Which Incident Type is described by multiple operational periods and requires a written IAP?

The correct choice identifies an Incident Type characterized by multiple operational periods and the necessity for a written Incident Action Plan (IAP). In the context of the Incident Command System, Type 3 incidents typically involve a complex situation that requires a greater degree of coordination and resources than smaller incidents. These incidents often necessitate detailed planning to effectively manage the operations, logistics, and resources over several operational periods.

The requirement for a written IAP is crucial in Type 3 incidents as it enables clear communication among responders, delineates objectives, strategies, and assignments, and ensures that all personnel involved in the incident are operating from a shared understanding of the incident response. This level of formal documentation is essential for tracking progress, assessing effectiveness, and providing a framework for accountability throughout the duration of the incident.

In contrast, other Incident Types either may not require multiple operational periods or do not necessitate a comprehensive written IAP, as their scale and complexity can be adequately managed through less formal methods.