Checklist
COMPLETE
Degraded Mode of Operation is a condition where normal ATM services are reduced due to equipment outage/malfunction, loss of supporting systems, communications limitations, or staffing constraints, requiring procedural mitigations to maintain safety.
SDD shows no radar picture OR all tracks lost │ ├─► Check other positions’ SDD? YES → Local display issue → see “SDD Display Issues” │ ├─► NO → No surveillance everywhere │ ├─► General broadcast (ACC/APP): “Non-radar — vectors suspended” │ ├─► Establish procedural separation │ • Temporary 500 ft vertical if required + traffic information │ • Coordinate releases with adjacent sectors/units │ ├─► Assign procedural executive (Surveillance controller assists) │ ├─► TWR/SMC: Suspend circuits; add “non-radar delays” to ATIS │ └─► Continue on procedural until stable restoration → revert with caution
“No display” OR “Labels frozen” OR “Laggy cursor”
│
├─► Move to alternate SDD (sector fallback list)
│
├─► Alternate OK → Continue ops; WSO re-sectorises if needed
│
├─► Frozen everywhere → Suspect SDP → Use BYPASS Mode
│
└─► Tower-only issue:
• APP provides positions (20 NM etc.)
• If no ASMGCS: RWY02 (4 ILS-DME / 7 VOR-DME) or RWY20 (3 VOR-DME)
“Frozen SDD” or “No hand-offs/MTCD” after SDP/LAN issue │ ├─► On SDD: Operational Mode → BYP │ ├─► Radar Source (LDISGT) → select one sensor │ ├─► Announce limitations: no correlation / no safety nets / no hand-off │ └─► Control within reliable coverage; revert after restoration (cross-check)
Coverage holes OR only ADS-B tracks visible
│
├─► Confirm healthy sensors / reliable coverage
│
├─► Within coverage → surveillance control
│
├─► Beyond coverage → procedural separation
│
└─► ADS-B only:
• Verify equipage
• Tighten coordination departures/arrivals
FPL functions/estimates missing on FDD │ ├─► Create minimal FPLs manually (imminent arrivals first) │ ├─► Manual tagging; use RBL for exit estimates │ └─► Paper strips; phone coordination with adjacent sectors/units
Frozen display at all SDDs │ ├─► Select BYPASS mode │ ├─► Choose single radar source │ └─► Announce limitations; continue with raw returns
No radar feed from RDCU / loss after switchover │ ├─► Area/APP broadcast → stop vectoring │ ├─► Establish procedural separation (temp 500 ft if needed) │ └─► TWR: suspend circuits; update ATIS
Main LAN down OR all LANs down │ ├─► Main LAN → BYPASS (single sensor) │ └─► All LANs → Treat as complete surveillance failure → procedural
No incoming AIDC/FPL delivery │ ├─► Create inbound FPLs manually (MCD) │ └─► Phone coordination with adjacent units; log
“No transmit” or “No receive” on sector frequency
│
├─► Try standby/guard/alternate set
│
├─► Use man-pack/J-controller; combine positions if needed
│
└─► Total ground radio failure:
• 121.5 monitoring; inform adjacent units
• Hold/reroute as per MATS
ATS lines/Internal phones down │ ├─► Use written notes with signatures for releases/estimates │ ├─► Apply LOA fallbacks (alternate lines; mobile last) │ └─► Inform CNS/ATS-I/C; log
ATIS/monitoring indicates ILS U/S │ ├─► Broadcast change; offer LOC-only / VOR approach │ ├─► Vector accordingly; brief any MAP change │ └─► Check minima; update ATIS
“GGT VOR U/S” │ ├─► Broadcast (exclude non-GGT routes if applicable) │ ├─► Do not apply separations that depend on VOR fixes │ └─► Use ILS/LOC/NDB/other aids; ATIS/NOTAM; log
Roll-down flags FDPS/MLAT/APP/SMR OR targets missing │ ├─► Do NOT use A-SMGCS for Aerodrome Control │ └─► Use visual procedures/lights/phraseology; report to Control Room & WSO
Local RVR panel U/S OR inconsistent readings │ ├─► Do NOT use local panel values │ └─► Obtain manual RVR from MET; enforce LVP/LVTO minima; log
Building evacuation OR facility unfit │ ├─► Declare relocation to Backup ATC (Watch Tower Fire Station) │ ├─► Move minimal team + essential comms/paperwork │ └─► Establish frequencies/coordination; broadcast status; log capacities