accident

thumb|Green Bank Observatory radio telescope collapsed when a steel plate cracked in 1988. An accident is an unintended and usually undesirable event that is not deliberately caused by humans. Although in ordinary conversations, intentionality is the only factor most people consider, formally, accidents require three factors: it must be unintended, unpreventable, and unexpected. The term accident usually implies the presence of unrecognized or unaddressed risks. Many researchers and professionals in injury prevention discourage the use of the word accident, because the word accident suggests there is no fault, no guilt, no control, and that the situation could not have been anticipated or prevented. Instead, experts emphasize preventable factors that increase risk and worsen outcomes. For example, while a tree falling in a windstorm may not involve human intention, factors such as its condition, placement, or maintenance may contribute to the outcome. Similarly, most road collisions stem from risky behaviour or preventable circumstances rather than being truly accidental; the perception that they are accidents rather than predictable and preventable events was strengthened in the mid-20th century due to automobile industry influence through media.

In recent years worldwide, the most common causes of accidental deaths have been road traffic incidents and falls. Writing of accidental deaths, one author says the "vast majority of accidents are not really accidents of chance, but rather accidents of folly, negligence, and blatant human misjudgment", with research showing that up to 80% of events that are called accidents are caused by human error. Many different theoretical models have been proposed for analyzing accidents, but no single model has yet proved sufficient for these often-complex events.