Operational ambiguity

The problem

Operators are expected to follow operational rules, even when they are implicit.

Operational ambiguity

Common sources of operational failure are:

• Design ambiguity: designers may interpret the specified requirements in different ways
• Operation ambiguity: the operators do not know, understand and obey operational rules that they are supposed to follow.

Sources

Operational ambiguity is due to designing and operation while assuming implicit operational rules, which might be interpreted in various ways..

Examples

• The design of the TMI nuclear power plant enabled the operators to close the backup cooling system ( Perrow ).
• The design of the navigation handle of the Torrey Canyon supertanker enabled the operators to change it to the Control position, which disconnected the wheel from the rudder (Casey ).

  If the rules are implicit, then the operators might execute maintenance activities in functional operation. Sometimes, these activities are risky, especially, when the maintenance activities involve safety add-ons.

Related topic

Updated on 26 Mar 2017.