Regulations Reference
Use the VFR / IFR Minimums Checker below to instantly check whether your ceiling and visibility meet the legal requirements for Visual Flight Rules (VFR) or Instrument Flight Rules (IFR) flight. The checker covers FAA 14 CFR 91.155, ICAO Annex 2, and UK CAA standards across all airspace classes from Class A to Class G, and includes flight category identification, Special VFR (SVFR) eligibility, instrument approach category limits, and IFR alternate minimums.
Usage Guide
Follow the steps below to use the VFR / IFR Minimums Checker to check your ceiling and visibility against legal minimums across all airspace classes.
Enter your cloud ceiling in feet AGL — use the lowest broken (BKN) or overcast (OVC) layer from the METAR. Few (FEW) and scattered (SCT) layers do not count as ceiling. Enter visibility in the field next to it and select the unit from the dropdown: statute miles (SM), kilometres (km), or metres (m). The checker converts your input to statute miles automatically for the minimums comparison.
Toggle Day or Night — night minimums are stricter in Class G airspace. Select your regulatory standard from the dropdown: FAA (14 CFR Part 91), ICAO (Annex 2), or UK CAA. Then select your altitude band: below 1,200 ft AGL, 1,200–10,000 ft AGL, or at or above 10,000 ft MSL. Different altitude bands apply different VFR minimums, particularly in Class G airspace.
The flight category banner updates instantly — VFR (green), MVFR (blue), IFR (red), or LIFR (magenta) — based on the most restrictive of your entered ceiling and visibility values. The banner also shows the specific weather factor that determined the category.
Below the flight category banner, the airspace grid shows a pass or fail result for each airspace class under the selected regulatory standard. The Special VFR (SVFR) box shows whether SVFR conditions are met. The Instrument Approach Categories panel shows which IFR approach types — from non-precision to CAT IIIb — are available for the entered conditions.
VFR Defined
A VFR weather minimum is the minimum visibility and cloud clearance required for a pilot to operate an aircraft under Visual Flight Rules (VFR).
VFR weather minimums ensure that pilots can maintain visual reference to the ground, avoid clouds, and see other aircraft in sufficient time to prevent collisions. These minimums vary according to the airspace class, altitude, and whether the flight is conducted during the day or at night.
Aviation authorities publish VFR weather minimums in national flight regulations. In the United States, the Federal Aviation Administration (FAA) publishes these requirements in 14 CFR §91.155. Other countries publish equivalent requirements through their own civil aviation authorities or in accordance with ICAO standards.
A pilot must satisfy the applicable VFR weather minimums before operating under VFR. If weather conditions fall below these minimums, the flight must either operate under Instrument Flight Rules (IFR), obtain Special VFR (SVFR) clearance where permitted, or remain on the ground until conditions improve.
IFR Defined
An IFR weather minimum is the minimum weather condition required to safely conduct a flight or instrument approach under Instrument Flight Rules (IFR).
Unlike Visual Flight Rules (VFR), Instrument Flight Rules (IFR) operations do not require pilots to maintain visual reference to the ground during en-route flight. Instead, pilots navigate primarily by reference to flight instruments while operating under Air Traffic Control (ATC) clearance. However, IFR weather minimums still define the lowest visibility and cloud conditions that permit specific phases of flight, particularly instrument approaches and landings.
IFR weather minimums vary according to the type of instrument approach procedure, the airport equipment, aircraft performance, and obstacle environment. They are published on instrument approach charts and typically specify a Decision Altitude (DA) or Minimum Descent Altitude (MDA) together with the required flight visibility or Runway Visual Range (RVR).
A pilot may begin an IFR flight in weather below VFR minimums if the flight meets all applicable IFR requirements. However, an instrument approach may only continue below the published DA or MDA when the required visual references for landing are visible and the reported weather meets the published approach minimums. If these conditions are not met, the pilot must execute the published missed approach procedure.
METAR Reading
A METAR provides the weather information needed to determine whether current conditions meet VFR or IFR weather minimums.
