Fault Tree Analysis (FTA)


Safety from Top to Bottom

Critical systems and products often have protection layers, fault tolerance and redundancies in order to prevent severe safety events. In order to calculate the occurrence probability of safety events, combinations of sub-events have to be accounted for.

BQR’s Fault Tree Analysis software provides quick and accurate analysis of complex scenarios, providing deep insight regarding drivers of safety events.



  • Reduce severe product failure events and increase mission reliability
  • Accurate and fast calculations

  • Use FMECA database for initial model

Special Offer

BQR’s FTA software is now available for only 99$ (annual subscription).


  • Cut-Set calculation
  • Common causes and nested common causes
  • Configurable Diagrams


Fault Tree Analysis software by BQR complies with IEC 61025 standard

FTA traditional view
FTA traditional view

How It Works

Steps for conducting analyses using BQR’s Fault Tree Analysis Software


  • Import the failure modes, effects, and ratios from BQR’s FMECA module using BQR’s Core Database

User Input

  • Define Mission Time
  • Add failure modes, failure rates, and effects (skip this step if initial data was imported)
  • Add additional external events such as harsh weather or human errors
  • Define gate types (logical relation between sub-events)
  • Define special mission time and common causes
Fault Tree Analysis software - screenshot
Logical Gates and Event Types


  • Probability analysis
  • Cut-Sets – minimal event combinations that cause the top event
  • Sensitivity analysis – identify key failure drivers


  • Probability analysis
  • Cut-Sets
  • Sensitivity analysis
  • All reports can be saved as Excel, HTML or Word files
Fault Tree Analysis software - screenshot 2
Informative Tree View

Fault Tree Analysis Software Features

  • Large variety of gate types: OR, AND, K out of N, Standby, AND Priority, NOT and XOR
  • Binary Decision Diagram (BDD) used for analysis of complex cases
  • Cut-sets analysis
  • Sensitivity analysis
  • Model various recovery types and Inspections