Helicopter VFR Weather Minimums

Reference: 14 CFR 91.155 and 14 CFR 91.157

VFR weather minimums are the flight visibility and cloud clearance values you must have to operate under visual flight rules. They change with the class of airspace and with your altitude, and in one specific case they change because you are flying a helicopter rather than an airplane.

That last point is where most of the confusion lives. Helicopters get exactly one break in 91.155, and it is narrower than most pilots remember. Everywhere else, you fly the same numbers as everyone else.

Quick reference

The helicopter exception and its limits

In Class G airspace at 1,200 feet AGL or below, a helicopter may operate in 1/2 statute mile visibility during the day and 1 statute mile at night, clear of clouds in both cases.

Two things to hold onto:

It is tied to altitude, not to the aircraft. Climb above 1,200 AGL and the relief disappears. In Class G above 1,200 AGL you are back to 1 SM day and 3 SM night with standard 500, 1,000, 2,000 cloud clearance, exactly like an airplane. This catches people. Scud running at 500 feet in 3/4 of a mile is legal in Class G; climbing to 1,500 feet in the same conditions is not.

It is tied to Class G, not to being low. Being 500 feet AGL does not help you if that airspace is Class E to the surface or a Class D surface area. The class of airspace governs.

There is also a separate allowance in 91.155(b)(1). A helicopter may operate clear of clouds in an airport traffic pattern within 1/2 mile of the runway or helipad of intended landing, in Class G below 1,200 AGL, with flight visibility of not less than 1/2 statute mile. That paragraph carries no day or night restriction, so it is the provision that lets you work the pattern in 1/2 mile at night.

Class G (uncontrolled)

Class G is airspace that has not been designated as Class A, B, C, D, or E. It is the default, and it is what remains underneath controlled airspace.

The common shorthand that Class G always ends at 1,200 AGL is not correct. Class E floors vary. Class E begins at the surface inside a designated surface area, at 700 AGL under the shaded magenta transition areas, at 1,200 AGL along the edges of the shaded blue areas, and at a published MSL altitude in some locations. In parts of the western United States, Class G can extend up to 14,500 MSL.

Class G is not charted directly. You identify it by reading the Class E floors around it and working out what is left. Knowing where the Class E floor actually sits over your route is a preflight item, not a guess.

Minimums are in the table above. The 1,200 AGL break in that table is a fixed reference to height above the surface, and it applies whether or not the Class E floor above you happens to sit at 1,200 AGL.

Class E (controlled)

Class E is controlled airspace that is not Class A, B, C, or D. It supports instrument approaches, airways, and the transition of IFR traffic between the terminal and en route environments.

Class E floors vary as described above. It extends up to but not including 18,000 MSL, and it also exists above FL600.

Below 10,000 MSL you need 3 SM with 500, 1,000, and 2,000 foot cloud clearance. At or above 10,000 MSL that increases to 5 SM with 1,000 below, 1,000 above, and 1 statute mile horizontal. The 10,000 MSL step is a common oversight for anyone operating in high terrain.

Special VFR is available in a Class E surface area with a clearance from the controlling facility. It is not available in Class E airspace generally, and it is not available in the extension areas that run off a surface area.

Class D (controlled)

Surface up to and including 2,500 feet above the airport elevation, charted in MSL and rounded to the nearest 100 feet, surrounding airports with an operating control tower that do not have the traffic volume for Class C. Each Class D is tailored to the airport it serves.

3 SM visibility, 500 feet below, 1,000 feet above, 2,000 feet horizontal.

Class D exists only while the tower is operating. When the tower closes, the airspace typically reverts to a Class E surface area or to Class G, and the applicable minimums change with it. Check the Chart Supplement for the airport you are using.

Class C (controlled)

Generally a 5 NM radius core from the surface to 4,000 feet above airport elevation, plus a shelf from 5 to 10 NM extending from 1,200 feet to 4,000 feet above airport elevation, charted in MSL. Established at airports with a radar approach control and a qualifying volume of IFR operations. Each Class C is tailored to its airport.

3 SM visibility, 500 feet below, 1,000 feet above, 2,000 feet horizontal.

Class B (controlled)

Surface to 10,000 MSL surrounding the nation's busiest airports, individually tailored and typically built in layered shelves.

