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10. Safety & Monitoring

10.1 Use of Safety Nets (STCA, MSAW)

The TopSky ATM system provides automated safety net alerts such as:

  • Short-Term Conflict Alert (STCA): Generates early warning of potential loss of separation between aircraft. STCA is intended to support, not replace, controller vigilance.
  • Minimum Safe Altitude Warning (MSAW): Alerts controllers when an aircraft is in proximity to terrain or obstacles below the minimum safe altitude.

Controllers shall treat these alerts as high-priority events, verify their accuracy, and take immediate action as necessary to resolve any unsafe condition. Alerts must not be disregarded without a valid operational reason.

10.2 Conflict Detection & Resolution

Controllers shall continuously scan for potential conflicts using both automation tools and manual observation. When a potential conflict is detected:

  • Early intervention is essential—apply lateral, longitudinal, or vertical separation as appropriate.
  • Prioritization should be given to resolving conflicts closest in time and distance.
  • Coordination with affected sectors or FIRs should be initiated immediately if traffic is approaching boundaries.

Preventive action is preferable to reactive measures. Controllers should not rely solely on STCA to identify developing conflicts.

10.3 Minimum Radar Vectoring Altitude (MRVA)

Radar vectoring must only be provided above published Minimum Radar Vectoring Altitudes (MRVAs), which ensure terrain clearance in areas of radar coverage. If MRVA charts are not available, vectoring must be applied conservatively above the Minimum Sector Altitude (MSA).

Controllers must maintain situational awareness of MRVA limits and avoid vectoring aircraft into areas of rising terrain, particularly during descent and in non-radar environments.

10.4 Terrain & Obstacle Avoidance

Ensuring adequate clearance from terrain and obstacles is a fundamental safety responsibility in enroute airspace.

The sector files are equipped with the TopSky ATM system, which includes integrated Minimum Radar Vectoring Altitudes (MRVA) and Grid Minimum Off-Route Altitudes (Grid MORAs). These provide visual and automated reference for minimum safe altitudes across the FIR.

  • Radar vectoring shall only be conducted at or above the displayed MRVA for the relevant area.
  • In procedural or non-radar environments, aircraft must be cleared at or above the applicable Grid MORA or published minimum enroute altitudes to ensure terrain clearance.
  • Controllers must be particularly vigilant when vectoring near mountainous regions or in areas of degraded surveillance, such as FIR boundaries or oceanic sectors.

The built-in TopSky altitude references enhance situational awareness and terrain avoidance, but controller judgment remains essential when managing altitude assignments in dynamic or high-workload scenarios.

10.5 Unauthorized Entry Handling

When an unauthorized or unknown aircraft enters the FIR, controllers will receive an AIW (Airspace Infringement Warning) alert via the TopSky ATM system.

Upon receiving an AIW warning, controllers shall attempt to establish communication with the aircraft on all available frequencies. If contact cannot be made, a general safety broadcast should be issued on guard or common VHF frequencies to alert the aircraft.

Controllers must ensure other traffic maintains safe separation from the unidentified aircraft and coordinate with adjacent FIRs as necessary, providing details such as position, heading, and altitude.

In the VATSIM environment, unauthorized entries are uncommon but may occur due to flight plan errors or simulation discrepancies. Prompt recognition and response to AIW alerts are essential for maintaining airspace safety.

10.6 Continous Monitoring & Interventions

Controllers shall continuously monitor all aircraft within their sector, ensuring:

  • Compliance with assigned clearances, altitudes, and routes.
  • Prompt detection of deviations from expected flight paths or performance.
  • Timely intervention when any separation risk, safety concern, or pilot non-compliance is observed.

Interventions should be firm, clear, and followed up with corrective instructions. Monitoring includes both airborne and coordination aspects (e.g., ensuring handoffs are completed, aircraft contact is established, and safety nets are functioning as expected).

Safety is maintained not only by adherence to separation standards but also through active vigilance and professional judgment at all times.