When checking minimums, pilots should focus on four key elements of the METAR: visibility, cloud layers, ceiling, and weather phenomena. Visibility indicates how far a pilot can see horizontally and is reported in statute miles or metres, depending on the country. Cloud layers identify cloud coverage and base altitude, while the ceiling is the height of the lowest broken (BKN) or overcast (OVC) cloud layer. Weather phenomena such as fog (FG), mist (BR), rain (RA), or snow (SN) can further reduce visibility and affect flight conditions.
Pilots compare the reported visibility and ceiling with the applicable weather minimums for the planned airspace class, flight rules, and instrument approach, if applicable. For VFR flights, the reported visibility and cloud clearance must satisfy the published VFR weather minimums. For IFR operations, pilots compare the reported weather with the published approach minimums, including the required flight visibility or Runway Visual Range (RVR).
A METAR describes observed weather at the airport at the time of observation. Pilots should also review the latest Terminal Aerodrome Forecast (TAF) and other weather information to evaluate expected conditions during the entire flight.
Flight Categories
VFR, MVFR, IFR, and LIFR are weather flight categories that summarize current or forecast flying conditions based on visibility and ceiling.
These categories help pilots quickly assess whether weather conditions are generally suitable for Visual Flight Rules (VFR) or Instrument Flight Rules (IFR) operations. They appear on many aviation weather products, including airport weather maps and flight planning tools. The categories provide a rapid overview, but they do not replace the published weather minimums that apply to a specific flight.
The table below compares the standard VFR, MVFR, IFR, and LIFR flight categories using their published ceiling and visibility criteria.
A flight category is determined by the most restrictive value between ceiling and visibility. For example, a METAR reporting 10 statute miles of visibility but a 700-foot ceiling is classified as IFR because the ceiling falls within the IFR range.
Flight categories are advisory tools for weather interpretation. A pilot must always compare the actual METAR, Terminal Aerodrome Forecast (TAF), and published VFR or IFR weather minimums with the planned operation before deciding whether a flight is legal and safe.
FAA Regulations
FAA VFR weather minimums define the legal minimum visibility and cloud clearance required for Visual Flight Rules operations under 14 CFR §91.155. These values represent regulatory compliance limits and do not include operational safety margins, so pilots should plan above these minimum thresholds whenever possible.
The table below shows the required flight visibility and cloud clearance distances for each airspace class and altitude band under FAA regulations.
Source: 14 CFR §91.155 (FAA). Regulatory compliance required; always verify current amendments before flight.
ICAO & UK CAA
ICAO VFR weather minimums define the international baseline for flight visibility and cloud clearance under Visual Flight Rules (VFR). Most countries follow ICAO Annex 2, while individual aviation authorities may publish national differences. In the United Kingdom, the UK Civil Aviation Authority (CAA) publishes these differences in the UK AIP ENR 1.2.
The table below summarizes the standard ICAO VFR weather minimums used by many ICAO member states.
Source: ICAO Annex 2, Table 3-1. Individual countries publish national differences in their Aeronautical Information Publication (AIP).
The UK Civil Aviation Authority (CAA) generally follows ICAO Annex 2, but publishes additional operating requirements and national differences in the UK AIP ENR 1.2.
No VFR flight is permitted in UK Class A airspace. Airways in the United Kingdom are generally Class A, so VFR pilots must remain outside these airways unless an appropriate clearance is obtained.
Controlled airspace requires 5 km flight visibility, 1,500 m horizontal cloud clearance, 1,000 ft above clouds, and 1,000 ft below clouds. Below 3,000 ft AMSL or 1,000 ft AGL, whichever is higher, aircraft may instead operate clear of cloud and in sight of the surface, provided the required visibility is maintained.
Above 3,000 ft AMSL or 1,000 ft AGL, standard ICAO cloud clearance and visibility requirements apply. At or below these heights, pilots may operate clear of cloud and in sight of the surface while maintaining the required flight visibility.
