Meteorology

Being instrument rated and flying an IFR flight does not mean to operate aircraft during 0 visibility and 0 vertical visibility/cloud base.

Unless otherwise required by the local regulations and approved by authority, minimum required visibility for take-off is 800m.

For landing, it is always mandatory to meet the minimum visibility latest by passing 1000ft Above Aerodrome Elevation (or Runway threshold). 

The system minimums for ICAO CATI are:

• general visibility 800m
• Runway Visual Range (RVR) touch down zone: 550m
• Runway Visual Range (RVR) midpoint: 125m
• Runway Visual Range (RVR) touch down zone: 75m
• Decision height: 200ft AGL

Above mentioned minimums can be lowered provided the crew, aircraft and airport is authorized for such operation (e.g. CATII or CATII approaches). They may also be increased due to degraded performance or equipment of an aircraft or obstacles in the vicinity.