Prerequisites
- An approved FHA document with classified failure conditions (see Classify Failure Effects and Severity)
- A PSSA document created for the system element (see Create PSSA and SSA Documents)
- Failure conditions assigned a classification and auto-populated DAL (see Assign DAL to Failure Conditions)
How the Allocation Works
The link between a failure condition and a safety requirement uses theallocatesTo link role. This is a bidirectional relationship: the FHA failure condition allocates to the safety requirement, and the PSSA row surfaces the source failure condition through a back-link column called Failure Condition Link.
Steps
1. Open the PSSA document
Navigate to Risks > FCC Preliminary System Safety Assessment (ARP 4761) and open it in Risksheet view. Switch to the Full Analysis view to see all 10 columns.2. Create a new safety requirement row
In the PSSA risksheet, add a new row. The item type issafetyRequirement. Enter the:
- Safety Requirement ID — a unique identifier (e.g.
SR-FCC-001) - Safety Requirement Title — a concise, verifiable objective (e.g. “The FCC shall detect loss of sensor input within 50 ms”)
3. Link the failure condition
In the Failure Condition Link column, click the link picker and search for the source failure condition from the FHA. Select the matchingfailureCondition item.
Once linked:
- The Failure Condition Link column displays the source FHA entry, colored by its ARP 4761 classification
- The DAL Level column auto-populates (A through E) based on inherited classification
4. Assign subsystem ownership
In the Subsystem Allocation column, select the subsystem responsible for implementing this safety requirement (e.g. Sensor Interface Module, Processing Core Module).The subsystem allocation picklist is constrained to system elements defined in your project. Verify the available entries match your system hierarchy in a live Aero1 PSSA module.
5. Record contributing failure modes
In the Contributing Failure Modes column, note any upstreamfailureMode items from DFMEA analyses that contribute to this failure condition. This completes the DFMEA→FHA→PSSA chain.
6. Add a risk control task (optional)
If this safety requirement has an associated mitigation action, link ariskControl item in the Risk Control Tracking column. Risk control items are managed in the Risk Control Plan document.
Classification Inheritance Reference
| FHA Classification | ARP 4761 Level | Inherited DAL | Color |
|---|---|---|---|
| Catastrophic | Cat | A | Red |
| Hazardous | Haz | B | Orange |
| Major | Maj | C | Yellow |
| Minor | Min | D | Green |
| No Safety Effect | NSE | E | Grey |
Verification
You should now see the PSSA row showing the linked failure condition in the Failure Condition Link column with its colored classification badge, and the DAL Level column automatically displaying the corresponding assurance level. The Requirements View will list the safety requirement ID and title with its DAL. Check the Traceability view to confirm theallocatesTo link is active between the FHA failure condition and the PSSA safety requirement.
See Also
- Assign DAL to Failure Conditions
- Classify Failure Effects and Severity
- Create PSSA and SSA Documents
- Review and Approve a Risk Document
Source References (dev)
Source References (dev)
Code:
modules/RiskTemplates/PSSATemplate/attachments/risksheet.json (0.68) · .polarion/tracker/fields/workitem-link-role-enum.xml (0.64) · modules/RiskTemplates/FHATemplate/attachments/risksheet.json (0.64) · datasets/sol-aero-ui-walkthrough/summary.md, navigation.md, dashboards/home-dashboard.md, dashboards/role-dashboards.md, dashboards/standards-compliance.md, risksheet-views/risksheet-views.md, work-item-types/data-model.md (0.60) · modules/RiskTemplates/SSATemplate/attachments/risksheet.json (0.58) · .polarion/tracker/fields/workitem-type-enum.xml (0.58) · .polarion/nextedy/models/rtm.yaml (0.58) · .polarion/nextedy/sheet-configurations/ARP 4761 Safety Assessment Traceability.yaml (0.58) · modules/RiskTemplates/System-FMEATemplate/attachments/risksheet.json (0.57) · .polarion/tracker/fields/failureCondition-classification-enum.xml (0.56)