Visual flight rules
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"VFR" redirects here. For other uses, see VFR (disambiguation).
Visual flight rules (VFR) are a set of aviation regulations under which a pilot may operate an aircraft in weather conditions sufficient to allow the pilot, by visual reference to the environment outside the cockpit, to control the aircraft's attitude, navigate, and maintain safe separation from obstacles such as terrain, buildings, and other aircraft.
The essential collision safety principle guiding the VFR pilot is "see and avoid". Pilots flying under VFR assume responsibility for their separation from all other aircraft and are generally not assigned routes or altitudes by air traffic control. In busier controlled airspace, VFR aircraft are required to have a transponder. Governing agencies establish strict VFR "weather minima" for visibility, distance from clouds, and altitude to ensure that aircraft operating under VFR can be seen from a far enough distance to ensure safety.
In strictly controlled airspace, air traffic control will separate VFR aircraft from all other aircraft or just from instrument flight rules (IFR) aircraft. In other airspace, a VFR pilot can at his or her discretion request advisory service from air traffic control regarding other aircraft in their vicinity, but the duty of maintaining safe separation still remains with the pilot.
The minimum meteorological requirements for VFR are termed visual meteorological conditions (VMC). If they are not met then the flight must operate under IFR; to do so, the pilot must hold an instrument rating and meet recency of experience requirements pertaining to instrument flight, the aircraft must be equipped and type-certified for instrument flight, and the flight must have a clearance to operate under IFR from air traffic control. In some types of airspace, generally at higher altitudes, a flight must operate instrument flight rules regardless of the meteorological conditions, as aircraft fly at high speeds at higher altitudes and thus the "see and avoid" method of avoiding conflicting traffic is not adequate to ensure safety.
[edit] Controlled Visual Flight Rules
CVFR flight is used in locations where aviation authorities have determined that VFR flight should be allowed, but that ATC separation minima and guidance are necessary. In this respect, CVFR is similar to Instrument flight rules (IFR) in that ATC will give pilots headings and altitudes at which to fly, and will provide separation and conflict resolution. However, pilots and aircraft do not need to be IFR rated to fly in CVFR areas, which is highly advantageous. An example of airspace where CVFR is common would be Canadian Class B airspace.
The CVFR concept is used in Canada and certain European countries, but not in the U.S., where the Private Pilot certificate itself authorizes the pilot to accept clearances under VFR.
