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01.2 Surveillance Systems

1. Overview

Modern ATC surveillance integrates multiple systems to provide accurate aircraft position data.


2. SSR Modes

Mode A

  • 4-digit squawk code

Mode C

  • Pressure altitude

Mode S

  • Unique aircraft identification
  • Enhanced data capability

3. ADS-B

Definition

Automatic Dependent Surveillance – Broadcast

Characteristics

  • GPS-based position
  • High accuracy
  • No interrogation required

4. Multilateration (MLAT)

  • Uses multiple ground stations
  • Calculates aircraft position via time difference

5. System Integration

Controllers must understand:

  • Data reliability differences
  • Update rates
  • Potential discrepancies between sources