"There are many issues that confront the Incident Commander [IC] when responding to an incident that is expanding in complexity. The low frequency of this type of incident can put a great deal of pressure on any IC not only because of the tactical complexity but also the added pressure of managing the communications, resources, planning and support functions needed to react to the growing emergency. The early introduction of the Incident Command System into a complex incident is designed to assist the Initial Response IC in the transition from the reactive mode to the proactive mode of incident management and set up a smooth transfer of command to a superior officer or an incoming Incident Management Team."
Coffee Break Training - Command and Control Series No. CC-2013-3
United States Fire Administration: http://www.usfa.fema.gov/