3 SM visibility and clear of clouds. There is no numerical cloud clearance requirement in Class B, because ATC is separating all traffic inside it.

An ATC clearance to enter is required. "Cleared into the Class Bravo" is the phrase. Two-way communication alone is not enough.

Class A (controlled)

18,000 MSL up to and including FL600. IFR only, so VFR weather minimums do not apply. Not charted, since it blankets the entire country above 18,000 MSL.

Three rules that are not in the table

These live in the rest of 91.155 and are missed more often than the visibility numbers.

The 1,000 foot ceiling rule, 91.155(c). You may not operate 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. Reported visibility can be perfectly legal and this rule will still stop you. Special VFR is the relief.

The 3 SM ground visibility rule, 91.155(d). You may not take off, land, or enter the traffic pattern under VFR within a Class B, C, D, or E surface area unless ground visibility at that airport is at least 3 SM. If ground visibility is not reported, flight visibility during takeoff, landing, or pattern work must be at least 3 SM. Again, Special VFR is the relief.

The base altitude rule, 91.155(e). An aircraft operating at the base altitude of a Class E area is considered to be in the airspace directly below it. Level at exactly 1,200 AGL under a 1,200 foot Class E floor, you are in Class G.

Special VFR

Reference: 14 CFR 91.157

Special VFR is an ATC clearance that lets you operate in a surface area when the weather is below basic VFR minimums. For helicopter pilots it is the single most useful tool in 91.155 and 91.157 combined, and it is also the most widely misunderstood.

Where it is available. Class B, C, D, and E surface areas only, below 10,000 MSL. It is not available in Class A, it is not available in Class E airspace away from a surface area, and it is prohibited outright at the airports listed in Part 91 Appendix D, Section 3, which are marked "NO SVFR" on sectional charts.

What 91.157 requires. There are four conditions:

1. An ATC clearance.
2. Remain clear of clouds.
3. Flight visibility of at least 1 statute mile, except for helicopters.
4. Between sunrise and sunset, except for helicopters, or with an instrument rated pilot in an aircraft equipped for IFR under 91.205(d).

For a fixed-wing aircraft other than a helicopter, 91.157(c) additionally prohibits takeoff and landing unless ground visibility is at least 1 SM, or flight visibility is at least 1 SM if ground visibility is not reported. Helicopters are excluded from that too.

You have to ask for it. ATC will not offer Special VFR. FAA Order JO 7110.65 paragraph 7-5-1 authorizes it only on pilot request. Controllers are specific about this, because requesting it is how you tell them you have judged the conditions acceptable.

It is not first come, first served against IFR traffic. Paragraph 7-5-2 permits Special VFR only when arriving and departing IFR aircraft are not delayed. Expect a delay advisory rather than an expect further clearance time.

The helicopter visibility question

Helicopters are excluded from the 1 statute mile visibility requirement in 91.157. There is no regulatory visibility floor for a helicopter operating under Special VFR.

That is a legal fact and a terrible operating philosophy. The regulation still requires you to remain clear of clouds, which you cannot reliably do in visibility you do not have, and Part 135 operators, company op specs, and any competent set of personal minimums all sit well above zero. Treat the absence of a number as the FAA declining to write one for a category of aircraft that can slow down and land almost anywhere, not as an endorsement of launching into fog.

Correction: the "only one aircraft" myth

An earlier version of this page listed "are the only aircraft at the airport operating under SVFR" as a condition of Special VFR. That was incorrect, and it has been removed.

There is no such restriction in 91.157, and AIM 4-4-6 contradicts it directly by stating that ATC provides separation between Special VFR flights. FAA Order JO 7110.65 paragraph 7-5-3 goes further and specifies which separation methods controllers apply between two Special VFR aircraft, including a reduced minimum of 200 feet between helicopters departing simultaneously on diverging courses under a letter of agreement.

Some individual facilities do run one Special VFR aircraft at a time as a matter of local practice. That is a facility decision, not a regulation, and it does not transfer to the next airport.

We have written up how that misconception formed, and how to trace a claim like it through the CFR, the AIM, and the controller's manual, in a separate article.

Part 135 and company minimums

Everything above is Part 91. If you fly commercially, Part 135 imposes its own VFR weather minimums, and your operator's op specs may impose more restrictive numbers still. HEMS operations in particular carry additional requirements. Part 91 is the floor beneath your operation, not the number you plan to.