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5 Whys methodology in ICARUS

One of the easiest and most used methodology to find the root cause is famous 5 Why’s. We take a deeper look at 5 Why’s and how it is implemented in ICARUS software for aviation safety and quality management system.


5 Why’s or 5Y is an iterative or repetitive method to discover the root cause of a particular issue. By repeating the question “Why” for each answer, the method provides a way to find a root cause. Each answer provides a basis for a subsequent “Why” question.


The method has been developed in 1930s by Japanese inventor and industrialist named Sakichi Toyoda. The method became an integral part of the Toyota Motor Corporation, a famous Japanese multinational automotive manufacturer. The architect of Toyota Production System, Taiichi Ohno, quoted: “The basis of Toyota’s scientific approach is to ask why five times whenever we find a problem … By repeating why five times, the nature of the problem as well as its solution becomes clear.” Aviation as other industries have adopted this method as one of the widely used methods in determining root cause.


Benefits of 5 Why’s method are: effective method to discover the root cause of the problem, recognize how one hazard can cause the chain reaction and simple to understand tool.


The drawbacks are few, but the most obvious one is that it can determine only one root cause thus making it not suitable for complex problem-solving.


5 Why’s is an easy and effective tool and can be used in simple to moderate problem-solving situations. It is recommended to use it also as part of your training processes in order to develop analytical thinking.


When defining the root cause of a certain issue, you need to gather a team who are familiar with the domain of the problem. Once the team is gathered, you define the problem that has occurred, for example “Reporting is below our safety performance indicator target”, “Department X is not responding to findings on time” or it can be a certain event such as “Aircraft X tires burst on landing at Y airport”.

You begin by asking the first “Why” question. For example “Why problem X occurred?”. The answer will give you the basis for the following question. For example if the answer to a question “Report is below our targets” is “Because the employees are not using reporting platform”, then the next “Why” question would be: “Why the employees are not using the reporting platform?” etc. By digging deeper into the issue, this method will help to determine the real or root cause of the problem.

The recommended number of “Why” questions is 5, but it can vary depending on the problem.


Our development team integrated the method as part of the “Risk Management” module where our customers can easily determine the root cause of a hazard or a finding they are analyzing. The ICARUS implementation of 5 Whys method is simple and user-friendly. All the users of ICARUS software have to do is to create answers for each “Why” question to determine the final root cause. Once root cause is determined, ICARUS software solution provides the corrective actions feature with automatic notifications to all responsible persons. Of course, ICARUS also notifies the results back to the team.

ICARUS simplified 5 Whys method


In our experience, the best way to learn is through examples and here we provide to our readers a little example.

Lets take an event that one of the aircraft in our fleet has landed on one airport and suffered burst tires which caused damage to our aircraft.

We define the problem: “An aircraft X was damaged on landing at Y airport”

Now we can start using our 5 Why methodology to determine the root cause of the problem. We begin with the first “Why question”.

  1. Why the aircraft is damaged?
    Our team finds the answer which was obvious: “Because the tires burst and damaged part of the aircraft with debris“.
    This provides the basis for the next question.
  2. Why the tires burst?
    This makes it a bit more difficult to answer and our team has to dig deeper into the issue. Once the information has been collected, we found out that it was “because there was too much pressure in the tires“.
    Again this answer provides the basis for the next question.
  3. Why there was too much pressure in the tires?
    Now the team investigates more and finds out that “there was a faulty reading on one of the instruments in the previous aircraft check“.
    Now, we can form another question.
  4. Why there was a faulty reading?
    Easily, our team finds out staggering discovery that “because the instrument was not tested“.
    We can now form our last question on the basis of that answer.
  5. Why the instrument was not tested?
    Here, the final root cause we determined was “because the instrument was not in the maintenance schedule or in better words that it wasn’t calibrated“.

Using our 5 Why method we determined the final root cause and now we can construct our corrective action plan to minimize the risk of such scenario occurring again.


About the author

Inxelo Technologies

Inxelo Technologies Ltd. is a company that core-business is software development in aviation industry.
Our mission is to provide quality software solutions to any air operator and improve their operations.
The software solutions we create for our customers are in various fields in aviation such as safety management system and compliance management system.