Pilots must obtain Special VFR (SVFR) clearance from Air Traffic Control (ATC) before operating under SVFR. The aircraft must remain clear of cloud, in sight of the surface, and maintain at least 1,500 m flight visibility during the day or 3 km at night. SVFR is available only in designated controlled airspace and should always be verified in the relevant aerodrome AIP.
The UK low-flying rule normally requires aircraft to remain at least 500 ft from any person, vehicle, vessel, or structure, except during take-off and landing. Helicopters may operate below this height when doing so does not create a hazard.
Airspace Classes
VFR weather minimums vary by airspace class because each class provides a different level of air traffic control and aircraft separation.
Airspace classes determine the minimum flight visibility and cloud clearance required for legal Visual Flight Rules (VFR) operations. Controlled airspace generally requires greater separation from clouds because aircraft operating under Instrument Flight Rules (IFR) may be present. Uncontrolled airspace often permits lower weather minimums, especially at lower altitudes where aircraft operate at slower speeds.
The following airspace classes use different VFR weather minimums to account for differences in aircraft separation, traffic density, and Air Traffic Control (ATC) services.
Pilots must always identify the airspace class before comparing the reported METAR conditions with the applicable VFR weather minimums. Flying with sufficient visibility in the wrong airspace does not guarantee legal VFR operation if the required cloud clearance or visibility minimum is not met.
Special VFR
Special VFR (SVFR) allows a pilot to operate under Visual Flight Rules (VFR) within certain controlled airspace when the weather is below standard VFR minimums but still suitable for safe visual flight.
An Air Traffic Control (ATC) clearance is required before a pilot may operate under SVFR. Pilots cannot enter or remain in controlled airspace under SVFR without receiving this clearance. SVFR is normally available only within designated control zones (CTRs) or other specified controlled airspace and is subject to local procedures.
To operate under SVFR, the aircraft must remain clear of clouds and in sight of the surface at all times. The required minimum flight visibility depends on the country and applicable regulations. For example, the FAA generally requires at least 1 statute mile of flight visibility for airplanes, while many ICAO member states require 1,500 metres or more. Additional restrictions may apply to night operations and pilot qualifications.
SVFR provides flexibility when weather temporarily falls below standard VFR minimums, but it is not intended to replace Instrument Flight Rules (IFR). Pilots should request SVFR only when they can safely maintain visual reference throughout the operation and comply with all published regulatory requirements.
IFR Minimums
IFR weather minimums define the minimum ceiling and visibility required to conduct an instrument approach or landing under Instrument Flight Rules (IFR).
Unlike Visual Flight Rules (VFR), IFR does not require a minimum ceiling or visibility for the en-route portion of a flight. A pilot may fly in clouds or below VFR weather minimums while operating under an Air Traffic Control (ATC) clearance. However, weather minimums become critical during an instrument approach because the pilot must safely transition from instrument references to visual references before landing.
The required ceiling and visibility depend on the published instrument approach procedure rather than on the airspace class. Every approach chart specifies a Decision Altitude (DA) or Decision Height (DH) for precision approaches, or a Minimum Descent Altitude (MDA) for non-precision approaches, together with the required flight visibility or Runway Visual Range (RVR). Lower approach minimums are generally available at airports equipped with more advanced navigation and landing systems, such as an Instrument Landing System (ILS).
A pilot may descend below the published DA, DH, or MDA only when the required visual references for the intended runway are visible and all applicable regulatory requirements are satisfied. If these conditions are not met at the required altitude, the pilot must immediately execute the published missed approach procedure.
Approach Categories
Instrument approach categories define the minimum decision altitude, visibility, and guidance capability required to conduct a safe IFR landing.
IFR approach minimums are published per instrument approach procedure and depend on the level of navigation precision, aircraft equipment, and airport certification. These categories determine how low a pilot may descend before requiring visual contact with the runway environment under Instrument Flight Rules (IFR).
The table below summarizes the main IFR approach categories used in modern aviation, from basic non-precision approaches to advanced autoland systems.
