Air Traffic Control / Air Navigation Services: Separation, Clearances and Phraseology
The Air Traffic Control / Air Navigation Services section tests applied separation and procedural control: you are given two or more aircraft, a level or a radar description, and asked for the correct clearance, separation check or readback judgement.
Separation minima to memorise
- Vertical: 1,000 ft up to FL290; 1,000 ft between FL290 and FL410 in RVSM airspace; 2,000 ft above FL410.
- Radar: 5 NM standard; 3 NM only where the State has approved it for a defined TMA or approach control area.
- Longitudinal non-radar: time (commonly 10 minutes on the same track) or DME distance (commonly 10 NM).
- Wake turbulence: Heavy behind Heavy 4 NM, Medium behind Heavy 5 NM, Light behind Heavy 6 NM, Light behind Medium 5 NM.
Clearance and readback discipline
A clearance states identity, limit, route, level and any instructions. The pilot must read back route or limit, runway, altitude or flight level, heading, speed and frequency. Standard words matter: roger means received, wilco means will comply, affirm replaces yes, standby means wait.
Worked example
A Heavy is 4.4 NM ahead of a Medium on final approach, both at 160 kt. The required wake spacing for Medium behind Heavy is 5 NM. Because 4.4 NM is less than 5 NM, the trailing aircraft cannot be cleared to land yet. Slowing it will not open 0.6 NM quickly enough at short final, so the controller vectors it for re-spacing or issues a go-around.
Traps
Applying 3 NM everywhere; quoting 1,000 ft above FL410; treating speed control as a separation standard; using QFE when the clearance is to an altitude referenced to QNH; forgetting that a heading instruction also needs readback.