Controlled Airspace is an airspace of defined dimensions within which air traffic control service is provided in accordance with the airspace classification.
There are 3 services available in controlled airspace:
Flight Information Service
Radar Control Service
Flight Information Service:
A Flight Information Service (FIS) is a non-radar service provided, either separately or in conjunction with other services, for the purposes of supplying information useful for the safe and efficient conduct of flights. Under a FIS the following conditions apply:
Provision of the service includes information about weather, changes of serviceability of facilities, conditions at aerodromes and any other information pertinent to safety.
The controller may attempt to identify the flight for monitoring and co-ordinationpurposes only. Such identification does not imply that a radar service is being provided or that the controller will continuously monitor the flight.
Pilots must be left in no doubt that they are not receiving a radar service.
Controllers are not responsible for separating or sequencing aircraft.
An alerting service is provided to notify appropriate organisations regarding aircraft in need of search and rescue aid, and assist such organisations as required.
Radar Control Service:
a) radar control service may be provided to aircraft operating IFR, SVFR or VFR. When providing the service controllers issue instructions to which:
a) pilots of aircraft operating IFR are required to comply; and
b) pilots of aircraft operating SVFR or VFR will comply unless they advise the controller otherwise.
Semi Cicular rule
Above FL 195 in Class C airspace the semi-circular rule shall apply. Flight levels 200, 220, 240, 260 and 280 shall be westbound; Flight levels 210, 230, 250 and 270 shall be eastbound. Above FL290, cruising levels are allocated according to the RVSM system.
Cruising levels at or above FL 410 up to FL 660 shall be selected according to the
semi-circular rule, therefore, flight levels available are:
Eastbound FL 410, FL 450, FL 490 etc.
Westbound FL 430, FL 470, FL 510 etc.