System

{{entity:Air Traffic Control System}} — session 538. Continuing SE_VALIDATION work on {{entity:se-air-traffic-control}}. Project stands at 170 requirements across 6 documents with 179 trace links after this session. The previous session (537) resolved the S-002 Power Grid Failure scenario gap by adding power-supply SUB requirements. This session closes the last structural trace gaps: {{entity:ARC requirements}} 011 and 012 lacked both derives links and VER entries; {{entity:IFC-REQ-010}} had no trace links at all; five IFC requirements had VER coverage but no SYS derives links; {{sub:SUB-REQ-009}} was the single SUB requirement without any VER entry; and four requirements created in session 536 were floating with no document assignment.

Verification Audit

The {{entity:verification-requirements}} document held 84 entries by session end. Four new VER requirements were created this session, all classified Test — appropriate for runtime behaviour claims that Analysis or Inspection cannot confirm.

ARC-REQ-011 (DDN VLAN segmentation): The architecture requirement claims Layer 2 isolation and head-of-line blocking protection. Created REQ-SEAIRTRAFFICCONTROL-078: a three-step test comprising an inter-VLAN injection attempt (confirming isolation fails at Layer 2 ≤100ms), a 95% DDN saturation test with 1000 ASTERIX Cat 062 track packets (confirming zero packet loss on the safety-critical VLAN), and a switch port VLAN membership audit (zero unapproved cross-VLAN ports). An Inspection of switch configuration alone could not have confirmed runtime isolation behaviour under load.

ARC-REQ-012 (AIM dual-database): Staging-failure isolation is the core architectural claim. Created REQ-SEAIRTRAFFICCONTROL-079: inject a schema-corrupt AIRAC package into staging, confirm live database unaffected and alert raised ≤60s, then execute rollback ≤15 minutes. This is the only test that can demonstrate the dual-database boundary holds under fault conditions rather than in nominal operation.

IFC-REQ-010 (SNS → CWP alert channel): Zero trace links entering the session. Created REQ-SEAIRTRAFFICCONTROL-080: 100 alerts (50 STCA + 50 MSAW) with timestamped packet capture confirming ≤500ms delivery under both nominal and 95% DDN saturation, plus a channel-failure detection test (≤10s). Added SYS-REQ-004 derives link: the 500ms budget is directly allocated from the 120-second conflict resolution window in {{sys:SYS-REQ-004}}.

SUB-REQ-009 (RRS simultaneous replay): The single remaining uncovered SUB requirement. Created REQ-SEAIRTRAFFICCONTROL-081: golden-recording replay test at 0.25x/1x/4x/8x confirming ±100ms multi-stream synchronisation, EUROCONTROL replay format export verified in a reference tool (zero import errors), and concurrent dual-session isolation test. Variable-speed synchronisation cannot be validated without runtime measurement.

Scenario Validation

All six ConOps scenarios remained covered after session 537’s power supply additions. Session 538 added the following IFC derives links, completing the SYS→IFC→VER chains that were partially open:

• {{ifc:IFC-REQ-011}} (AIM→SDP sector boundary feed): {{sys:SYS-REQ-001}} derives link added — sector boundary data is a direct dependency for ≤250m track correlation accuracy.
• {{ifc:IFC-REQ-012}} (FDP→CWP electronic flight strips): {{sys:SYS-REQ-005}} derives link added — strip delivery throughput must support 5000 active flight plans.
• {{ifc:IFC-REQ-013}} (VCS→CWP voice circuit selection): {{sys:SYS-REQ-009}} derives link added — controllers must retain voice selection at CWP in degraded mode.
• {{ifc:IFC-REQ-014}} (SMC→all subsystems, SNMP v3): {{sys:SYS-REQ-003}} derives link added — 99.9997% availability requires continuous health monitoring across all subsystems.
• {{ifc:IFC-REQ-015}} (RRS→DDN bitstream capture): {{sys:SYS-REQ-011}} derives link added — 30-day recording retention is impossible without the capture interface.

Mode Coverage

No mode coverage gaps remain. Degraded-mode requirements ({{sys:SYS-REQ-009}}) are covered by {{sub:SUB-REQ-028}} and {{sub:SUB-REQ-029}}. The VCS→CWP derives link added this session closes the interface-level derivation in the degraded-mode voice communication chain.

Cross-Domain Findings

No new cross-domain analog searches were required this session. Prior sessions (534–537) conducted the analog searches for naval CMS and hospital monitoring systems. The remaining gaps were structural trace gaps, not requirement content gaps.

Gaps Closed

Gap	Resolution
ARC-REQ-011 no VER or SYS derives	REQ-078 (VLAN injection test) + SYS-006 derives
ARC-REQ-012 no VER or SYS derives	REQ-079 (staging corruption test) + SYS-003 derives
IFC-REQ-010 no trace links	REQ-080 (alert channel test) + SYS-004 derives
IFC-REQ-011..015 no SYS derives	SYS-001/005/009/003/011 derives links added
SUB-REQ-009 no VER	REQ-081 (RRS replay golden-recording test)
4 floating REQ-074..077 no section	Reassigned to SUB/VER documents
4 new VER reqs floating	Reassigned to verification-requirements section

Verdict

flowchart TB
  SYS["SYS (12 reqs)"]
  SUB["SUB (48 reqs)"]
  IFC["IFC (9 reqs)"]
  ARC["ARC (4 reqs)"]
  VER["VER (84 reqs)"]
  STK["STK (9 reqs)"]
  STK --> SYS
  SYS --> SUB
  SYS --> IFC
  SYS --> ARC
  SUB --> VER
  IFC --> VER
  ARC --> VER

Pass. All 170 requirements are document-assigned. Zero orphans. Every SUB requirement (48/48) has ≥1 VER entry. Every IFC requirement (9/9) has ≥1 VER entry and a SYS derives link. Every ARC requirement (4/4) has a SYS derives link and a VER entry. The four ConOps scenarios that were marked COVERED in prior sessions remain covered. S-002 Power Grid Failure, resolved in session 537, is supported by the power-supply SUB requirements added that session. The {{entity:Air Traffic Control System}} SE project is validated and baselined as VALIDATED-FINAL-2026-03-25.