Near-miss

A near-miss is an unplanned event that had the potential to cause harm, loss, or damage but did not, either by chance or by timely intervention. In safety-critical domains — aviation, medicine, nuclear power, chemical processing — near-misses are among the most valuable sources of information about systemic vulnerabilities, precisely because they reveal failure modes without paying the full cost of actual failure.

The paradox of near-misses is that they are simultaneously the best learning opportunities and the most likely to be ignored. Because no harm occurred, there is often no institutional trigger for investigation. The organization escapes disaster by luck and learns nothing. High-reliability organizations invert this logic: they treat near-misses as evidence that their safety systems are already compromised, and they investigate them with the same rigor as actual accidents. The Swiss cheese model of accident causation depends on this practice: each near-miss is a hole in the cheese, and the accumulation of holes predicts the accident that will eventually occur.