71.55 Control zones

• (a) The Director may designate as a control zone that portion of airspace around an aerodrome if--
  • (1) the Director determines that an aerodrome control service or an aerodrome and approach control service is required; and
  • (2) the traffic density and pattern requires controlled airspace.
• (b) A control zone must be as small as practical consistent with the need to protect the flight paths of IFR flights arriving at and departing from the aerodrome.
• (c) The lateral limits of a control zone must--
  • (1) encompass at least those portions of the airspace that are not within a control area containing the paths of IFR flights arriving at and departing from the aerodrome under IMC; and
  • (2) extend to at least 5 nm from the centre of the aerodrome in the directions from which instrument approaches may be made; and
  • (3) take into account the category of IFR aircraft using the aerodrome and the areas of airspace that need to be protected for those IFR flights.
• (d) Prominent geographical features must be used, where practical, to define the lateral limits of a control zone.
• (e) A control zone with an upper limit above 3000 feet AMSL must coincide with a VFR cruising altitude or flight level prescribed in Part 91.