FAR Ninety-One Point One Fifty-Five, the VFR Weather Minimums Table, and the Six Airspace Classes Every Cross-Country Student Has to Know Cold Before Checkride Day

FAR 91.155 governs the minimum visibility and cloud clearance required for VFR flight in U.S. airspace. Requirements vary by airspace class and altitude, with two concepts applying throughout: visibility (how far you can see in a straight line) and cloud clearance (how far you must stay from clouds above, below, and horizontally). The higher the altitude and the more controlled the airspace, the stricter the requirements.

Why Do VFR Weather Minimums Exist?

The regulatory philosophy behind FAR 91.155 is see-and-avoid. You need enough time and space to spot other aircraft and act before a conflict. Cloud clearance has three dimensions - above, below, and horizontal - because a cloud can hide traffic from any direction.

Class A: No VFR Permitted

Class A airspace begins at 18,000 feet MSL and extends upward. VFR flight is not authorized in Class A. It is IFR-only airspace, so there are no VFR weather minimums to apply there.

What Are the VFR Minimums in Class B Airspace?

Class B surrounds the busiest airports in the country - Atlanta, Chicago, Los Angeles, Dallas - shown as concentric blue rings on your sectional. An ATC clearance is required every time you enter.

The minimums in Class B: 3 statute miles visibility and clear of clouds.

There is no specific above/below/horizontal cloud clearance distance in Class B. ATC has radar coverage of all traffic and provides sequencing and separation services, which partly shares the see-and-avoid burden with the controller. You still cannot be inside a cloud, and you still need 3 miles of visibility.

What Are the VFR Minimums in Class C and Class D Airspace?

Class C and Class D share identical weather minimums - memorize them together.

Class C surrounds airports with an operating approach control and radar service. Class D surrounds airports with a control tower but no approach control.

Both require: 3 statute miles visibility, 1,000 feet above clouds, 500 feet below clouds, and 2,000 feet horizontal from clouds.

The memory device almost every instructor uses: 1-5-2. One thousand above. Five hundred below. Two thousand horizontal. That same 1-5-2 cloud clearance applies to Class C, Class D, and Class E below 10,000 feet MSL - the majority of controlled airspace most VFR pilots ever operate in.

Three miles. 1-5-2. That combination covers the core requirement for most cross-country flying.

What Are the VFR Minimums in Class E Airspace?

Class E doesn’t look the same everywhere on the sectional, which is where confusion starts.

Class E can begin at the surface (dashed magenta), at 700 feet AGL (the graduated magenta boundary in transition areas), at 1,200 feet AGL (the default floor of controlled airspace in many areas), or at 10,000 feet MSL across the entire continental U.S.

For Class E below 10,000 feet MSL, the minimums match Class C and D: 3 statute miles visibility, 1-5-2 cloud clearance.

At or above 10,000 feet MSL, requirements increase: 5 statute miles visibility, with 1,000 feet above, 1,000 feet below, and 1 statute mile horizontal.

A parallel memory device for the above-10,000 standard: 1-1-1. One thousand above, one thousand below, one mile horizontal.

The reason for the increase: closure speeds. Aircraft move faster at altitude, which shortens your reaction time if another aircraft emerges from a cloud. The regulation builds in more margin because the physics demand it.

What Are the VFR Minimums in Class G Airspace?

Class G is uncontrolled airspace - no ATC radar coverage, no communication required. It typically exists below the floor of Class E, often from the surface up to 1,200 feet AGL in rural areas.

Class G minimums depend on both altitude and time of day.

Class G at or below 1,200 feet AGL - daytime: 1 statute mile visibility, clear of clouds

Class G at or below 1,200 feet AGL - nighttime: 3 statute miles visibility, 1-5-2 cloud clearance

Class G above 1,200 feet AGL but below 10,000 feet MSL - daytime: 1 statute mile visibility, 1-1-1 cloud clearance

Class G above 1,200 feet AGL but below 10,000 feet MSL - nighttime: 3 statute miles visibility, 1-5-2 cloud clearance

Class G at or above 10,000 feet MSL: 5 statute miles visibility, 1-1-1 cloud clearance

The day/night difference in the lower altitude bands exists because your visual picture degrades significantly at night. You might spot another aircraft’s position light but miss the cloud it just emerged from until you are inside it.

