Class B
3 SM and clear of clouds.
Interactive table
Build the minimum.
Select the operating environment. The rule card and cloud-clearance picture update together.
1 · Airspace class
3 · Time of day
Aircraft category is fixed to airplane throughout this guide.
Class B airspace
3 SM · CLEARThree and clear
Maintain at least 3 statute miles of flight visibility and remain clear of clouds.
Flight visibility3 SM
Below cloudsClear
Above cloudsClear
HorizontalClear
Clear
Clear
Clear
●
Operational cueCloud distance is not numerically specified, but “clear of clouds” still requires the airplane to remain outside the cloud.
Memory aid
Four anchors, then add context.
Use these as retrieval cues. The complete table and operational limitations remain the controlling reference.
The familiar controlled rule
3 SM, 1,000 above, 500 below, 2,000 horizontal. Applies in C, D, and E below 10,000 MSL.
High-altitude rule
5 SM, 1,000 above, 1,000 below, 1 SM horizontal at or above 10,000 MSL.
Class G changes
Check the AGL/MSL band, then day or night. Low daytime G is the least restrictive: 1 SM and clear.
Reference table
See every airplane rule together.
Distances are shown in the same below, above, and horizontal order used in the regulation’s table.
14 CFR § 91.155 airplane summarySM = statute miles · MSL = mean sea level · AGL = above ground level
| Airspace / altitude | Time | Flight visibility | Below cloud | Above cloud | Horizontal |
|---|---|---|---|---|---|
| Class A | Any | Not applicable | |||
| Class B | Any | 3 SM | Clear of clouds | ||
| Class C | Any | 3 SM | 500 ft | 1,000 ft | 2,000 ft |
| Class D | Any | 3 SM | 500 ft | 1,000 ft | 2,000 ft |
| Class E below 10,000 ft MSL | Any | 3 SM | 500 ft | 1,000 ft | 2,000 ft |
| Class E at or above 10,000 ft MSL | Any | 5 SM | 1,000 ft | 1,000 ft | 1 SM |
| Class G, 1,200 ft AGL or less | Day | 1 SM | Clear of clouds | ||
| Class G, 1,200 ft AGL or less | Night | 3 SM | 500 ft | 1,000 ft | 2,000 ft |
| Class G, above 1,200 ft AGL and below 10,000 ft MSL | Day | 1 SM | 500 ft | 1,000 ft | 2,000 ft |
| Class G, above 1,200 ft AGL and below 10,000 ft MSL | Night | 3 SM | 500 ft | 1,000 ft | 2,000 ft |
| Class G, above 1,200 ft AGL and at or above 10,000 ft MSL | Day / Night | 5 SM | 1,000 ft | 1,000 ft | 1 SM |
The Class G nighttime exception in § 91.155(b)(2) is explained below. It does not replace the general nighttime table entry.
Operational context
The table is only the first gate.
These provisions determine how the table applies around surface areas, airports, and airspace boundaries.
Controlled surface area ceiling
Except under § 91.157, VFR flight beneath the ceiling is not allowed within the lateral boundaries of controlled airspace designated to the surface for an airport when the ceiling is less than 1,000 feet.
Takeoff, landing, and traffic patterns
Within Class B, C, D, or E airspace designated to the surface for an airport, the reported ground visibility must be at least 3 SM. If ground visibility is not reported, flight visibility must be at least 3 SM.
Narrow Class G nighttime exception
An airplane in Class G at 1,200 feet AGL or less may operate at night with visibility below 3 SM, but not below 1 SM, only when clear of clouds, in the airport traffic pattern, and within one-half mile of the runway.
At the Class E base
At an altitude that is the base of a Class E layer, the aircraft is considered to be in the airspace directly below that boundary for purposes of the table.
Primary source: 14 CFR § 91.155
Educational use only. Verify the current regulation, airspace, weather, and all applicable operating requirements before flight. This guide is not a substitute for the regulation or an official preflight briefing.