During an incident, an incident commander delegates response tasks and objectives based on the situation and their knowledge and experience. In addition to their own skills, the commander may rely on resources from outside the agency or the public to resolve an incident. This is referred to as using operational discretion. The incident commander must ensure that any discretionary action will not jeopardize the safety of their personnel or the public and must be certain that the benefit outweighs the risk.
NIMS is an incident management system that relies on the principle of Management By Objectives (MBO). This approach allows senior responders to delegate responsibility for managing a crisis without excessively burdening themselves or creating unreasonable expectations for subordinate managers. It also takes into account a basic management principle of span of control. The optimal span of control for a supervisor is one supervisor to five subordinates, but this ratio can vary based on the complexity of an incident.
A key part of ICS is the preparation of an Incident Action Plan. This is a written document that outlines the desired outcome, incident objectives and command emphasis/priorities for use during an operational period. This document should be distributed to all supervisory personnel at the Branch, Division/Group and Unit levels.
To ensure that the IAP is effective, the incident commander must actively monitor and evaluate the progress of the response. This includes assessing whether the expected outcomes are being achieved and adjusting the incident objectives if necessary.