Swiss Cheese Model — Accident Causation Simulator

Stack several independent defense layers, each riddled with its own random holes, and fire a continuous stream of hazard events straight through them. Most hazards are stopped cold by the first layer that happens to have no hole in their path — a near-miss the system quietly absorbed. Only when the holes of every single layer line up at once does a hazard pass all the way through and register as a breakthrough accident. Adjust layer count, hole density, hole size, how fast the holes drift over time, and the hazard arrival rate, and watch the measured breakthrough rate converge on the theoretical alignment probability computed from the layers' own geometry.