Degree of control
Control can also be described as how actions are decided upon and
executed, where the degree of detail and function modality, i.e.
degree of possibility to influence the system through a particular
function and at various system levels, plays an important role. On
the basis of this four characteristic degrees of control or modes of
the function in the system can be identified (Hollnagel, 1993):
- Scrambled control. At this level the incident horizon is limi-
ted to the present, meaning that past activity and future poss ible
outcome are not taken into account. The choice of a subsequent
action appears to be random and only one goal at a time is consi-
dered. - Opportunistic control. The incident horizon contains one me-
asure/activity that is chosen to match the present situation and
with only minimal consideration for long term effects. Previous
activities are taken into account to some extent in that the next
one is chosen to match the previous one, but feedback is not al-
ways put to good use. - Tactical control. Here the effects of a measure are taken into ac-
count in the light of what has previously been executed. The next
activity/measure is chosen (to a degree) with care, based on plans
and with consideration for its potential effect. More than one goal
is considered. - Strategic control. At this level the decision maker/commander
is fully aware of the course of events and makes careful plans
for handling the situation, which requires the initiation, coordi-
nation and execution of special activities/measures. The incident
horizon encompasses both the previous activities and future de-
velopments, even if the number of stages that can be planned for
may be limited, even for experts.
Scrambled and strategic control represent two extremes, while
opportunistic and tactical control modes are the most commonly
applied degress of control. The purpose of using these control le-
vels is mainly to be able to describe how the execution of different
activities changes between them, depending on both the outcome
of activities and measures, and the time available.