What term identifies the event that determines the nature and specifics of an accident?

The term that identifies the event determining the nature and specifics of an accident is "Key Event." This term is used to refer to the critical moment within the sequence of actions leading up to an accident that establishes the primary cause or circumstances surrounding it. By identifying this key event, investigators can better analyze the factors that contributed to the accident, understand the sequence of actions that led to it, and determine the necessary steps to prevent similar occurrences in the future.

While other terms may refer to various aspects of accidents, they do not encapsulate the pivotal role that the key event plays in accident analysis. For instance, "Crasher Event," "Impact Event," and "Collision Event" all focus on specific aspects of the accident's physical manifestations but do not address the broader context that the key event signifies in understanding the overall sequence and causation of the incident.