IFR approach categories define how much visual confirmation is required before landing and how much onboard or ground-based guidance is available. Lower category approaches require more advanced aircraft systems, stricter pilot qualification, and higher levels of airport infrastructure certification.
A pilot must always use the published minimums on the actual approach plate, not generic category values, because approach minima vary by runway, equipment status, and aircraft certification.
1-2-3 Rule
The 1-2-3 rule for IFR alternate planning determines when a pilot must file an alternate airport based on forecast weather conditions at the destination.
The Federal Aviation Administration (FAA) uses the 1-2-3 rule in 14 CFR §91.169 to define when an Instrument Flight Rules (IFR) flight plan requires an alternate airport. This rule evaluates the forecast conditions at the destination airport at the expected time of arrival using the Terminal Aerodrome Forecast (TAF).
Under the 1-2-3 rule, a pilot must file an alternate airport if the forecast conditions at the destination are below any of the following thresholds: ceiling less than 2,000 feet AGL, visibility less than 3 statute miles, or both conditions occurring within 1 hour before or after the estimated time of arrival.
If the forecast shows a ceiling of 2,000 feet or higher and visibility of 3 statute miles or greater, an alternate airport is not required under FAA planning rules. This simplifies flight planning when stable weather conditions are expected.
An alternate airport must meet specific alternate minimums, which are published in FAA instrument approach procedures or determined using standard regulatory rules when alternate minimums are not listed. Pilots use the 1-2-3 rule to ensure sufficient margin for weather uncertainty during IFR operations.
Alternate Minimums
IFR alternate airport minimums define the minimum weather conditions required at an alternate aerodrome when a pilot files an Instrument Flight Rules (IFR) flight plan.
The Federal Aviation Administration (FAA) and other aviation authorities require pilots to verify that forecast and published instrument approach minimums at the alternate airport are suitable for a safe landing if diversion becomes necessary. These requirements ensure that an alternate airport remains usable if the destination airport becomes unavailable due to weather, traffic, or operational constraints.
In FAA operations, alternate minimums depend on whether the airport has a published instrument approach procedure. If a standard instrument approach is available, the pilot must ensure that forecast weather at the estimated time of arrival meets or exceeds the published decision altitude (DA) or minimum descent altitude (MDA), along with the required flight visibility or Runway Visual Range (RVR), plus any additional regulatory margins specified in FAA alternate minimums rules (14 CFR §91.169).
If no instrument approach procedure is available at the alternate airport, the FAA requires the pilot to ensure that the ceiling and visibility allow a safe descent, approach, and landing under basic visual conditions. In practice, this requires higher weather margins because no precision or non-precision guidance is available.
Many operators use a simplified planning standard known as the 1-2-3 rule for determining when an alternate is required, but alternate minimums themselves define the actual weather thresholds that must be met once an alternate airport is selected. These minimums vary depending on the approach type, airport equipment, and applicable national regulations published in the Aeronautical Information Publication (AIP) or equivalent authority documentation.
Quick Reference
VFR, IFR, and SVFR define three different sets of flight rules that determine how a pilot operates, navigates, and complies with weather and Air Traffic Control (ATC) requirements. These flight rules differ in weather minimums, ATC involvement, and pilot responsibility for separation. The table below provides a quick operational comparison used in flight planning and airspace decision-making.
Pilots must select the appropriate flight rule based on weather conditions, airspace class, and ATC clearance requirements before departure and during flight.
Common Mistakes
Pilots make common VFR and IFR minimums mistakes when they misinterpret airspace rules, weather reports, or instrument approach requirements.
These errors often occur during flight planning, METAR interpretation, and instrument approach selection, where small misunderstandings can lead to regulatory non-compliance or unsafe weather decisions.
A frequent VFR mistake is using general visibility without checking airspace-specific VFR weather minimums. Pilots sometimes assume that 3 statute miles visibility applies everywhere, but Class G airspace allows lower minimums in some conditions, while Class B, C, D, and E airspace require stricter cloud clearance rules.
