Air Traffic Control Service
The Air Traffic Control Service domain tests whether you can apply the collision-prevention, separation and clearance rules of ICAO Annex 11 and PANS-ATM (Doc 4444) as implemented in the Kenya Civil Aviation Regulations, inside the Nairobi FIR.
What the service must deliver
ATC service is given to prevent collisions between aircraft, prevent collisions between aircraft and obstructions or vehicles on the manoeuvring area, expedite and maintain an orderly flow of traffic, and give advice and information useful for the safe and efficient conduct of flights (Annex 11, 3.2). In Kenya this is delivered by Nairobi Area Control Centre, approach control units serving Nairobi, Mombasa and Kisumu, and aerodrome control towers.
Separation toolkit
Vertical separation is 1 000 ft in RVSM airspace; 2 000 ft applies above FL290 when an aircraft is not RVSM-approved. Horizontal separation is by time (15 minutes conventionally, reduced with approved RNAV), by lateral track using VOR, NDB or GNSS, or by radar. Aerodrome controllers apply runway separation based on wake category and on whether the preceding aircraft has landed and vacated or is still on the runway. A clearance must be read back whenever it contains a runway, a level, a route or a conditional element.
Worked example
Tower says: '5Y-ABC, behind the landing Boeing 737, line up runway 06.' Reasoning: a conditional clearance is only lawful when the controller can see both aircraft, the condition is unambiguous, and the pilot reads back the condition. If the 737 goes around, the condition fails, the clearance lapses automatically, and the tower must resolve the situation with 5Y-ABC before it enters the runway.
Traps that cost marks
Treating traffic information as a clearance; assuming an aircraft will hold short when only 'line up' was issued; omitting a fresh readback for a level change; mixing altitude on QNH with flight level; applying radar separation minima where no surveillance service is provided.