Airspace—Weather Minimums
§ 91.155 Basic VFR weather minimums. [Link]
(a) Except as provided in paragraph (b) of this section and §91.157, no person may operate an aircraft under VFR when the flight visibility is less, or at a distance from clouds that is less, than that prescribed for the corresponding altitude and class of airspace in the following table:
| Airspace | Flight visibility | Distance from clouds |
|---|---|---|
| Class A | Not Applicable | Not Applicable. |
| Class B | 3 statute miles | Clear of Clouds. |
| Class C | 3 statute miles | 500 feet below. 1,000 feet above. 2,000 feet horizontal. |
| Class D | 3 statute miles | 500 feet below. 1,000 feet above. 2,000 feet horizontal. |
| Class E: | ||
| Less than 10,000 feet MSL | 3 statute miles | 500 feet below. 1,000 feet above. 2,000 feet horizontal |
| At or above 10,000 feet MSL | 5 statute miles | 1,000 feet below. 1,000 feet above. 1 statute mile horizontal. |
| Class G: | ||
| 1,200 feet or less above the surface (regardless of MSL altitude) | ||
| Day, except as provided in §91.155(b) | 1 statute mile | Clear of clouds. |
| Night, except as provided in §91.155(b) | 3 statute miles | 500 feet below. 1,000 feet above. 2,000 feet horizontal. |
| More than 1,200 feet above the surface but less than 10,000 feet MSL | ||
| Day | 1 statute mile | 500 feet below. 1,000 feet above. 2,000 feet horizontal. |
| Night | 3 statute miles | 500 feet below. 1,000 feet above. 2,000 feet horizontal. |
| More than 1,200 feet above the surface and at or above 10,000 feet MSL | 5 statute miles | 1,000 feet below. 1,000 feet above. 1 statute mile horizontal. |
(b) Class G Airspace. Notwithstanding the provisions of paragraph (a) of this section, the following operations may be conducted in Class G airspace below 1,200 feet above the surface:
(1) Helicopter. A helicopter may be operated clear of clouds if operated at a speed that allows the pilot adequate opportunity to see any air traffic or obstruction in time to avoid a collision.
(2) Airplane, powered parachute, or weight-shift-control aircraft. If the visibility is less than 3 statute miles but not less than 1 statute mile during night hours and you are operating in an airport traffic pattern within 1/2mile of the runway, you may operate an airplane, powered parachute, or weight-shift-control aircraft clear of clouds.
(c) Except as provided in §91.157 [Special VFR], 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.
(d) Except as provided in §91.157 [Special VFR] of this part, no person may take off or land an aircraft, or enter the traffic pattern of an airport, under VFR, within the lateral boundaries of the surface areas of Class B, Class C, Class D, or Class E airspace designated for an airport—
(1) Unless ground visibility at that airport is at least 3 statute miles; or
(2) If ground visibility is not reported at that airport, unless flight visibility during landing or takeoff, or while operating in the traffic pattern is at least 3 statute miles.
(e) For the purpose of this section, an aircraft operating at the base altitude of a Class E airspace area is considered to be within the airspace directly below that area.
Summary
I like to organize the information a bit differently. In the table below, Class E altitudes are MSL. Class G are AGL. The notation, Class E10,000— means Class E airspace up to but not including 10,000′ MSL. The notation Class G1,200+ means Class G airspace above 1,200′ AGL.
| Airspace | Flight visibility | Distance from clouds |
|---|---|---|
| Class A | N/A IFR Rules Apply | N/A IFR Rules Apply |
| Class B | 3 statute miles | COC |
| Class C, Class D Class E10,000—, Class GNight |
3 statute miles | 1,000′ | 2,000′ 500′ | |
| ≥ 10,000′ MSL Class E, Class G1,200+ |
5 statute miles | 1,000′ | 1 mile 1,000′ | |
| Class G—more than 1,200 AGL and less than 10,000 MSL | 1 statute mile | 1,000′ | 2,000′ 500′ | |
| Class G ≤ 1,200 AGL | 1 statute mile | COC |
| Airspace | Flight visibility | Ceiling |
|---|---|---|
| Class B, C, D, E surface area | 3 statute miles | 1,000′ |
| Class G1,200— Night—within 1/2 mile of runway | 1 statute mile | COC |
| Special VFR—Class B, C, D, E surface area and 10,000— | 1 statute mile | COC |
| Special VFR at Night—Plane and pilot must be IFR rated | 1 statute mile | COC |
Rod Machado has another way of looking at airspace.