A Mental Framework for the Whole Table

Two anchor points make the full table easier to hold in memory.

The most demanding VFR standard: at or above 10,000 feet MSL - 5 miles, 1-1-1. Maximum altitude, maximum speed, maximum buffer.

The most permissive standard: Class G below 1,200 feet AGL during the day - 1 mile, clear of clouds. That is the legal floor.

Everything else in the table falls between those two poles.

Legal Minimums vs. Actual Safety Margins

The minimum is not the standard. That distinction matters most in Class G below 1,200 feet AGL during the day, where legal minimums are at their lowest and no external safety infrastructure exists.

Picture two aircraft - both VFR-legal, both at 1 statute mile visibility in uncontrolled airspace below 1,200 feet AGL, one departing a small strip the other pilot didn’t know was there. Head-on. Two Cessna 172s at a combined closure speed of roughly 120 knots. At 1 statute mile of separation, you have approximately 15 seconds from first visual contact to recognize the situation, decide on a course of action, and execute the turn.

That assumes you see each other immediately. In haze, at that distance, you might not.

The regulation keeps you legal. The margin keeps you safe. Those are two different numbers, and the legal minimum is never the target.

What Is Special VFR and When Can You Use It?

Special VFR (SVFR) is an ATC authorization that permits operations within Class B, C, D, or E surface areas with less than standard VFR minimums. The Special VFR minimums are 1 statute mile visibility and clear of clouds - not 1-5-2. You cannot be inside a cloud, but proximity to clouds is permitted.

Key points:

• Special VFR is a request, not a right. ATC can approve or deny based on traffic.
• At night, Special VFR requires an instrument rating and an instrument-equipped aircraft. A VFR-only private pilot cannot use Special VFR after dark.
• At certain high-traffic airports, Special VFR is prohibited entirely, listed as “No SVFR” in the Chart Supplement. This typically applies to Class B airports where IFR traffic volume makes SVFR operations unworkable.

How Examiners Test FAR 91.155 on the Checkride

The Airman Certification Standards require demonstrated understanding, not recitation. An examiner is unlikely to ask “what’s the visibility requirement in Class Delta?” - anyone who studied for an hour can answer that.

The more likely format is a scenario: your cross-country route crosses a Class E surface extension near a non-towered airport with an instrument approach, then continues over open country. The answer starts with the sectional. Dashed magenta on the chart indicates a Class E surface area even without a control tower. No tower does not mean uncontrolled. The chart defines the airspace class, and the airspace class determines the minimums.

Identify the airspace for each phase of the flight. Apply the correct minimums to each segment. Compare against your weather briefing.

How to Apply This on an Actual Cross-Country

Build your pre-flight weather picture from multiple sources:

• METARs - current conditions at reporting stations
• TAFs - forecast conditions at departure and destination
• PIREPs - actual in-flight conditions from pilots on or near your route
• AIRMETs - broader hazard areas between reporting stations

The question you’re asking against all that data: does the reported and forecast visibility and ceiling meet the minimums for each airspace class along my route? Legal and safe are separate evaluations. The legal question comes from FAR 91.155. The safety question requires honest judgment about margins, personal limits, and where the weather is going - not just where it sits right now.

Know your legal minimum. Know your personal minimum. They are two different numbers.

Key Takeaways

• FAR 91.155 sets VFR weather minimums by airspace class; Class A is IFR-only with no VFR minimums because VFR is not permitted.
• Class B requires 3 miles visibility and clear of clouds; Class C and D require 3 miles and 1-5-2 cloud clearance; Class E below 10,000 MSL matches C and D.
• Above 10,000 feet MSL in both Class E and Class G, the standard jumps to 5 miles and 1-1-1 (1,000 above, 1,000 below, 1 mile horizontal).
• Class G below 1,200 AGL in daytime is the most permissive standard - 1 mile visibility, clear of clouds - and the environment with the least outside safety structure.
• Special VFR is a request, not a right; it is unavailable to VFR-only pilots at night and prohibited at certain high-traffic airports marked “No SVFR” in the Chart Supplement.