Visual meteorological conditions

     In aviation, visual meteorological conditions (or VMC) is an aviation flight category in which visual flight rules (VFR) flight is permitted—that is, conditions in which pilots have sufficient visibility to fly the aircraft maintaining visual separation from terrain and other aircraft. They are the opposite of Instrument Meteorological Conditions (IMC). The boundary criteria between IMC and VMC are known as the VMC minima. As part of private pilot training, pilots are required to demonstrate some instrument flying skills. This is usually done in the aircraft with simulated IMC conditions using products like blockalls.

    Visual meteorological conditions are usually defined by certain visibility minima, cloud ceilings (for takeoffs and landings), and cloud clearances.

   Generally, VMC requires greater visibility and cloud clearance in controlled airspace than in uncontrolled airspace. In uncontrolled airspace there is less risk of a VFR aircraft colliding with an IFRaircraft emerging from a cloud, so aircraft are permitted to fly closer to clouds. An exception to this rule is class B airspace class, in which ATC separates VFR traffic from other VFR traffic and from IFR traffic, which is why in Class B Airspace lower cloud clearance is required.

Weather Minima for VFR Flight within Controlled Airspace (Classes C to E)

• At and above FL 100

8 km flight visibility, 1500m horizontally from cloud, 1000ft vertically from cloud

• Below FL 100

5 km flight visibility, 1500m horizontally from cloud, 1000ft vertically from cloud

• At or below 3000ft

For fixed wing aircraft operating at 140kt or less 5 km flight visibility Clear of cloud and in sight of surface

For helicopter Clear of cloud and in sight of surface

UK Weather minima for VFR flight outside Controlled Airspace (Classes F and G Airspace)

• At and above FL 100

8 km flight visibility, 1500m horizontally from cloud, 1000ft vertically from cloud

• Below FL 100

5 km flight visibility, 1500m horizontally from cloud, 1000ft vertically from cloud

• At or below 3000ft

for any aircraft: 5 km flight visibility, Clear of cloud and with the surface in sight

or

for an aircraft, other than a helicopter, operating at 140kt or less: 1500 m flight visibility, Clear of cloud and with the surface in sight.

for helicopters: 1500m horizontally from cloud Clear of cloud, with the surface in sight and in a flight visibility of at least 1500m.

Weather Minima for VFR Flight within Controlled Airspace (Classes C to E)

• At and above FL 100

8 km flight visibility, 1500m horizontally from cloud, 1000ft vertically from cloud

• Below FL 100

5 km flight visibility, 1500m horizontally from cloud, 1000ft vertically from cloud

• At or below 3000ft

For fixed wing aircraft operating at 140kt or less 5 km flight visibility Clear of cloud and in sight of surface

For helicopter Clear of cloud and in sight of surface

 Weather minima for VFR flight outside Controlled Airspace (within Class E Airspace)

• At or above 10,000 ft. MSL

5 statute miles visibility, 1 statute mile horizontally from clouds, 1000ft above and below clouds

• Below 10,000 ft. MSL

3 statute miles visibility, 2000 ft. horizontally from clouds, 1000ft above and 500 ft below clouds

US Weather minima for VFR flight in Class C and D airspace

3 statute miles visibility, 2000 ft. horizontally from clouds, 1000ft above and 500 ft below clouds