7.4 Arrival Spacing Models
7.4.1 General
Arrival spacing models are structured methods used by the Approach Controller to organise inbound traffic and maintain efficient flow.
The Approach Controller shall select and apply the appropriate model based on traffic demand, runway capacity, and operational conditions.
7.4.2 Basic Model
The basic model is the standard sequencing method used in normal traffic conditions.
The Approach Controller shall:
- Establish aircraft on downwind
- Build spacing on base leg
- Deliver aircraft to final approach in sequence
This model provides structured and predictable sequencing.
7.4.3 Continuous Flow Model
The continuous flow model is used to maximise efficiency and minimise vectoring.
The Approach Controller shall:
- Use speed control as the primary tool
- Minimise heading changes
- Maintain continuous and stable flow onto final
This model is most effective in stable traffic conditions with predictable aircraft performance.
7.4.4 Extended Downwind Model
The extended downwind model is used when traffic demand exceeds normal sequencing capacity.
The Approach Controller shall:
- Extend downwind legs to increase spacing
- Delay aircraft in a controlled manner
- Prevent compression of traffic on base and final
This model allows safe management of high traffic volumes.
7.4.5 Controller Considerations
The Approach Controller shall consider:
- Runway capacity
- Traffic volume and complexity
- Aircraft performance differences
- Weather and operational constraints
Model selection shall support safe separation and manageable workload.
7.4.6 Application
The Approach Controller shall:
- Select the simplest effective model
- Transition between models as traffic conditions change
- Maintain control of the sequence at all times
7.4.7 Limitations
The Approach Controller shall not:
- Allow traffic demand to exceed manageable capacity
- Apply a model unsuitable for current conditions
- Rely on late adjustments to maintain spacing
7.4.8 Key Principle
Arrival spacing models support structured traffic management.
The Approach Controller shall:
- Select the appropriate model
- Maintain spacing proactively
- Ensure stable final approaches
Effective model selection reduces workload and improves efficiency.