Cloud clearance and VFR references

What this reference shows

This reference summarizes selected United States basic VFR weather minimums in 14 CFR 91.155. Choose an airspace class, day or night, altitude above mean sea level, and height above the surface to see the applicable flight-visibility and cloud-clearance values represented by this tool.

The output is a minimum reference, not a weather report. It does not determine whether the aircraft is in the selected class of airspace, measure cloud distance, or establish that a flight is legal or safe. Pilots must identify the actual airspace and consider all other applicable requirements.

How to use the reference

Airspace class. Select the class in which the aircraft is operating. The tool includes Classes B, C, D, E, and G. It does not calculate Class A operations or identify airspace boundaries.

Time. Select day or night for the Class G rules. Under the general definition in 14 CFR 1.1, night is the period between the end of evening civil twilight and the beginning of morning civil twilight. Other aviation rules can use different time definitions.

Altitude MSL. Enter altitude above mean sea level. The 10,000-foot threshold in the Class E and Class G rules is based on MSL.

Height AGL. Enter height above the surface. The 1,200-foot threshold for the lower Class G rules is based on AGL. If the aircraft is operating in Class G, both altitude references may be needed to identify the correct row.

Basic minimums represented

In Class B, the basic minimum is 3 statute miles flight visibility and clear of clouds. In Class C, D, and E airspace below 10,000 feet MSL, the basic minimum is 3 statute miles, 500 feet below clouds, 1,000 feet above, and 2,000 feet horizontally.

For Class E at or above 10,000 feet MSL, the basic minimum is 5 statute miles and cloud distances of 1,000 feet below, 1,000 feet above, and 1 statute mile horizontally. The Class G rules use different visibility minimums by altitude and time of day.

In Class G at or below 1,200 feet AGL during the day, the basic minimum is 1 statute mile and clear of clouds. At night in that low-level band, the minimum is 3 statute miles with 500 feet below, 1,000 feet above, and 2,000 feet horizontally. Above 1,200 feet AGL and below 10,000 feet MSL in Class G, the cloud distances remain 500, 1,000, and 2,000 feet; visibility is 1 statute mile by day and 3 statute miles at night. At or above 10,000 feet MSL in Class G, the minimum is 5 statute miles and 1,000 feet below, 1,000 feet above, and 1 statute mile horizontally.

The exact text, exceptions, and applicability are in 14 CFR 91.155. Consult the current regulation rather than relying on this summary.

Interpreting the result

The visibility value is flight visibility, meaning visibility from the cockpit in the direction of flight. It is not automatically the same as surface visibility reported at an airport. Cloud-clearance values describe required separation from clouds; "clear of clouds" is a distinct standard and is not a numerical distance.

For example, a daytime operation in Class G at 800 feet AGL and below 10,000 feet MSL displays 1 statute mile and clear of clouds. At night with the same altitude values, it displays 3 statute miles and the stated vertical and horizontal cloud distances.

Other VFR requirements to review

Weather minimums are only one part of VFR requirements. Airspace entry rules, required clearances, equipment, visibility, and operating limitations may also apply. Special VFR is a separate authorization with its own requirements in 14 CFR 91.157; it is not calculated here.

The reference does not compare the minimums with observed weather. A METAR's reported visibility and cloud groups describe conditions at an observation location and time. They do not by themselves establish flight visibility or cloud separation along a route. Obtain current weather information and interpret it with the applicable regulations, charts, and conditions.

Common interpretation errors

Do not use AGL where a rule specifies MSL, or MSL where it specifies height above the surface. In this summary, Class G's 1,200-foot boundary is AGL, while the 10,000-foot boundary is MSL. A high-elevation airport can make those references differ substantially.

Do not treat "clear of clouds" as a synonym for a measured distance. It is a separate condition used in the listed low-level Class G daytime and Class B rules. The numerical rows instead specify vertical and horizontal separation.

Limitations and other rules

This is a selected basic-minimums summary for fixed-wing reference. It does not include special VFR authorization under 14 CFR 91.157, helicopter provisions, flight visibility exceptions, airspace-specific authorizations, or all requirements that may apply near airports, controlled airspace, or special use airspace. It does not interpret clearances, local procedures, NOTAMs, or current weather.

Airspace class can change with altitude and location. Confirm the aircraft's position and the applicable chart before interpreting a class-based reference. If any condition is uncertain, use current official sources and obtain appropriate instruction. The tool does not provide an operational flight decision.

Sources and methodology

The minimums are transcribed as a concise reference from 14 CFR 91.155. Definitions and exceptions remain governed by current regulations and FAA publications. The tool contains no live weather or airspace data.

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