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How DAL Assignment Works

DAL assignment in the Aerospace Safety Solution is automatic — once you set the ARP 4761 classification on a failure condition, the dalAllocation field is computed by formula and cannot be overridden manually. This enforces the traceability chain from ARP 4761 safety assessment to DO-178C (software) and DO-254 (hardware) certification objectives. diagram

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Classification-to-DAL Mapping

ClassificationProbability TargetDALColour
CatastrophicExtremely Improbable (< 10⁻⁹)DAL ARed
HazardousExtremely Remote (< 10⁻⁷)DAL BOrange
MajorRemote (< 10⁻⁵)DAL CYellow
MinorReasonably ProbableDAL DGreen
No Safety Effect—DAL EGrey

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Steps

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1. Open the FHA risksheet

Navigate to 3 - Risks and open the document named FCC System Functional Hazard Assessment (ARP 4761) (or the equivalent FHA for your project).

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2. Locate the failure condition row

Find the row for the failure condition you want to assign. The risksheet is sorted by Function → Failure Condition → Flight Phase.

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3. Set or confirm the Classification field

In the Classification column group, click the Classification cell and select the appropriate ARP 4761 severity level:
  • Catastrophic — prevents continued safe flight and landing
  • Hazardous — large reduction in safety margins
  • Major — significant reduction in safety margins
  • Minor — slight reduction in safety margins
  • No Effect — no impact on safety
The cell renders with colour coding matching the severity.

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4. Observe the auto-populated DAL

As soon as classification is saved, the DAL column in the DAL Allocation group updates automatically. The value is read-only — it reflects dalAllocation derived from the classification field.
Failure conditions classified as No Safety Effect produce DAL E. You can assign them quickly without creating safety requirements — they do not generate DO-178C or DO-254 compliance objectives.

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5. Verify the linked Safety Requirement

The Safety Requirements column group shows the safety requirement (safetyRequirement work item) linked via allocatesTo. Confirm that:
  • SR ID is populated — a safety requirement has been created for this failure condition
  • DAL Level in the Safety Requirements group matches the DAL Allocation column
If no SR ID appears, use the + Safety Requirement toolbar action to create and link one.
If you change a failure condition’s classification after the linked safety requirement has already been reviewed or approved, the dalAllocation field updates immediately — but the safety requirement’s dalLevel field may not update automatically. Open the linked safety requirement and confirm the dalLevel field matches the new DAL before proceeding to PSSA.

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6. Set the Probability Target

In the Classification column group, confirm the Probability Target cell reflects the correct value for the assigned classification (see table above). This field is separate from dalAllocation and must be recorded explicitly as part of the FHA evidence.

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7. Update Verification Status

In the Verification column group, update the Verification Status field to In Progress once the DAL is assigned and the safety requirement is created. Set it to Completed when analysis evidence is gathered.
Reclassifying a failure condition from, for example, Major (DAL C) to Hazardous (DAL B) triggers additional PSSA objectives. Any PSSA safety requirements already scoped for DAL C will need to be reviewed for DAL B compliance. Coordinate with the safety team before reclassifying approved failure conditions.

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Verification

You should now see:
  • The DAL column shows a colour-coded value (A–E) matching the classification
  • The SR ID column shows a linked safety requirement with the correct DAL Level
  • The Verification Status is set appropriately for the current analysis phase

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See also

Code: modules/RiskTemplates/FHATemplate/attachments/risksheet.json (0.64) · .polarion/nextedy/models/rtm.yaml (0.61) · .polarion/tracker/fields/safetyRequirement-custom-fields.xml (0.55) · 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 (0.54) · .polarion/tracker/fields/dal-enum.xml (0.54) · .polarion/tracker/fields/failureCondition-classification-enum.xml (0.52) · .polarion/tracker/fields/complianceObjective-standard-enum.xml, complianceObjective-status-enum.xml, complianceRequirement-complianceStatus-enum.xml, complianceRequirement-evidenceType-enum.xml (0.51) · modules/RiskTemplates/PSSATemplate/attachments/risksheet.json (0.50) · .polarion/tracker/fields/failureCondition-custom-fields.xml (0.49) · .polarion/nextedy/sheet-configurations/DO-160G Environmental Qualification.yaml, Component RTM.yaml, Configuration Index.yaml, Design Verification Sheet.yaml, Interface Control Matrix.yaml, Problem Report Tracker.yaml, Process Steps.yaml, Review Action Item Tracker.yaml, SOI Stage Gate Dashboard.yaml, Use Steps Specification.yaml, User Need Validation Sheet.yaml, characteristics.yaml, component-characteristics.yaml, customer-requirements.yaml, design-requirements.yaml, subsystem-functions.yaml, subsystem-verification.yaml, system-elements.yaml, test-verification.yaml (0.48)