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.
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.
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.
[4]Maintain at least 500 feet AGL except when taking off or landing.
[5]VFR flight prohibited in Class A airspace.United States Visual Flight Rules are provided in Title 14 of the Code of Federal Regulations, Part 91, Section 155:[6]