How to be sure ou're in compliance
Three weather phenomena must be considered in determining whether a flight may be conducted under VFR below 10,000 feet msl: visibility, cloud clearance, and ceiling.
Visibility. In Classes B, C, D, and E airspace, visibility must be three statute miles, day and night, for VFR flight. In Class G airspace, a pilot must have visibility of at least one statute mile during the day and three statute miles at night. However, an exception to the Class G night visibility requirement permits flight if the visibility is at least one statute mile and the pilot stays in the airport traffic pattern within one-half mile of the runway and remains clear of clouds.
There is a distinction between ground and flight visibility that could affect whether a pilot may conduct the flight. Ground visibility is defined in FAR Part 1 as "the prevailing horizontal visibility near the Earth's surface as reported by the United States National Weather Service or an accredited observer." If an airport within controlled airspace officially reports weather, a pilot taking off, landing at, or entering the traffic pattern at that airport is bound by the officially reported ground visibility.
Otherwise, the visibility minimums refer to flight visibility, defined as the average forward visibility observed by the pilot from the cockpit. So, an aircraft transiting controlled airspace, but not operating at the airport, must maintain the proper flight visibility minimums but is not bound by the officially reported ground visibility.
Cloud clearances. In Class B airspace, day and night, a pilot operating under VFR must remain clear of clouds. In Classes C, D, and E airspace, day and night, the pilot must remain 500 feet below, 1,000 feet above, and 2,000 feet horizontally from any cloud. The cloud clearance limits change for Class G airspace, depending on how far above the surface you are and whether it is day or night. More than 1,200 feet above the surface, day and night -- and below that altitude at night -- the pilot must remain 500 feet below, 1,000 feet above, and 2,000 feet horizontally from any cloud. Below 1,200 feet above the surface during the day, the pilot must remain clear of clouds.
Ceiling. The ceiling minimum applies only to airports in controlled airspace. The rule states that "no person may operate an aircraft beneath the ceiling under VFR within the lateral boundaries of controlled airspace designated to the surface for an airport when the ceiling is less than 1,000 feet." This ceiling restriction does not apply to flights in uncontrolled airspace. Note that the rule is that an aircraft may not operate VFR beneath a reported ceiling when the ceiling is less than 1,000 feet. An aircraft may operate VFR above a reported ceiling, "on top," even while passing right over the airport.
FAR Part 61 places additional weather restrictions on student, recreational, and sport pilots. During daylight hours, student, recreational, and sport pilots may not act as pilot in command of an aircraft with flight or surface visibility of fewer than three statute miles. At night, student and recreational pilots may not act as PIC with flight or surface visibility of fewer than five statute miles. For recreational pilots, the nighttime restrictions apply from sunset to sunrise. Sport pilots are prohibited from acting as PIC of a light-sport aircraft at night. And, student, recreational, and sport pilots may not command a flight if the flight cannot be made with visual reference to the surface -- no "on-top operations" permitted.
It's easy to be sure you're in compliance with the VFR cloud clearance, ceiling, and visibility limits below 10,000 feet by remembering one set of three minimums: visibility of at least three statute miles; cloud clearance of 500 feet below, 1,000 feet above, and 2,000 feet horizontally; and a ceiling of at least 1,000 feet above the surface.
For flights above 10,000 feet msl, the limits for VFR flight are fairly standard. In Class E airspace, a pilot must have a flight visibility of five statute miles and must remain 1,000 feet below, 1,000 feet above, and one statute mile horizontally from any cloud. In Class G airspace, above 10,000 feet msl, and more than 1,200 feet above the surface, a pilot must have a flight visibility of five statute miles and must remain 1,000 feet below, 1,000 feet above, and one statute mile horizontally from any cloud.
Kathy Yodice is an attorney with Yodice Associates in Washington, D.C., which provides legal counsel to AOPA and administers AOPA's legal services plan. She is an instrument-rated private pilot.
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