Editing Incident Command System (section)

===Flexible and modular organization===
Incident Command structure is organized in such a way as to expand and contract as needed by the incident scope, resources and hazards. Command is established in a top-down fashion, with the most important and authoritative positions established first. For example, Incident Command is established by the first arriving unit.

Only positions that are required at the time should be established. In most cases, very few positions within the command structure will need to be activated. For example, a single fire truck at a [[dumpster]] fire will have the officer filling the role of IC, with no other roles required. As more trucks get added to a larger incident, more roles will be delegated to other officers and the Incident Commander (IC) role will probably be handed to a more-senior officer.

Only in the largest and most complex operations would the full ICS organization be staffed.<ref name="autogenerated2007"/> Conversely, as an incident scales down, roles will be merged back up the tree until there is just the IC role remaining.