Visual meteorological conditions


In aviation, visual meteorological conditions is an aviation flight category in which visual flight rules 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. The boundary criteria between IMC and VMC are known as the VMC minima and are defined by: visibility, cloud ceilings, and cloud clearances.
The exact requirements vary by type of airspace, whether it is day or night, and from country to country. Typical visibility requirements vary from one statute mile to five statute miles. Typical cloud clearance requirements vary from merely remaining clear of clouds to remaining at least one mile away from clouds horizontally and 1,000 feet away from clouds vertically. For instance, in Australia, VMC minima outside controlled airspace are clear of cloud with 5,000 m visibility below 3,000 ft AMSL or 1,000 ft AGL, and 1,000 ft vertical/1,500 m horizontal separation from cloud above these altitudes or in controlled airspace. Above 10,000 ft, 8,000 m visibility is required to maintain VMC. Air traffic control may also issue a "special VFR" clearance to VFR aircraft, to allow departure from a control zone in less than VMC – this reduces the visibility minimum to 1,600 m.
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 instrument flight rules aircraft emerging from a cloud, so aircraft are permitted to fly closer to clouds. An exception to this rule is class B airspace, in which ATC separates VFR traffic from all other traffic, which is why in class B airspace lower cloud clearance is permitted.

European and UK VFR minima

The following minima apply in Europe and the UK.

Uncontrolled airspace (class F & G)

At and above FL 100:
Below FL 100:
At or below 3,000 ft:

Controlled airspace (classes C to E) By Day

At and above FL 100:
Below FL 100:
Alternatively at or below 3,000 and operating at 140kt or less ft:

Controlled airspace (classes C to E) By Night

At and above FL 100:
Below FL 100:

Canada VFR minima

Uncontrolled Airspace (class G):

Surface to 1000 feet AGL">Height above ground level">AGL

Day: Clear of Cloud. 2 statute miles for fixed wing, 1 statute mile for helicopter

Night: Clear of Cloud. 3 statute miles visibility.

Above 1000 feet AGL">Height above ground level">AGL

Day: 2000 feet horizontally, 500 feet vertically from cloud. 1 statute mile visibility

Night: 2000 feet horizontally, 500 feet vertically from cloud. 3 statute miles visibility

Controlled Airspace (any class B, C, D, E)

1 mile horizontally, 500 feet vertically from cloud. 3 statute miles visibility.

Control Zones (can consist of B thru E)

Maintain at least 500 feet AGL except when taking off or landing.

Class A airspace

VFR flight prohibited in Class A airspace.

US VFR minima

Class G airspace

Surface to 1200 feet AGL:
Day: 1 statute mile visibility, clear of clouds

Night: 3 statute miles, 500 feet below, 1000 feet above, and 2000 feet horizontally from clouds

1200 feet AGL to 10,000 feet MSL:
Day: 1 statute mile visibility, 500 feet below, 1000 feet above, and 2000 feet horizontally from clouds

Night: 3 statute miles, 500 feet below, 1000 feet above, and 2000 feet horizontally from clouds

1200 feet AGL and above 10,000 feet MSL:
Day or Night: 5 statute miles, 1000 feet below, 1000 feet above, and 1 statute mile horizontally from clouds

Class E airspace

At or above 10,000 ft MSL:
Below 10,000 ft MSL

Class C and D airspace

At any altitude:

Class B airspace

Class A airspace