Logistics provides support to meet incident needs, provides resources and all other services needed to support the incident. The adaptability of ICS stems from the ability to expand or contract the organization as necessary. Small incidents may be managed by one person, the Incident Commander. Large incidents require the functions of ICS to be set up as separate sections, which may be further subdivided. A basic principle that allows the ICS to expand and contract smoothly during an incident is that the person at the top is responsible until the authority is delegated to another person.
Span of control is maintained at three to seven employees per supervisor.
In some incidents, including oil spills, there are several organizations that may have shared authority to respond. ICS has the advantage of combining different Federal, State, and Local agencies and the Responsible Party into the same organizational system maximizing coordination of spill response activities and avoiding duplication of efforts. A structure called Unified Command allows the Incident Commander position to be shared among several agencies and organizations that have jurisdiction. This group sets the overall incident objectives and guides and approves the incident action plan. The Unified Command members retain their authority, but work to resolve issues in a cooperative fashion so maximum attention is given to response efforts.