Aerospace Safety Model - Nextedy Documentation

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.

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.

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.

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

SC/CC Classification Renderer

Renders safety classification as color-coded pills — orange for Safety-Critical (SC), red for Certification-Critical (CC).

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

4-Tier Severity Formatter

Color-codes severity values across the safety assessment hierarchy. Applied to failure mode severity columns in ARP 4761 views.

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

5-State Compliance Status Formatter

Tracks certification objective status per DAL level. Used in DO-178C and DO-254 compliance matrices.

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

Named Views

Four views serve different audit and review scenarios:

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.

​Data Model

​Sheet Configuration

​Formatter Examples

​Named Views

​Key Patterns

​See Also

Data Model

Sheet Configuration

Formatter Examples

Named Views

Key Patterns

See Also