aviation Aviation includes the activities surrounding mechanical flight and the aircraft industry. ''Aircraft'' include fixed-wing and rotary-wing types, morphable wings, wing-less lifting bodies, as well as lighter-than-air aircraft such as h ...

, visual meteorological conditions (VMC) is an aviation flight category in which

visual flight rules In aviation, visual flight rules (VFR) is a set of regulations under which a pilot operates an aircraft in weather conditions generally clear enough to allow the pilot to see where the aircraft is going. Specifically, the weather must be better tha ...

(VFR) flight is permitted—that is, conditions in which pilots have sufficient visibility to fly the

aircraft An aircraft ( aircraft) is a vehicle that is able to flight, fly by gaining support from the Atmosphere of Earth, air. It counters the force of gravity by using either Buoyancy, static lift or the Lift (force), dynamic lift of an airfoil, or, i ...

maintaining visual separation from terrain and other aircraft. They are the opposite of

instrument meteorological conditions In aviation, instrument meteorological conditions (IMC) are weather conditions that require pilots to fly primarily by reference to flight instruments, and therefore under instrument flight rules (IFR), as opposed to flying by outside visual ref ...

(IMC). The boundary criteria between IMC and VMC are known as the VMC minima and are defined by:

visibility In meteorology, visibility is the measure of the distance at which an object or light can be clearly discerned. It depends on the Transparency and translucency, transparency of the surrounding air and as such, it is unchanging no matter the amb ...

, cloud ceilings (for

takeoff Takeoff is the phase of flight in which an aerospace vehicle leaves the ground and becomes airborne. For aircraft traveling vertically, this is known as liftoff. For aircraft that take off horizontally, this usually involves starting with a tr ...

s and landings), and cloud clearances. The exact requirements vary by type of

airspace Airspace is the portion of the atmosphere controlled by a country above its territory, including its territorial waters or, more generally, any specific three-dimensional portion of the atmosphere. It is not the same as outer space which is t ...

, whether it is day or night (for countries that permit night VFR), and from country to country. Typical visibility requirements vary from one statute mile to five statute miles (many countries define these in metric units as 1,500 m to 8 km). Typical cloud clearance requirements vary from merely remaining clear of clouds to remaining at least one mile away (1,500 m in some countries) 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 Height above mean sea level is a measure of a location's vertical distance (height, elevation or altitude) in reference to a vertical datum based on a historic mean sea level. In geodesy, it is formalized as orthometric height. The zero level v ...

or 1,000 ft AGL (whichever is higher), 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 Controlled airspace is airspace of defined dimensions within which air traffic control (ATC) services are provided. The level of control varies with different airspace class, classes of airspace. Controlled airspace usually imposes higher weat ...

than in uncontrolled airspace. In uncontrolled airspace there is less risk of a VFR aircraft colliding with an

instrument flight rules In aviation, instrument flight rules (IFR) is one of two sets of regulations governing all aspects of civil aviation aircraft operations; the other is visual flight rules (VFR). The U.S. Federal Aviation Administration's (FAA) ''Instrument Fl ...

(IFR) 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 (VFR or IFR), 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: :8 km flight visibility, 1500 m horizontally from cloud, 1000 ft (300m) vertically from cloud Below FL 100: :5 km flight visibility, 1500 m horizontally from cloud, 1000 ft (300m) vertically from cloud At or below 3,000 ft: :5 km flight visibility, clear of cloud and in sight of the surface :or, for an aircraft, other than a helicopter, operating at 140 kt or less: ::1,500 m flight visibility, clear of cloud and in sight of the surface :For helicopters: ::Clear of cloud and in sight of the surface at a speed which is commensurate with the visibility.Manual of Air Traffic Services Part 1
/ref>

Controlled airspace (classes C to E) By Day

At and above FL 100: :8 km flight visibility, 1,500 m horizontally from cloud, 1,000 ft (300m) vertically from cloud Below FL 100: :5 km flight visibility, 1,500 m horizontally from cloud, 1,000 ft (300m) vertically from cloud Alternatively at or below 3,000 and operating at 140kt or less ft: :For helicopters: ::Clear of cloud and in sight of surface with a flight visibility of 1500m

Controlled airspace (classes C to E) By Night

Canada VFR minima

Uncontrolled Airspace (class G):

Surface to 1000 feet 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

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

United States Visual Flight Rules are provided in Title 14 of the

Code of Federal Regulations In the law of the United States, the ''Code of Federal Regulations'' (''CFR'') is the codification of the general and permanent regulatory law, regulations promulgated by the executive departments and agencies of the federal government of the ...

, Part 91, Section 155: ;Notes

References

{{Reflist

External links

U.S. Federal Aviation Regulations defining visual meteorological conditions.Guide to Visual Flight Rules in the UKSERA.5001: Common Rules of the air
Air traffic control Aviation meteorology Visual flight rules