Visual meteorological conditions
In aviation, visual meteorological conditions (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 and are defined by: visibility, cloud ceilings (for takeoffs and landings), and cloud clearances.
The exact requirements vary by type of airspace, 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 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 than in uncontrolled airspace. In uncontrolled airspace there is less risk of a VFR aircraft colliding with an instrument flight rules (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
[edit]The following minima apply in Europe[1] and the UK.
Uncontrolled airspace (class F & G)
[edit]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.[2]
Controlled airspace (classes C to E) By Day
[edit]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
[edit]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[2]
Canada VFR minima
[edit]Day: Clear of Cloud. 2 statute miles for fixed wing, 1 statute mile for helicopter
Night: Clear of Cloud. 3 statute miles visibility.
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)
[edit]1 mile horizontally, 500 feet vertically from cloud. 3 statute miles visibility.[4]
Control Zones (can consist of B thru E)
[edit]Maintain at least 500 feet AGL except when taking off or landing.[5]
Class A airspace
[edit]VFR flight prohibited in Class A airspace.
US VFR minima
[edit]United States Visual Flight Rules are provided in Title 14 of the Code of Federal Regulations, Part 91, Section 155:[6]
| Airspace class | Time | Altitude | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Surface to 1200 feet AGL[b] | 1200 feet AGL to 10,000 feet MSL | 1200 feet AGL and above 10,000 feet MSL | |||||||
| Visibility[c] | Clearance from clouds[d] | Visibility[c] | Clearance from clouds[d] | Visibility[c] | Clearance from clouds[d] | ||||
| G | Day | 1[e] | clear of clouds[f] | 1 | 500 below, 1000 above, 2000 horizontally | 5 | 1000 below, 1000 above, 1 SM horizontally | ||
| Night | 3[g] | 500 below, 1000 above, 2000 horizontally[f] | 3 | 500 below, 1000 above, 2000 horizontally | |||||
| Airspace class | Time | Altitude | |||||||
| Below 10,000 feet MSL | At or above 10,000 feet MSL | ||||||||
| Visibility[c] | Clearance from clouds[d] | Visibility[c] | Clearance from clouds[d] | ||||||
| E | Day or night | 3 | 500 below, 1000 above, 2000 horizontally | 5 | 1000 below, 1000 above, 1 SM horizontally | ||||
| Airspace class | Time | Any altitude | |||||||
| Visibility[c] | Clearance from clouds[d] | ||||||||
| D | Day or night | 3 | 500 below, 1000 above, 2000 horizontally | ||||||
| C | |||||||||
| B | Clear of clouds | ||||||||
| A | Prohibited[h] | ||||||||
- Notes
- ^ Rules for helicopters/rotorcraft noted as exceptions.
- ^ Except as provided for in §91.155, paragraph (b).[6]
- ^ a b c d e f In statute miles (SM)
- ^ a b c d e f In feet, unless otherwise noted
- ^ For helicopters: 1⁄2 SM
- ^ a b For helicopters: clear of clouds
- ^ For helicopters: 1 SM
- ^ Exception for emergency NORDO operations. Pilots in Class A airspace must be instrument rated, operating with an IFR flight plan, and aircraft must be equipped with 2-way radios, a Mode-C Transponder, and ADS-B out.
See also
[edit]References
[edit]- ^ Commission Implementing Regulation (EU) No 923/2012 of 26 September 2012 laying down the common rules of the air and operational provisions regarding services and procedures in air navigation and amending Implementing Regulation (EU) No 1035/2011 and Regulations (EC) No 1265/2007, (EC) No 1794/2006, (EC) No 730/2006, (EC) No 1033/2006 and (EU) No 255/2010 Text with EEA relevance
- ^ a b Manual of Air Traffic Services Part 1
- ^ "Car 602.115". 6 March 2022.
- ^ "CAR 602.114".
- ^ "CAR 602.114 (d)(ii)".
- ^ a b c 14 CFR 91.155