aviation Aviation includes the activities surrounding mechanical flight and the aircraft industry. ''Aircraft'' includes airplane, fixed-wing and helicopter, rotary-wing types, morphable wings, wing-less lifting bodies, as well as aerostat, lighter- ...

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

visual flight rules In aviation, visual flight rules (VFR) are 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 ...

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

aircraft An 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 by using the Lift (force), dynamic lift of an airfoil, or in ...

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

instrument meteorological conditions In aviation, instrument meteorological conditions (IMC) is a flight category that describes weather conditions that require pilots to fly primarily by reference to instruments, and therefore under instrument flight rules (IFR), rather than by o ...

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

visibility The visibility is the measure of the distance at which an object or light can be clearly discerned. In meteorology it depends on the transparency of the surrounding air and as such, it is unchanging no matter the ambient light level or time o ...

, 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 ...

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 aerospace, which is th ...

, 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 the vertical distance (height, elevation or altitude) of a location in reference to a historic mean sea level taken as a vertical datum. In geodesy, it is formalized as '' orthometric heights''. The ...

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 classes of airspace. Controlled airspace usually imposes higher weather minimums tha ...

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 F ...

(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 regulations promulgated by the executive departments and agencies of the federal government of the United States. ...

, 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