Where usability files actually break — and what I do about it

I stopped treating the usability file as a compliance artifact years ago — it’s where product design and real people collide. When it’s done badly, the consequences are more than an audit finding: increased use errors, higher CAPA rates, and slower time‑to‑market. Below are the concrete places I see Human Factors (HF) work fail in Class II products and pragmatic steps I've used to keep the usability file useful, auditable, and tied into risk control. Why the usability file matters (beyond the checkbox) Standards and guidance (IEC 62366‑1, FDA Human Factors Guidance) frame the work, but the goal is safer use. The usability file should: Show you understood who will use the device and how (context of use). Demonstrate that you analysed use‑related hazards and applied risk controls (link to ISO 14971). Provide evidence that controls work (formative + summative testing). If those links are missing, you may have a 40‑page file that still doesn’t prove safety i