At the helm

  The decision about who should be at the helm depends on the fault and on the situation .

The trigger

• Machine-related: If the trigger is a hardware fault or an inter-unit mismatching, the operators has little to do. It is better that the machine is in charge of keeping the system in the constraints.
• operator-related: If the trigger is a slip, or if the machine cannot identify the trigger, the operator is the one who can do it better, if the conditions enable proper decision making.

The situation

  In case that the trigger is operator-related, the operator needs to decide on the proper corrective action, but the decision might be wrong when operating under stress (for example, AF 447 accident).

  In routine operation and in troubleshooting, the operator may need to decide between alternatives. However, in emergency, in case of confusion, due to the system being in an unexpected state, it may be safer if the machine is in charge of constraining the system behavior.

Example

In the Torrey Canyon accident.

Related topic

Updated on 03 Apr 2016.