NIMS Management Characteristics as the Foundation of ICS
The fourteen characteristics
NIMS lists fourteen management characteristics that ICS embodies: common terminology; modular organization; management by objectives; incident action planning; manageable span of control; incident facilities and locations; comprehensive resource management; integrated communications; establishment and transfer of command; unified command; chain of command and unity of command; accountability; dispatch/deployment; and information and intelligence management.
Two that the exam probes hardest
Manageable span of control - a supervisor should oversee 3 to 7 subordinates, with 5 as the working optimum. Span of control drives modular expansion: when a supervisor exceeds about 7, add a level.
Unity of command - each person reports to exactly one supervisor. Chain of command is the ordered line of authority; unity of command is the rule that a person has one boss. Unified Command is different: multiple agencies share command of one incident without a single IC.
Worked example
Two agencies - a fire department and a public works department - respond to a gas main break. Rather than setting up parallel command posts, they form a Unified Command. Together they set one set of objectives on a single ICS 202, and the Planning Section produces one IAP. Public works directs street closures; fire directs evacuation. Each subordinate still reports to one supervisor, so unity of command holds inside Unified Command.
Traps
Span of control is about the number of direct reports, not the number of responders on scene. 'Management by objectives' is a process (understand policy, set objectives, choose strategies, assign tactics, evaluate) - not the same as the IAP itself, which is the written product. Do not confuse unity of command with Unified Command; one is a principle, the other a structure used by multiple agencies.