Pilot Counsel: VFR weather minimums, Part II

Reviewing the less-stringent minimums

July 1, 2013

John S. YodiceLast month we reviewed what I call the “standard” VFR weather minimums (“Pilot Counsel: VFR Weather Minimums, Part I,” June AOPA Pilot). They are: visibility of 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. The benefit of this simplified version is that in all of our national airspace below 10,000 feet msl (which is where most VFR flying happens), a pilot who complies with the “standard” minimums will be in automatic compliance with FAR 91.155. This month we get to the more complicated but happily lower, less stringent, minimums that are available in some airspace for some particular operations.

Probably the less-stringent minimums of greatest importance to most pilots are those that apply in uncontrolled airspace—that is, Class G airspace, below 10,000 feet msl. During the daytime, we may operate VFR anywhere in Class G airspace with as little as one mile visibility. The “standard” cloud clearance minimums still apply (500 below, 1,000 above, 2,000 horizontally) but are reduced in operations at or below 1,200 feet agl to clear of clouds. At nighttime, regardless of altitude, the standard minimums for both visibility and cloud clearance apply—with one narrow exception for low-level nighttime operations at airports in uncontrolled airspace. Operating an airplane in the traffic pattern of an airport in uncontrolled airspace, even at night, the minimums are one mile visibility and clear of clouds. To have the advantage of these lower minimums at night, the airplane must operate at or below 1,200 feet agl and remain within one-half mile of the runway.

Along with the reduced minimums in uncontrolled airspace, reduced minimums are available in Special VFR operations as set out in FAR 91.157. Ordinarily, within the lateral boundaries of the controlled airspace that begins at the surface of an airport, the standard VFR weather minimums apply. However, in that controlled airspace, if a Special VFR clearance is first obtained from the controlling ATC facility that has jurisdiction of the airspace, the Special—and not the standard—VFR minimums will apply. The Special VFR weather minimums are quite a bit lower than standard: one statute mile visibility and clear of clouds.

For Special VFR operations between the time of sunset and sunrise (loosely “night”), the pilot must be rated and current for instrument flight and the aircraft must be equipped for instrument flight. (In Alaska, the instrument requirement applies when the sun is 6 degrees or more below the horizon). While a Special VFR clearance may be obtained at many airports, it is not permitted for fixed-wing aircraft at 33 specifically identified airports; they are indicated on visual charts and in aeronautical publications. As you would guess, they are the airports with the highest traffic density.

There is a lower minimum in Class B airspace that at first seems strange. Class B airspace overlies our busiest air-carrier airports, yet the standard cloud-clearance requirements are reduced to clear of clouds. The standard three-mile visibility minimum still applies.

Helicopters, in general, must comply with the standard VFR weather minimums. However, their unique flight characteristics allow less-stringent minimums at low altitudes in uncontrolled airspace, and under Special VFR. Below 1,200 feet agl in Class G airspace or when operating under Special VFR, a helicopter may be operated clear of clouds without a numerical visibility minimum so long as it is operated at a speed that allows the pilot to see any air traffic or obstruction in time to avoid a collision. For Special VFR at night, helicopter pilots do not have to be instrument-rated and the helicopter does not have to be equipped for IFR.

There is only one set of minimums in FAR 91.155 that are higher—that is, more stringent—than my standard minimums. Those are the minimums that apply at and above 10,000 feet msl. In that airspace, the flight visibility must be at least five statute miles and the required cloud clearance must be at least 1,000 feet below, 1,000 feet above, and one statute mile horizontally. These increased minimums have not proven troublesome to VFR pilots operating at the middle altitudes. However, there are unique situations in mountainous areas where it is possible to be operating at or below 1,200 feet agl and still be above 10,000 feet msl. In those circumstances, we can get the benefit of minimums less than the standard—daytime, one mile and clear of clouds; nighttime, three miles and standard cloud clearance, except lower for nighttime operations in a close-in traffic pattern of an airport, explained above.

John S. Yodice owns a Cessna 310 and flies from his home base at the Frederick Municipal Airport (FDK) in Maryland. Visit his website.