System

Air Traffic Control System ({{entity:Air Traffic Control System}}, {{hex:51F57BD9}}), session 504. The project entered this session with 91 requirements across 6 documents, 56 trace links, and only 7% verifies coverage — 12 VER entries for 46 SUB and 9 IFC requirements. The entity namespace SE:air-traffic-control contained leaked entities from the previous session’s RC airplane work, which were cleared by deduplication before engineering commenced.

Decomposition

No new subsystem decomposition was required this session — the 11 primary subsystems were already classified and stored from prior sessions: {{entity:Surveillance Data Processing}}, {{entity:Safety Net System}} ({{hex:51F77B59}}), {{entity:Flight Data Processing}}, {{entity:Controller Working Position}}, {{entity:Voice Communication System}}, {{entity:Recording and Replay System}}, {{entity:Data Distribution Network}}, {{entity:System Monitoring and Control}}, {{entity:Aeronautical Information Management}}, {{entity:Controller Pilot Data Link Communications}}, and {{entity:Approach Sequencing and Metering}}.

The primary work was verification gap-filling: 10 new VER requirements were added via bulk create targeting the subsystems with zero or partial coverage, plus 20 trace links establishing the STK→SYS→SUB→VER chain. VER coverage rose from 7% (6/91) to 22% (22/102).

flowchart TB
  ATCS[Air Traffic Control System]
  SDP[Surveillance Data Processing]
  SNS[Safety Net System]
  FDP[Flight Data Processing]
  CWP[Controller Working Position]
  VCS[Voice Communication System]
  RRS[Recording and Replay System]
  DDN[Data Distribution Network]
  SMC[System Monitoring and Control]
  AIM[Aeronautical Information Management]
  CPDLC[Controller Pilot Data Link Comms]
  AMAN[Approach Sequencing and Metering]
  ATCS --> SDP
  ATCS --> SNS
  ATCS --> FDP
  ATCS --> CWP
  ATCS --> VCS
  ATCS --> RRS
  ATCS --> DDN
  ATCS --> SMC
  ATCS --> AIM
  ATCS --> CPDLC
  ATCS --> AMAN

Analysis

The {{entity:Safety Net System}} ({{hex:51F77B59}}) carries the highest safety integrity level in the system. Its {{trait:Functionally Autonomous}} trait correctly captures autonomous conflict detection behaviour independent of controller input. The SNS shares 91% Jaccard similarity with the top-level {{entity:Air Traffic Control System}} itself — reflecting that SNS requirements account for nearly all safety-critical constraints at the system level. This is consistent with EUROCONTROL ESARR 4’s identification of STCA as the primary safety barrier for en-route separation.

Lint analysis produced 25 high-severity findings, all categorised as “Powered but no power requirements”. These are {{trait:Powered}} trait false positives: the subsystems are correctly classified as Powered (they run on server infrastructure with electrical input), but ATC software subsystem requirements conventionally address power resilience at the system level ({{sys:SYS-REQ-007}} dual power supply, {{sys:SYS-REQ-009}} degraded mode) rather than per-subsystem power budget specifications. This lint finding class is acceptably deferred for ground-based ATC systems.

Requirements

New VER entries added cover: SNS conflict prediction look-ahead test ({{sub:SUB-REQ-003}}), Minimum Safe Altitude Warning replay verification ({{sub:SUB-REQ-013}}), SDP multi-sensor simultaneous ingestion ({{sub:SUB-REQ-001}}), SDP track identity re-acquisition ({{sub:SUB-REQ-010}}), FDP flight plan lifecycle including surveillance gap persistence ({{sub:SUB-REQ-005}}), CPDLC delivery latency confirmation at 99th percentile ({{sub:SUB-REQ-025}}), AIM NOTAM propagation within 60s with cryptographic validation, DDN switch failure survivability under traffic load ({{sub:SUB-REQ-005}}), SMC health anomaly detection within 10s for each subsystem, VCS channel independence to -60 dBc, and RRS concurrent replay without live recording degradation.

Trace links created: 8 STK→SYS derives covering the full stakeholder-to-system derivation chain, 5 SYS→SUB derives on the safety-critical path (SYS-004→SNS, SYS-001→SDP, SYS-003→DDN, SYS-009→SDP failover, SYS-011→RRS), and 11 VER→SUB verifies links. Final state: 102 requirements, 87 trace links, 4 diagrams.

Next

Add VER entries for remaining uncovered SUB requirements: Controller Working Position (3 reqs), Aeronautical Information Management (4 reqs), AMAN (2 reqs), VCS (1 req), CPDLC (4 reqs). Add IFC→VER trace links for all 9 IFC requirements. Create derives links for 4 ARC requirements to SYS/SUB targets. Dismiss Powered lint class as documented false positive and create lint baseline.