[STPA] Accident Hazard Safety Constraint Table
Accident Hazard Safety Constraint Table is where you define the Accidents and Losses that you want the system to prevent, and identify hazards – system state or set of conditions that will lead to a loss and the safety constraints.
Create an Accident Hazard Safety Constraint Table
Go to [Diagram] – [STAMP/STPA] – [Accident Hazard Safety Constraint Table].
Or
1. Go to [File] – [New]
2. Select [STPA Procedure] tab and double-click [Identify Accident, Hazard, Safety Constraint]
Add Accidents
To add an accident, right-click on a the table and click [Add Accident].
Add Hazards
After an Accident is created, you can enter the hazard that could lead to the accident by right-clicking on the [Hazard] field and click [Add Hazard].
Each hazard could lead to one or more accidents. In that case, you can choose an already existing Hazard from the drop-down list from [Add Existing Hazard] menu to another accident to multiple accidents.
Add Safety Constraints
When an accident and its hazard are defined, you can add the safety constraint.
Right-clicking on the [Safety Constraint] field and click [Add Safety Constraint].
A single safety constraint could be related to one or more hazards. In that case, you can choose an already existing safety constraint to multiple Hazards from [Add Existing Safety Constraint] and choose one from the drop-down list.
Disable automatic ID creation
When you add Accidents, Hazards and Safety Constraints, Astah automatically gives ID starting from A1, A2, A3…for Accidents and H1, H2, H3…for Hazards…etc.
You can directly edit it by double-clicking the ID. If you do not wish to have Astah to allocate the ID,
- Go to [Tools] – [System Properties]
- A [System Properties] window appears. Select [Other] under [STAMP/STPA]
- Remove the tick off [Automatically Assign IDs] option and click [Apply] – [OK].
Please be noted that this change will stop automatically creating ID for all the other definitions such as Preconditions and Countermeasures.