What is Fault Tree Analysis (FTA) and How to Do?

Last updated on August 23, 2021 by

As the name suggests, fault tree analysis is an analytical tool that represents the critical components to test the safety and reliability of a complex system. This is composed of a series of events in a top-down approach to assess probable failure consequences. Furthermore, it takes the concept of boolean logic where statements are based on True/ False depicting the path of failure. FTA is essentially is developed to identify potential failures and their causes in order to address the risk and be prevented. To understand FTA analysis further, read through the rest of the article.

Fault tree analysis

Fault Tree Analysis Symbols and Editable Examples

Importance of Fault Tree Analysis

As mentioned, the fault tree is a graphical tool that creates a record of a series of statements to define the probable failure consequences of a system. Thus, it is popular in the fields of engineering. It permits the managers to see a component that may cause many paths to failures. Through fault tree analysis, managers will be able to focus on the area of the fault and address the issue prior to the launch or execution. In other words, it lets you highlight the critical elements related to system failure and produce a reliable and safe system. It does not only

FTA Analysis Symbols

Just like any diagram, there are symbols that make up a fault tree. Also, each symbol denotes a unique function to show the logical arrangement of events and understand the system well. Basically, there are two types of notation for the fault tree diagram. This includes events and logic gates. So to assist you in designing this diagram, here are the following symbols and their description you should know about.

fault tree diagram symbols

Basic event– a basic failure event which represents by the circle

External event– an event that represents occurrence and non-occurrence

Undeveloped event– events that are under development and do not require further resolution

Conditioning event– an event that is used to associate with other events to indicate condition or restriction

AND gate– this symbol implies that all input conditions are met

OR gate– an output event is a fault tree diagram which at least one condition is met

Priority AND gate– this occurs when all input events occur in order or specific sequence

Exclusive OR gate– appears if there’s only one condition that takes place

Inhibit gate– takes place when the input condition is met along with the associated condition

How to make Fault Tree Analysis

In this section, you will learn how to create a fault tree with simple steps. But before that, you need to decide whether you want to create using a pen and paper or a fault tree analysis program. Of course, a program made to create such diagrams would make things a lot easier. In fact, there are countless diagramming tools. Yet for free and fully-featured software, GitMind is the best of the bunch. It provides shapes and figures you need to create diagrams and flowcharts. Also, you don’t need to install and you can even use it on your smartphone provided you have a browser and internet connection. Below is the guide to draw a fault tree diagram.

  • Go to the official website of GitMind using any browser. Once landed on the page, click “Get Started” followed by the “New Flowchart” button.
flowchart function button
  • Then it will direct you to the editing interface. At first, add the shapes you need by clicking the “More Shapes” at the bottom left-hand interface.
  • Now unfold the folder that contains the figures needed and then start by identifying the undesired event of the system. Input the corresponding shapes until you form a fault tree model.
FTA analysis shapes
  • At this point, you should be able to draw a fault tree diagram. Once satisfied, you may keep the diagram private or share the diagram as it is via the share link.
share link diagram

Or you can get its desktop version from the download link below:


Examples of Fault Tree Analysis

If you need further understanding of this diagram, you can refer to the examples below. Here you will find some simple examples to grasp the idea behind FTA.

Figure 1: Fault tree of a computer not starting

fault tree diagram
Edit this example

This is a simple example of a fault tree. It identifies the probable causes of why a computer is not starting or turning on. From the fault tree analysis, you will see an OR gate which shows the causes of the primary fault. It could be “No power” or “Booting Problem”. As you dig way deeper, you will be able to define the most basic causes of the problem.

Figure 2: Fault tree of application crash

fault tree analysis
Edit this example

Proving the flexibility of a fault tree, it is not only used for hardware systems but also in software development as shown in the example give. This particular example gives the reader the probable causes for the application crash. Causes include problems scalability if there are many users or congested with people. Then under these causes are basic events that contribute to the primary fault event creating a fault tree diagram.


One system may fail one way or another as the development of technology becomes more complex. Through FTA, you can create a safe and reliable system by identifying the probable hazard in a system. After obtaining knowledge about FTA and some examples, you will be able to create your own FTA to help you when designing or updating a system.

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Posted by: on to Tips and Resources. Last updated on August 23, 2021

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  • The templates are highly-recommended! I think providing them are a great help, and you did well in explaining this complicated topic as simple as possible. Good job!