Perception-Cognition-Action analysis is included as part of international standard IEC 62366 on the application of usability engineering to medical devices. This approach breaks user interactions down into a sequence of these three components. An error can occur at any point in this chain. When a use error occurs, it may result in hazardous situations. The purpose of PCA analysis is to understand where in this chain errors might occur and then to establish the root cause. This informs what improvements the system requires to avoid potentially hazardous situations. Many of the root causes of hazardous situations identified through PCA analysis strongly pertain to accessibility issues. The Web Content Accessibility Guidelines (WCAG) are an international set of standards developed by W3C to help digital authors create more accessible content for all users, including those with disabilities. These guidelines are built on four principles that provide the foundation for web accessibility (which state that web content must perceivable, operable, understandable and robust). The session will contain case studies in practicing PCA analysis to identify the root causes of potentially hazardous situations, and developing solutions to those problems.