Usability in Safety Critical Design

Usability in Safety Critical Design

What is it?

Usability in safety critical design refers to the design and development of modern user interfaces within safety critical industries such as transportation and defence. As industries implement modern technologies in all aspects of their operations, usability and user interface design become even more critical to system performance and safety.

SYSTRA combines Human Factors design and assurance methods with User Experience (UX) and User Interface (UI) design for safety critical systems. This unique blend of expertise enables us to optimise efficiency and task performance, whilst providing robust human factors and safety assurance at all stages of software development.

Why is important?

UX and UI design is a critical component in overall system safety. This is clearly demonstrated with examples of poor human machine interfaces that have resulted in disaster. In the Three Mile Island disaster, valve status indications were designed to change colour when a control signal had been sent, rather than reflecting the valve open/closed status. As such, operators had no way of detecting that a valve was stuck in the open position, resulting a partial meltdown of one of the reactors.

Another example is provided in the Kegworth air disaster. Here the design of the engine vibration gauges made it difficult for pilots to see their status. This was a key factor that resulted in pilots shutting down their one functioning engine, eventually resulting in a crash landing in which 47 people died.


By combining the tools and process of UX and UI design, with Human Factor Assurance, SYSTRA provides an integrated service that optimes system safety and performance. We have a complete understanding of agile design thinking and Human Centered Design approaches to software design and experience integrating this within a traditional design and development lifecycles.

SYSTRA Human Factors experts have worked on UX and UI software design and implementation projects for safety critical systems around the world, employing UX and UI design techniques and demonstrate compliance with international and Australian standards.

We use industry leading prototyping / wireframing software to design and evaluate solutions. Furthermore, our extensive knowledge of testing methods enables us to select the most suitable approach to design validation through software and usability testing.

Case Studies
• Electrical Isolation Improvement Program (EIIP), NSW.
ETCS (European Train Control System) L2 (Level 2) Project, QLD.

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