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SIRA Methodology in ICARUS

We are happy to publish that SIRA (Safety Issue Risk Assessment) framework has been integrated in ICARUS SMS QMS software solution for our customers continuing our progress of simplifying and enhancing Risk Management module.


An industry working group, ARMS (Aviation Risk Management Solutions) was set up in 2007 in order to develop a new and better methodology for Operational Risk Assessment (ORA). The primary target group for the methodology is airlines but it was aimed also to be fully applicable to other aviation organizations. One of the methods developed by ARMS was Safety Issue Risk Assessment (SIRA). SIRA is a risk assessment tool for safety issues that are identified after the data analysis of events by taking into account four factors instead of classic severity x likelihood formula.

As a result of data analysis, the organization will gradually identify a number of Safety Issues affecting its operation. Here comes SIRA where those risks can be assessed using this approach. Our customers now can use SIRA through software ICARUS for managing safety and quality management system.


One of the major limitations of the classic severity x likelihood formula is that it does not support taking into account the barriers (i.e. the Risk Controls). Typically, the analyst needs to first assess the risk considering current barriers (without any specific way to quantify their effectiveness) and then make another assessment, considering new additional barriers.

SIRA provides an improved formula for the risk estimation that is based on four factors instead of the classic severity x likelihood formula. Those four factors are:

  • Frequency/probability of the so-called Triggering Event
  • Effectiveness of the Avoidance Barriers
  • Effectiveness of the Recovery Barriers
  • Severity of the (most probable) accident outcome

SIRA framework four factors

SIRA framework is displayed on the figure above. The first step is to define Safety Issue properly (title, descriptions of hazard(s), description of related accident scenario(s), time under study etc.). Once the Safety Issue has been defined, the analyst has to create the applicable accident scenario(s). These scenarios can then be risk assessed using SIRA. Typically, the highest risk produced by a scenario becomes the Safety Issue risk value.

After finding the Safety Issue risk value, we need to find the UOS. The Undesirable Operational State (UOS) is defined by ARMS as: “The stage in an accident scenario where the scenario has escalated so far that (excluding providence) the accident can be avoided only through successful recovery measure(s). Risk Controls prior to the UOS are part of Avoidance and post-UOS are part of Recovery.

For example, the UOS could be “ending up on a collision course with another aircraft”. A recovery measure would then be, for example, a TCAS alert combined with the correct pilot (or aircraft) reaction.

After the UOS has been defined, we can find the accident outcome scenarios. SIRA has similarities with Bow-Tie as both also require defining barriers – avoidance and recovery barriers.

ICARUS screenshot demonstrating SIRA methodology feature including four factors in the risk assessment

Once everything is set up, we can proceed with the formula. First factor is “Frequency/probability of the so-called Triggering Event” or the estimated frequency of the triggering event (per flight sectors). The second and third factors in the SIRA formula are estimates about the effectiveness of the avoidance and recovery barriers. Finally, the fourth factor is the severity of the accident outcome, in line with the ERC vertical scale.

In effect, the first three factors commonly define the “mean frequency of the accident due to this Safety Issue” while the last factor indicates the severity of the accident. To build a proper methodology, it is necessary to decide which combinations of frequency and severity are tolerable. JAR/FAR-1309 tolerability limits for aircraft design is one source for such limits.



JAR/FAR-1309 limits are used to produce the output result on a scale of five levels of risk:

Unacceptable levels of risk:
• Stop
• Improve

Tolerable levels of risk:
• Secure
• Monitor
• Accept

The exact meaning for each of the results has to be defined at the company level. Here is an example of what the results could mean:

  • Stop: the concerned part of the operation (e.g. destination, aircraft type, procedure) has to be discontinued immediately until an acceptable risk
    reduction measure has been implemented. The matter receives immediate top management attention.
  • Improve: Issue has to be raised and actioned at the Safety Action Group (SAG) and monitored at the Safety Review Board. Risk reduction measures need to be identified and started within an agreed time frame.
  • Secure: The risk level and its trend needs to be monitored continuously (at least at SAG level) in order to prevent escalation to unacceptable level. Reinforcement of existing measures should be discussed at the next convenient opportunity (e.g. at next scheduled SAG meeting) and taking further reduction measures should be considered.
  • Monitor: The Issue is followed regularly through the routine practice of database analysis and the monitoring of SIRA values for all Safety Issues in the Risk Register, i.e. it stays in the list of current or anticipated Safety Issues.
  • Accept: No specific action is required since the risk is well within the acceptable level.


ICARUS software has successfully integrated famous SIRA methodology in aviation. Now, ICARUS customers can collect Safety Issues and calculate the severity of the scenarios using such approach in an intuitive and user-friendly way inside the Risk Management module in ICARUS.

If you would like to find more about how SIRA is developed in ICARUS, contact us at:


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.