 61025, is a structured method for identifying all possible combinations of events that could lead to a specific undesired top event.Failure Mode and Effects Analysis, governed by IEC 60812, systematically examines each component or subsystem to identify all ways it could fail.These methods work in opposite directions and excel in different contexts.Fault Tree Analysis is your best choice when you have a specific critical failure you want to understand and prevent.Reference: ISO 26262-9 (Automotive Electrical/Electronic Functional Safety): Requires failure mode analysis in the design phase; Fault Tree Analysis appears in qualitative risk assessment sec More in this series: ISO 26262 — Automotive Functional Safety | Semiconductor Functional Safety (ISO 26262-11) Explore more from Critical Systems Analysis. Work with us | LinkedIn | criticalsystemsanalysis.com All shows on Apple Podcasts: AI & ML Safety | Fault Tree Analysis | FS Assessment | Safety Analysis | IEC 61508 | IEC 62443 | ISO 10218 | ISO 12100 | ISO 13849 | ISO 26262 | ISO/PAS 8800 | ISO 26262-11 | V-Model | UL 4600.

    FTA vs FMEA: When to Use Which

  5. Aug 22

    Using FTA to Verify Safety Goals

    Safety goals define the maximum risk your system can tolerate—but stating a goal and achieving it are different challenges. Fault Tree Analysis, or F T A, is the systematic method that bridges that gap. By starting with a potential hazard and working backward through all possible failure combinations, F T A reveals whether your design architecture actually prevents the failures that matter most. Part of the Critical Systems Analysis functional-safety series on Fault Tree Analysis. In this episode: Fault Tree Analysis, or F T A, is a systematic method for identifying how multiple failures combine to create unsafe conditions.F T A works backward from a potential hazard—called the top event—to discover all the sequences of failures that could cause it.Every F T A contains three types of events arranged hierarchically.Your safety goals define the maximum allowable risk.Start by defining your top event as precisely as possible.A minimal cut set is the smallest group of failures that, if they all occur, will cause the top event.Reference: Top event per IEC 61025 Section 3.1: The undesired outcome or fault condition analyzed. In safety applications, it represents the negation of the safety goal as required in ISO 262 More in this series: Fault Tree Analysis (FTA) for Safety-Critical Systems | HARA, FMEA, FMEDA and TARA — Safety Analysis Explore more from Critical Systems Analysis. Work with us | LinkedIn | criticalsystemsanalysis.com All shows on Apple Podcasts: AI & ML Safety | Fault Tree Analysis | FS Assessment | Safety Analysis | IEC 61508 | IEC 62443 | ISO 10218 | ISO 12100 | ISO 13849 | ISO 26262 | ISO/PAS 8800 | ISO 26262-11 | V-Model | UL 4600.

    Using FTA to Verify Safety Goals

  6. Aug 22

    Quantitative FTA: Cut Sets and Probabilities

    Welcome to quantitative Fault Tree Analysis. You've learned how to draw the tree—the gates, the failures, the paths to disaster. Now we turn that logic into numbers. Fault Tree Analysis by IEC 61025 is more than a cartoon of what can go wrong. It's a systematic framework for computing the probability that your system will fail. Part of the Critical Systems Analysis functional-safety series on Fault Tree Analysis. In this episode: In this episode, we explore how to convert qualitative F-T-A—our tree of failures—into actionable probability.A cut set is any combination of basic events whose simultaneous occurrence causes the top event.Compare two system designs.We start with gate logic—the A-N-D and O-R operators that combine our basic events.Fault tree gates are Boolean expressions.Once we have minimal cut sets, we assign failure rates to each basic event.Reference: Cut sets are defined per IEC 61025 Fault Tree Analysis and ISO 13849-1 Safety of machinery: minimal cut sets represent the smallest combinations of basic events sufficient to cause More in this series: Fault Tree Analysis (FTA) for Safety-Critical Systems | HARA, FMEA, FMEDA and TARA — Safety Analysis Explore more from Critical Systems Analysis. Partner with usFollow on LinkedInVisit our websiteRead our feature on Automate.orgAll shows on Apple Podcasts: AI & ML Safety | Fault Tree Analysis | FS Assessment | Safety Analysis | IEC 61508 | IEC 62443 | ISO 10218 | ISO 12100 | ISO 13849 | ISO 26262 | ISO/PAS 8800 | ISO 26262-11 | V-Model | UL 4600.

    Quantitative FTA: Cut Sets and Probabilities
  • 6 Episodes

About

"Fault Tree Analysis (FTA) for Safety-Critical Systems" is a serial video course from CSA, published weekly in strict curriculum order — building from foundational terms and structure through lifecycle practice to advanced, assessor-level topics. Designed for working functional-safety engineers and managers, not beginners or students. CSA is a functional safety, reliability, and certification consultancy serving robotics, autonomous systems, transportation, and industrial equipment manufacturers. CSA provides end-to-end safety engineering services: preliminary gap analyses and safety audits, SIL/PL determination, FMEA and FMEDA execution, fault tree analysis, safety case development, hardware metrics (SPFM/LFM/PMHF), lifecycle documentation, and embedded safety engineering support. CSA engineers work alongside product teams from architecture through final functional safety assessment, and support companies seeking NRTL, CE, ATEX, ISO 26262, and UL 4600 marks. Contact: Sales@criticalsa.com. This series is part of the CSA Functional Safety Network — a coordinated set of weekly video courses covering IEC 61508, ISO 26262, ISO/SAE 21434, SOTIF (ISO 21448), UL 4600, IEC 62443, ISO/PAS 8800, ISO 13849, machinery safety, safety analysis methods, and more. Each show links to the others so practitioners can follow the thread that matches their project.

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