> ## Documentation Index
> Fetch the complete documentation index at: https://learn.nextedy.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Aerospace Safety Model

> A complete requirements traceability matrix for aerospace safety certification, covering DO-178C software assurance, ARP 4754A system development, and ARP 4761 safety assessment.

export const LastReviewed = ({date}) => {
  if (!date) return null;
  const formatted = new Date(`${date}T00:00:00Z`).toLocaleDateString("en-US", {
    year: "numeric",
    month: "long",
    day: "numeric",
    timeZone: "UTC"
  });
  return <p className="mt-10 text-sm text-gray-400 dark:text-zinc-500 not-prose">
      Last reviewed on {formatted}
    </p>;
};

**Industry context:** Aerospace systems must demonstrate bidirectional traceability from customer needs through system decomposition to design implementation and V\&V coverage. Standards such as ARP 4754A Section 5 require this chain to be auditable at every level.

<Frame>
  <img src="https://mintcdn.com/none-17b4493f/-WiVljKlDztH36bB/powersheet/diagrams/reference/example-models/aerospace-safety/diagram-1.svg?fit=max&auto=format&n=-WiVljKlDztH36bB&q=85&s=cfb58c27f809d7612d0dc0427ca41267" alt="diagram" style={{ width: "780px", maxWidth: "100%" }} width="780" height="280" data-path="powersheet/diagrams/reference/example-models/aerospace-safety/diagram-1.svg" />
</Frame>

## Data Model

Seven entity types covering the full aerospace V-model from customer requirements through design characteristics and failure modes. Each entity maps to a Polarion work item type, with safety classification (`sc`/`cc`) propagated at every level.

```yaml theme={null}
domainModelTypes:
  Document:
    properties:
      type:
  Chapter:
    polarionType: heading
  CustomerRequirement:
    polarionType: customerRequirement
    properties:
      outlineNumber:
      description:
      classification:          # sc (Safety-Critical) or cc (Certification-Critical)
  SystemRequirement:
    polarionType: systemRequirement
    properties:
      outlineNumber:
      description:
      classification:
      documentReference:       # Source specification (SRS doc name)
  SubsystemRequirement:
    polarionType: subsystemRequirement
    properties:
      outlineNumber:
      description:
      classification:
      documentReference:
  DesignRequirement:
    polarionType: designRequirement
    properties:
      outlineNumber:
      description:
      classification:
      documentReference:       # Source specification (DRS doc name)
  Characteristic:
    polarionType: characteristic
    properties:
      targetValue:
      tolerance:
      classification:
  FailureMode:
    polarionType: failureMode
    properties:
      severity:
      occurrence:
      detection:

relationships:
  - from: CustomerRequirement
    to: SystemRequirement
    cardinality: one-to-many
  - from: SystemRequirement
    to: SubsystemRequirement
    cardinality: one-to-many
  - from: SubsystemRequirement
    to: DesignRequirement
    cardinality: one-to-many
  - from: DesignRequirement
    to: Characteristic
    cardinality: one-to-many
  - from: Characteristic
    to: FailureMode
    cardinality: one-to-many
```

## Sheet Configuration

Four color-coded column groups provide instant visual orientation across the 4-level hierarchy. Each group uses `collapseTo` so reviewers can collapse an entire requirement level into a single summary column.

```yaml theme={null}
columnGroups:
  customerRequirements:
    groupName: Customer Requirements
    groupStyle: darkgreen
    headerStyle: green
    collapseTo: title
  systemRequirements:
    groupName: System Requirements
    groupStyle: darkpurple
    headerStyle: purple
    collapseTo: systemRequirements.systemRequirement.description
  subsystemRequirements:
    groupName: Subsystem Requirements
    groupStyle: darkteal
    headerStyle: teal
    collapseTo: subsystemRequirements.subsystemRequirement.description
  designRequirements:
    groupName: Design Requirements
    groupStyle: darkblue
    headerStyle: blue
    collapseTo: designRequirements.designRequirement.description

sortBy:
  - columnId: outlineNumber
    direction: asc

columns:
  outlineNumber:
    title: "#"
    width: 80
    formatter: readOnly
    columnGroup: customerRequirements
  title:
    title: Title
    hasFocus: true
    width: 170
    formatter: boldTitle
    columnGroup: customerRequirements
  classification:
    title: SC/CC
    width: 70
    formatter: classificationRenderer
    columnGroup: customerRequirements
  systemRequirements.systemRequirement:
    title: ID
    width: 100
    columnGroup: systemRequirements
  systemRequirements.systemRequirement.description:
    title: Description
    width: 200
    columnGroup: systemRequirements
  systemRequirements.systemRequirement.classification:
    title: SC/CC
    width: 70
    formatter: classificationRenderer
    columnGroup: systemRequirements
  systemRequirements.systemRequirement.testCases.testCase:
    title: System Tests
    multiItem: true
    columnGroup: systemRequirements
    header: &orange
      style: orange
  subsystemRequirements.subsystemRequirement:
    title: ID
    width: 100
    columnGroup: subsystemRequirements
  subsystemRequirements.subsystemRequirement.description:
    title: Description
    width: 200
    columnGroup: subsystemRequirements
  designRequirements.designRequirement:
    title: ID
    width: 100
    columnGroup: designRequirements
  designRequirements.designRequirement.description:
    title: Description
    width: 200
    columnGroup: designRequirements
  designRequirements.designRequirement.testCases.testCase:
    title: Design Tests
    multiItem: true
    columnGroup: designRequirements
    header: *orange
```

## Formatter Examples

<AccordionGroup>
  <Accordion title="SC/CC Classification Renderer">
    Renders safety classification as color-coded pills -- orange for Safety-Critical (SC), red for Certification-Critical (CC).

