4.7 VMC vs IMC

4.7.1 APP in coordination with TWR shall declare a CTR “IMC” when the ceiling drops below 1500ft and/or the visibility drops below 5000m in any portion of the CTR even though VMC may prevail at one or more of the aerodromes in the CTR.

4.7.2 TWR is required to inform APP when IMC prevails at their aerodrome and APP shall be responsible for declaring the CTR “IMC” and for taking the following action:

  1. inform all TWR controllers in the CTR and arrange liaison in accordance with Division ATC Procedures;
  2. inform, or request ACC to inform all aircraft bound for that CTR, that it is “IMC”. This is especially important in respect of aircraft on VFR flight plans as they will either have to divert or obtain IFR or SVFR clearances.

4.7.3 TWR are required to inform APP when the weather conditions at their aerodrome have improved to the stage that compliance with IFR is no longer a requirement.

4.7.4 When APP is satisfied that VFR operations are possible throughout the CTR it shall declare the CTR “VMC” and inform all TWR controllers in the CTR.

4.7.5 The state of a CTR should not be improved from IMC to VMC unless there is likely to be a lasting improvement in weather conditions.