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5.7 Sequencing Techniques

5.7.1 General

Sequencing techniques are used to establish and maintain safe and efficient spacing between aircraft.

The Approach Controller shall apply sequencing proactively to ensure stable approaches and continuous traffic flow.

5.7.2 Methods of Sequencing

5.7.2.1 Distance-Based Sequencing

Distance-based sequencing is achieved by maintaining lateral spacing between aircraft.

The Approach Controller shall:

  • Maintain appropriate radar separation (typically 3–5 NM as applicable)
  • Monitor spacing continuously
  • Adjust spacing using vectoring or speed control

Spacing shall not reduce below the prescribed minimum.

5.7.2.2 Time-Based Sequencing

Time-based sequencing is achieved by adjusting aircraft speed to regulate intervals.

The Approach Controller shall:

  • Use speed control to increase or decrease spacing
  • Apply adjustments early to allow aircraft response
  • Ensure spacing remains stable throughout the approach

Time-based sequencing shall support a continuous and predictable flow.

5.7.3 Sequencing Tools

The Approach Controller shall use the following tools:

(a) Radar Vectoring (Primary Tool)

  • Position aircraft within the sequence
  • Adjust track to create or maintain spacing

(b) Speed Control

  • Regulate spacing between aircraft
  • Reduce need for excessive vectoring

(c) Downwind Extension

  • Increase spacing by extending track
  • Used when additional spacing is required

5.7.4 Controller Actions

The Approach Controller shall:

  • Establish the sequence as early as practicable
  • Maintain consistent spacing between aircraft
  • Monitor spacing continuously
  • Adjust sequence proactively

5.7.5 Stability Considerations

The Approach Controller shall ensure that:

  • Sequencing supports stable final approaches
  • Spacing is achieved prior to final intercept
  • Minimal corrections are required on final

5.7.6 Limitations

The Approach Controller shall not:

  • Rely on late corrections to establish spacing
  • Allow spacing to compress on base or final
  • Overload the sequence beyond manageable limits

5.7.7 Key Principle

Effective sequencing is proactive.

The Approach Controller shall:

  • Build the sequence early
  • Maintain spacing continuously
  • Avoid last-minute corrections

Stable sequencing results in safe and efficient operations.