    ```yaml theme={null}
    formatters:
      classificationRenderer:
      - expression: "context.value == 'sc'"
        style: scStyle
      - expression: "context.value == 'cc'"
        style: ccStyle
    styles:
      scStyle:
        backgroundColor: orange100
        color: orange700
        fontWeight: 600
      ccStyle:
        backgroundColor: red100
        color: red700
        fontWeight: 600
    ```
  </Accordion>

  <Accordion title="4-Tier Severity Formatter">
    Color-codes severity values across the safety assessment hierarchy. Applied to failure mode severity columns in ARP 4761 views.

    ```yaml theme={null}
    formatters:
      severityFormatter:
      - expression: "context.value >= 4"
        style: sevCritical        # red -- immediate safety concern
      - expression: "context.value == 3"
        style: sevMajor           # orange -- significant impact
      - expression: "context.value == 2"
        style: sevMinor           # yellow -- limited impact
      - expression: "context.value <= 1 && context.value > 0"
        style: sevNegligible      # green -- no safety effect
    styles:
      sevCritical:
        backgroundColor: red100
        color: red700
        fontWeight: 700
      sevMajor:
        backgroundColor: orange100
        color: orange800
      sevMinor:
        backgroundColor: yellow100
        color: yellow900
      sevNegligible:
        backgroundColor: green100
        color: green800
    ```
  </Accordion>

  <Accordion title="5-State Compliance Status Formatter">
    Tracks certification objective status per DAL level. Used in DO-178C and DO-254 compliance matrices.

    ```yaml theme={null}
    formatters:
      objectiveStatus:
      - expression: "context.value == 'satisfied'"
        style: statusSatisfied       # green
      - expression: "context.value == 'inProgress'"
        style: statusInProgress      # orange
      - expression: "context.value == 'notStarted'"
        style: statusNotStarted      # red
      - expression: "context.value == 'notApplicable'"
        style: statusNA              # grey
      - expression: "context.value == 'waived'"
        style: statusWaived          # blue
    styles:
      statusSatisfied:
        backgroundColor: green100
        color: green800
      statusInProgress:
        backgroundColor: orange100
        color: orange800
      statusNotStarted:
        backgroundColor: red100
        color: red700
      statusNA:
        backgroundColor: grey200
        color: grey600
      statusWaived:
        backgroundColor: blue100
        color: blue700
    ```
  </Accordion>
</AccordionGroup>

## Named Views

Four views serve different audit and review scenarios:

```yaml theme={null}
views:
  Full RTM:
    # Default view showing all 4 levels with all columns visible

  DAL A Only:
    # Filters to DAL A requirements only -- for the highest assurance level
    columns:
      subsystemRequirements.subsystemRequirement:
        visible: false
      # Hides subsystem level for focused system-to-design view

  Without V&V:
    # Hides test case columns -- requirements-only view for design reviews
    columns:
      systemRequirements.systemRequirement.testCases.testCase:
        visible: false
      designRequirements.designRequirement.testCases.testCase:
        visible: false

  Summary:
    # Executive view -- collapses all groups and hides detail columns
    columns:
      description:
        visible: false
```

## Key Patterns

* **4-level entity nesting** -- the deepest hierarchy demonstrated. Each level has its own color-coded column group for instant orientation during audits.
* **YAML anchors for DRY styling** -- `&orange` / `*orange` reuse header styles across V\&V columns at multiple levels, avoiding repetition.
* **`collapseTo` on every group** -- reviewers collapse entire requirement levels into a single summary column, switching between detailed and overview modes without changing views.
* **`multiItem: true`** for test cases -- many-to-many relationships between requirements and test cases are rendered as expandable lists within cells.
* **SC/CC classification at all levels** -- safety classification propagates from customer through design requirements with consistent visual formatting.
* **`groupBy: chapter`** -- document-structured navigation groups rows by document headings for familiar organization.

## See Also

* [RTM Model](/powersheet/reference/example-models/rtm-model) -- standard 3-level RTM model configuration
* [Columns](/powersheet/reference/sheet-config/columns) -- column configuration options
* [Formatters](/powersheet/reference/sheet-config/formatters) -- formatter and style definitions
* [Sources Configuration](/powersheet/reference/sheet-config/sources) -- expand paths and query configuration

<LastReviewed date="2026-06-08" />