Pilot Counsel

VFR weather minimums, part II

December 1, 2005

AOPA's legal counsel John S. Yodice has been writing this column for AOPA Pilot since 1965.

Last month we reviewed in detail what we call the "standard" VFR weather minimums (see " Pilot Counsel: VFR Weather Minimums, Part I," November Pilot). This is a simplified, but still accurate, version of the very complicated minimums set out in FAR 91.155. In last month's column we recommended that all pilots memorize at least these "standard" VFR weather minimums. 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. Yet, if a pilot sometimes wants the benefit of lower, less stringent minimums that are available in some airspace for some particular operations, then he or she can concentrate on the ones desired without having to memorize all of the other nonstandard (and complicating) minimums.

So this month we will review the VFR minimums that are different from this standard set — some are higher, or more stringent, than the standard set; some are lower, or less stringent. These differences make the complete set of VFR minimums complicated. As we identify the types of operations where you could operate with less-than-standard minimums, we will provide the regulatory references in case you would like to make a finer analysis.

Class G 'uncontrolled' airspace

Probably the differences of greatest importance to most pilots are the ones that apply in uncontrolled airspace below 10,000 feet msl. It is surprising that there is still quite a bit of uncontrolled airspace in this country. Uncontrolled airspace, officially called Class G airspace, can be identified by the coding on VFR charts. What is sometimes missed is the uncontrolled airspace underneath the floors of controlled airspace. The coding needs to be studied carefully. This uncontrolled airspace can be found in some heavily trafficked areas. As we will see, in uncontrolled airspace we may often operate with as little as one-mile visibility and/or clear of clouds. This is especially true during the daytime and at low altitudes.

Daytime. During the daytime, we may operate VFR anywhere in Class G airspace with as little as one-mile visibility. However, the standard cloud clearance minimums still apply (500 below, 1,000 above, 2,000 horizontally), except in low-level operations at or below 1,200 feet agl. At these low levels during the daytime the minimum is "clear of clouds." This also is true even in mountainous areas where these low levels at or below 1,200 feet agl are, in fact, above 10,000 feet msl.

Nighttime. At nighttime, however, regardless of altitude, the standard minimums for both visibility and cloud clearance apply — with one narrow exception that is important to some pilots. That exception relates to nighttime operations at airports in uncontrolled airspace. When 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.

Too complicated? Remember that observing the simplified standard VFR minimums will keep you in automatic compliance.

Class B airspace

This is a difference that at first seems strange. It reduces the standard cloud clearance requirements in the most congested of airspace — the Class B airspace overlying our busiest air-carrier airports. In Class B airspace, while the standard three-mile visibility minimum still applies (and ground visibility will be officially reported and is binding on pilots), the cloud clearance requirement is reduced to "clear of clouds."

This difference actually does make sense. Air traffic control provides separation service to all aircraft in Class B airspace, including VFR aircraft. Remember, it is the VFR pilot's obligation to remain in VFR conditions at all times. If pilots had to observe the standard VFR cloud clearance requirements (500/1,000/2,000 feet clearance), for example, by refusing radar vectors that would get them too near to clouds, this could unnecessarily complicate the ATC situation. The saving feature is that ATC is keeping even the VFR aircraft clear of other traffic. The reduced cloud clearance requirement allows VFR aircraft to follow ATC radar vectors and routings with less chance of deviation because of nearby clouds. "Clear of clouds" still must be observed, however.

Special VFR

Along with the reduced minimums in uncontrolled airspace, the reduced minimums available in a Special VFR operation are important to many pilots. The "Special VFR weather minimums" are set out in a separate section of the regulations, FAR 91.157, as opposed to everything else we have been talking about — which is set forth in FAR 91.155 under the heading of "Basic VFR weather minimums." Note again that "basic" and "special" are terms in the rules. "Standard" is a term, not in the rules, that I use for convenience in explaining the rules.

Ordinarily, within the lateral boundaries of the controlled airspace that begins at the surface of an airport, the standard VFR weather minimums apply. That's class B, C, and D airspace, as well as the Class E airspace that begins at the surface of the airport (not an airport that has Class G airspace at its surface with Class E airspace above). 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. Special VFR is frequently, and safely, used to get into and out of an airport when local weather conditions have slipped below standard VFR.

For Special VFR operations between the time of sunset and sunrise (loosely "night"; see " Pilot Counsel: Night Flying and the FARs," October Pilot), 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 some 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.

Helicopters

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 as 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.

At or above 10,000 feet msl

There is only one set of minimums in FAR 91.55 that is higher — that is, more stringent — than the 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.

But, as we have already mentioned, 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 not only less than these, but even less than the standard minimums, as we explained above.

Student, recreational, and sport pilots

Student, recreational, and sport pilots have additional weather restrictions placed on them by FAR Part 61. Their visibility (flight or surface) minimums are three statute miles in the daytime and five statute miles at night (a sport pilot may not operate at night). Also, they cannot operate without visual reference to the surface — no "over the top" operations. These restrictions are in FAR 61.89(a)(6) and (7) for students, FAR 61.101(d)(9) and (10) and (h)(3) for recreational pilots, and FAR 61.315(c)(5), (12), and (13) for sport pilots.

John S. Yodice