AltaRica Association logo The AltaRica Association

an Open-PSA Fault Tree engine

XFTA: an efficient calculation engine

XFTA is a Fault Tree assessment engine working on models written at the Open-PSA model exchange format (the reference document is downloadable from the Open-PSA website). XFTA is a fully portable software that runs under Windows and Linux.

XFTA version 1.1 implements an efficient algorithm to compute Minimal Cutsets. This algorithm is original and works for both coherent and non-coherent models. XFTA implements also probabilistic assessments:

  • Calculation of the Top Event probability for different mission times.
  • Calculation of Importance Factors for Basic Events (Birnbaum/Marginal Importance Factor, Critical Importance Factor, Diagnosis Importance Factor, Risk Reduction Worth, Risk Achievement Worth).
  • Sensitivity Analyses by means of Monte-Carlo simulation.
  • Calculation of Safety Integrity Levels for low demand mode and high/continuous demand mode safety related system as required by Safety Standard IEC 61508 and daughters.

Calculation of Safety Integrity Levels requires the calculation of system availability, average availability, system failure intensity, approximation of system reliability, probability of failure on demand, probability of failure per hour…

To know more about XFTA features, download the XFTA Manual.

XFTA: a free calculation engine

XFTA is provided free of charge. Even though a license fee is not paid for the use of XFTA, it does not mean that there are no conditions for using it. Before you download the software, please read carefully the License Agreement.


Downloading the software means you accept with no restriction the terms of the License Agreement.

It may be also useful to have a look at: