Visual Meteorological Conditions (VMC)

Definition

Visual Meteorological Conditions (VMC) refer to weather conditions that are clear enough for pilots to fly by visual reference under Visual Flight Rules (VFR). These conditions are defined by minimum visibility, cloud clearance, and ceiling criteria, and are established by ICAO and national aviation authorities. When VMC exist, a flight may be conducted under VFR, and the pilot is expected to maintain visual separation from terrain, obstacles, and other aircraft.

Purpose

  • Define the weather thresholds under which VFR flight is permitted
  • Ensure safe visibility for navigation and collision avoidance
  • Regulate airspace entry and altitude decisions for VFR operations
  • Distinguish between VMC and IMC (Instrument Meteorological Conditions)

VMC Minima (ICAO Standard)

Above 3000 ft AMSL or 1000 ft AGL (whichever is higher)

Airspace Visibility Horizontal Cloud Separation Vertical Cloud Separation
C, D, E, F, G 5 km 1500 m 1000 ft (300 m)

At or below 3000 ft AMSL / 1000 ft AGL

Airspace Visibility Cloud Clearance
G (uncontrolled) 5 km (or 1.5 km for slow aircraft) Clear of cloud and in sight of surface

Note: National authorities (e.g., Austro Control, DFS) may define reduced minima under certain conditions.

CAVOK and VMC

CAVOK (Ceiling And Visibility OK) is a METAR/ATIS abbreviation indicating VMC and the absence of significant weather. If CAVOK is reported, VFR flight is typically permitted.

When VMC Must Exist

  • To initiate and continue a VFR flight
  • To enter or operate within controlled airspace under VFR
  • For Special VFR, with reduced minima in CTRs
  • For visual approach procedures even under IFR clearance

VMC vs. IMC

Condition VMC IMC
Pilot Responsibility Maintain separation visually Rely on ATC separation
Navigation Visual reference Instruments and ATC vectors
Applicable Rules VFR IFR
Cloud Entry Prohibited Permitted with rating/clearance

Phraseology Examples

  • “Maintaining VMC, VFR westbound at 2500 feet.”
  • “Unable to maintain VMC, request IFR clearance.”
  • “VMC reported along the route, expect VFR approach.”

Tips for Pilots

  • ✅ Know your altitude-specific minima before departure
  • ✅ Always monitor visibility and cloud base in flight
  • ✅ Be ready to divert, delay, or request IFR if VMC cannot be maintained
  • ✅ Practice VMC vs. IMC recognition with LearnATC scenario training






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