VFR weather minimums cheat sheet: 14 CFR 91.155 by class of airspace

The pattern behind the table

Most controlled airspace below 10,000 feet MSL uses the same numbers: 3 statute miles of flight visibility, and 500 feet below, 1,000 feet above and 2,000 feet horizontally from clouds. Remember that one line and the exceptions become easy to spot.

Class B is simpler, because ATC separates every aircraft in it: 3 statute miles and clear of clouds. At or above 10,000 feet MSL, where speeds are higher, the requirement grows to 5 statute miles and 1,000 feet below, 1,000 feet above and 1 statute mile horizontally from clouds.

• Class A: VFR flight is not permitted; every operation is IFR.
• Class B: 3 SM, clear of clouds.
• Class C and Class D: 3 SM; 500 below, 1,000 above, 2,000 horizontal.
• Class E below 10,000 MSL: 3 SM; 500 below, 1,000 above, 2,000 horizontal.
• Class E at or above 10,000 MSL: 5 SM; 1,000 below, 1,000 above, 1 SM horizontal.

Class G, where day and night differ

Uncontrolled airspace is where the test likes to catch people, because the minimums depend on both altitude above the surface and time of day.

At 1,200 feet or less above the surface, an airplane needs 1 statute mile and clear of clouds by day, but 3 statute miles and 500 below, 1,000 above, 2,000 horizontal at night. One exception: at night, an airplane in the traffic pattern within half a mile of the runway may operate clear of clouds with at least 1 statute mile of visibility.

• 1,200 AGL or less, day: 1 SM, clear of clouds.
• 1,200 AGL or less, night: 3 SM; 500-1,000-2,000 (1 SM clear of clouds in the pattern within 1/2 mile of the runway).
• Above 1,200 AGL, below 10,000 MSL, day: 1 SM; 500-1,000-2,000.
• Above 1,200 AGL, below 10,000 MSL, night: 3 SM; 500-1,000-2,000.
• Above 1,200 AGL and at or above 10,000 MSL: 5 SM; 1,000-1,000-1 SM.

Surface areas and special VFR

Within the surface area of Class B, C, D or E airspace designated for an airport, 91.155 adds two conditions: no VFR flight beneath the ceiling when the ceiling is less than 1,000 feet, and no takeoff, landing or traffic pattern entry unless ground visibility is at least 3 statute miles (or flight visibility, if ground visibility is not reported).

When the weather is below that, special VFR under 14 CFR 91.157 may be available with an ATC clearance: the pilot must remain clear of clouds with at least 1 statute mile of flight visibility. At night, special VFR requires an instrument-rated pilot in an airplane equipped for instrument flight.

How the test asks it

Questions usually give an altitude, a class of airspace and a time of day, sometimes by pointing at a sectional chart excerpt from the FAA testing supplement, and ask for the visibility or cloud clearance. Identify the airspace first, including where the Class E floor is, then decide day or night, then read the numbers.