The Loss Hazard Safety Constraint Table is a pivotal component in STPA (System-Theoretic Process Analysis) for defining specific losses that your system aims to prevent. This table facilitates the identification of hazards—specific system states or conditions posing a risk of loss. It also serves to establish safety constraints, which are measures or conditions required to mitigate identified hazards. This step is critical for delineating the system’s safety requirements and strategies for risk reduction.
Navigate to [Diagram] → [STAMP/STPA] → [Loss Hazard Safety Constraint Table].
Alternatively:
1. Go to [File] → [New].
2. Select the [STPA Procedure] tab, double-click on [Identify Loss, Hazard, Safety Constraint].
To insert a loss, right-click on the table and select [Add Loss].
Once a loss is listed, associate hazards that could lead to this loss. Right-click on the [Loss] field and select [Add Loss].
To link a hazard to multiple losses, use the [Add Existing Hazard] dropdown list to attach an existing hazard.
For defining safety constraints associated with a loss and its hazard, right-click on the [Safety Constraint] field and choose [Add Safety Constraint].
If a safety constraint applies to several hazards, select it from the [Add Existing Safety Constraint] dropdown list.
By default, Astah assigns IDs (e.g., L1, L2 for Losses; H1, H2 for Hazards) automatically.
To edit these IDs, double-click on them.
To disable automatic ID assignment: