HCRQ, INC. SYSTEM & SOFTWARE SAFETY EXPERTS
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  • Home
  • Markets
    • Aviation
    • Defense
    • Unmanned Systems
    • Rail Transportation
    • Process
    • Automotive
    • Nuclear
    • Medical
  • System/Software Safety Services
    • Consulting >
      • System Safety
      • Software Safety
      • Reliability, Availability, Maintainability
      • Quality Assurance / Quality Control
      • Full List of Consulting Services
    • Training >
      • Courses >
        • System Safety Course
        • Software Safety Course
        • MIL-STD-882E System Safety Course
        • Aviation System Safety Course
        • Hands-On Fault Tree Analysis Course
      • Webinars >
        • System Safety Webinars >
          • System & Software Safety: If You Were Us, What Would You Watch Out For?
          • System Safety Management Plans (SSMPs)
          • System Safety Program Plans (SSPPs)
          • Preliminary Hazard Analysis & Hazard Tracking
          • Operating & Support Hazard Analysis
          • Safety Assessment Report
          • Estimating Probabilities of Human Failures
        • Software Safety Webinars >
          • Software Safety Program Plans (SwSPPs)
          • Software FTA & Software FMEA
        • Other Webinars >
          • How To Get Promoted
        • Webinar FAQs
      • Renowned Attendees
      • Previous Course Attendees
    • Products >
      • Fault Tree Analyses - When to Accept, When to Reject
      • System Safety Program Plan (SSPP) Example
  • Scheduled Courses & Webinars
    • Scheduled Courses
    • Scheduled Webinars
  • Proposal & Technical Writing
    • Proposal Writing
    • Technical Writing
  • About Us
    • Who We Are
    • Hunter Austegard
    • China Austegard
    • Applicable Codes
    • Client List
    • Testimonials - Courseware
    • Testimonials - Consulting
    • Referral Fees
    • Newsletters
    • Reference Material
    • Careers
    • Contact Us
HCRQ, INC. SYSTEM & SOFTWARE SAFETY EXPERTS

FAULT TREE ANALYSIS (FTA)


The Fault Tree Analysis (FTA) technique was developed by H.R. Watson of Bell Telephone Laboratories in 1962.  Fault Tree Analysis was first applied to anti-ballistic systems.  Boeing further developed and refined the process becoming the foremost proponents of the method.

It is an accepted technique used to analyze system safety.  Not only is 
Fault Tree Analysis used for safety-critical systems analysis but also for mission-critical systems analysis.  Hardware, software and human factors can be analyzed in an integrated fashion.  Fault Tree Analysis is particularly suited to the analysis of complex systems consisting of several functionally related or dependent subsystems with different performance objectives.  This is especially true whenever the system design requires the collaboration of many specialized technical design groups.

A fault tree is a symbolic logic diagram, in the form of an inverted tree, showing the cause and effect relationship between an undesired event and contributing causes.  Fault trees clearly show the parallel and sequential combinations of events that can constitute a hazard.  
Fault Tree Analysis always begins assuming that an undesired event has taken place.  It is a backward moving process which attempts to determine all possible causes for the undesired event to occur.

Fault Tree Analysis can imply different things to different people as reflected by the wide range of depths of analysis that exist.  Coverage in the areas of:

  • fault tree verification,
  • minimal cut set analysis,
  • Common Mode Analysis (CMA),
  • importance analysis, and
  • supporting material

varies dramatically as does fault tree quality.  There truly are some scary FTA's out there.  A military client of ours showed us a SAR produced by a well-known defense company.  We noticed a problem with the top event of the tree!

What criteria should be applied to determine whether to accept or reject fault tree analyses?  There are 28 attributes (recently updated) to look for.  In a recent survey most fault tree analysts did not come close to answering this question.  If you work for government branches (e.g., FAA, FDA, FRA, DOD, and MOD), clients, auditors, or system integrators, and are a reviewer of contract deliverables, you should know this.  For additional information, click here. 
​
​HCRQ has over 33 years of experience in Fault Tree Analysis.

*** We
 can teach you how to perform one the proper way***
Our 2-Day Hands-On CAFTA Fault Tree Analysis Course is famous.


We are frequently hired to critique other's fault tree analyses.

By the way, do you know the disadvantages of using 
Fault Tree Analysis?
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