Visual flight rules
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- "VFR" redirects here. For , see .
Visual flight rules (VFR) are a set of aviation regulations under which a pilot may operate an aircraft, if weather conditions are sufficient to allow the pilot to visually control the aircraft's attitude, navigate, and maintain separation with obstacles such as terrain and other aircraft.
Pilots flying under VFR assume responsibility for their separation from all other aircraft and are not assigned routes or altitudes by ATC (outside of positive control airspace). They fly on their own using a "see and be seen" separation criteria. In busier controlled airspace, VFR aircraft are required to have a transponder. This amplifies the radar signal (as well broadcasting altitude level and a transponder code), and is used to allow controllers to warn instrument flight rules (IFR) aircraft of any potential conflict. Governing agencies establish strict VFR "weather minima" for visibility, distance from clouds, and altitude to ensure that VFR pilots can be seen from a far enough distance.
VFR pilots can request, and ATC can elect to provide "VFR Advisory Services," if the controllers' workload permits. This is also referred to as "Flight following." Under this environment, the controllers will radar identify the VFR aircraft and provide traffic information and weather advisory services for the VFR pilot. Controllers do not provide any instructions concerning direction of flight, altitude, or speed to the VFR pilot receiving advisory services (unless an urgent, potentially hazardous situation arises -- at such a time, the controller may elect to provide directions to resolve the conflict), and they do not provide separation services. This is an optional service and may be discontinued by ATC or the pilot at any time.
The minimum meteorological requirements for VFR are called visual meteorological conditions (VMC) minima. If they are not met then the flight must be flown under IFR, the pilot must have an instrument rating and meet recency of experience requirements pertaining to instrument flight, and the aircraft must be equipped and type-certified for instrument flight. In some types of airspace, generally at higher altitudes, a flight must be flown under IFR regardless of the meterological conditions, as aircraft fly at high speeds at higher altitudes and the "see and avoid" method of avoiding conflicting traffic is less successful.
See also
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