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5.4 Downwind and Base Leg

5.4.1 General

The downwind and base legs are used to position aircraft for a stable and correctly spaced final approach.

The Approach Controller shall manage these phases to ensure predictable sequencing and separation.

5.4.2 Downwind Leg

The downwind leg is used to establish spacing and prepare aircraft for the base turn.

The Approach Controller shall:

  • Maintain consistent track spacing between aircraft
  • Adjust downwind length to achieve required separation
  • Monitor aircraft speed and relative position
  • Plan the base turn in advance

The downwind leg shall not be extended excessively unless required for spacing.

5.4.3 Spacing on Downwind

The Approach Controller shall:

  • Establish sufficient spacing to allow a stable base turn
  • Prevent compression of traffic
  • Adjust spacing using vectoring and speed control

Spacing shall be managed proactively.

5.4.4 Base Leg

The base turn positions the aircraft for intercept onto final approach.

The Approach Controller shall:

  • Issue the base turn at an appropriate distance from final
  • Ensure adequate spacing exists with preceding traffic
  • Consider aircraft speed and descent profile
  • Plan for a suitable intercept angle

5.4.5 Timing of Base Turn

The Approach Controller shall:

  • Turn aircraft onto base early enough to avoid excessive intercept angles
  • Avoid late turns that result in unstable approaches
  • Ensure the aircraft can intercept final smoothly

Late base turns shall be avoided.

5.4.6 Stability Considerations

The Approach Controller shall ensure that:

  • Aircraft are correctly positioned for final approach
  • Intercept angles are appropriate
  • The aircraft can establish a stable descent

Unstable situations shall be corrected early or a go-around shall be issued.

5.4.7 Limitations

The Approach Controller shall not:

  • Issue late base turns that result in high intercept angles
  • Allow spacing to compress on downwind or base
  • Create unstable approach conditions

5.4.8 Key Principle

Effective downwind and base management ensures a stable final approach.

The Approach Controller shall:

  • Plan ahead
  • Control spacing early
  • Turn base at the correct time

Late base turns result in unstable approaches and increased controller workload.