Separation Standards and Control Techniques
Separation types
Separation is either vertical, lateral or longitudinal. Vertical separation uses the prescribed minima, commonly 1000 feet below a specified level and 2000 feet above it, depending on the airspace and equipment. Lateral separation uses routes, geographic fixes or NAVAID radials. Longitudinal separation uses time, distance or DME, with minima that depend on the method and the surveillance available.
Control techniques
Know the techniques: vectoring, speed control, level allocation, and the use of reporting points. Speed control must account for aircraft performance and must not be applied below prescribed minima. Radar separation minima depend on the surveillance system and the distance from the antenna. Composite separation combines methods and must be verified.
Traps in questions
Questions often test the vertical separation minimum at high levels or the time-based longitudinal minimum. Another trap is applying radar minima without radar contact, or forgetting that separation responsibility remains with the controller when using speed control. Watch for questions on the effect of wake turbulence categories on separation.
Rule of thumb
State the method, then the minimum, then the condition. Worked example: two aircraft on the same airway at the same level, 15 minutes apart by time, with the leading aircraft faster. The controller must ensure the minimum is maintained; if the gap closes to less than the prescribed time, an alternative method such as level change or speed control is required.