Another common mistake is misreading METAR reports and confusing reported visibility with required cloud clearance distances. A METAR may show acceptable visibility, but the aircraft may still be below required ceiling or cloud separation minimums for the airspace class.
A common IFR mistake is misunderstanding approach minimums such as Decision Altitude (DA) and Minimum Descent Altitude (MDA). Pilots sometimes descend below minimums without required visual references for the runway environment, which violates IFR procedures and increases terrain risk.
Another IFR error is ignoring alternate airport requirements, especially the FAA 1-2-3 rule (14 CFR §91.169). Pilots may file an IFR flight plan without verifying whether forecast weather requires an alternate airport.
A frequent planning mistake is mixing VFR and IFR concepts, such as applying IFR approach minimums to en-route VFR flight or assuming IFR clearance guarantees safe weather conditions without checking destination minima.
Finally, pilots often underestimate the importance of airspace class identification, leading to incorrect application of VFR or IFR minimums in complex airspace environments.
Common Questions
The ceiling and visibility required for an ILS approach depend on the approach category, ranging from 200 feet and half a statute mile for CAT I to zero ceiling and zero visibility for the theoretical CAT IIIc.
CAT II ILS requires a decision height between 100 and 200 feet and an RVR of at least 1,200 feet. CAT IIIa allows a decision height below 100 feet and an RVR down to 700 feet. CAT IIIb allows RVR down to 150 feet with a decision height below 50 feet.
CAT IIIc is a theoretical zero-zero limit with no decision height and no RVR requirement, but it is not currently certificated for operational use.
Clear of clouds in Class B airspace means the pilot must not fly through or into any cloud formation, but no specified distance above, below, or horizontally from clouds is required.
This differs from other airspace classes where exact cloud clearance distances apply. The clear of clouds requirement in Class B is possible because Air Traffic Control (ATC) provides radar separation between all participating aircraft within the airspace.
Pilots still need to maintain the 3 statute mile visibility minimum and must report deteriorating visibility to ATC.
No — in Class G airspace below 1,200 feet AGL, night VFR requires higher visibility than during the day, not lower. During the day, the FAA allows 1 statute mile visibility and clear of clouds. At night, the minimum increases to 3 statute miles with standard 500-1,000-2,000 cloud clearance.
In controlled airspace (Classes B through E), the same VFR minimums apply during both day and night.
The stricter night requirements in Class G reflect reduced visibility, loss of terrain contrast, and greater difficulty with see-and-avoid separation.
Decision Altitude (DA) applies to precision approaches and is reached while still descending on the glidepath, while Minimum Descent Altitude (MDA) applies to non-precision approaches and requires the pilot to level off and wait for visual contact.
DA is expressed as an altitude above mean sea level (MSL) at which the pilot must decide whether to continue the approach or execute a missed approach.
MDA is the lowest altitude to which the pilot may descend without the required visual references for landing. Unlike DA, the pilot levels off at MDA and waits until visual contact is established or the missed approach point is reached.
A SIGMET does not change published VFR weather minimums, but the conditions it describes — such as severe turbulence, severe icing, volcanic ash, or widespread dust storms — typically make VFR flight impractical or dangerous.
A SIGMET (Significant Meteorological Information) is an advisory issued by a meteorological watch office warning of weather phenomena that may affect aircraft safety.
Pilots planning VFR flights should check for active SIGMETs along their route and treat them as strong indicators that conditions are unsuitable for VFR operations regardless of the reported ceiling and visibility.
Flight visibility is measured from the cockpit by the pilot in flight, while ground visibility is measured by a certified observer or automated system at the airport surface.
Both values may differ because ground-level fog, haze, or precipitation can exist at the surface without affecting visibility at altitude, and vice versa.
FAA regulations use flight visibility as the standard for VFR and IFR minimums compliance during flight, while ground visibility is used to determine whether an instrument approach may be commenced.
A ceiling is the height above ground level of the lowest broken (BKN) or overcast (OVC) cloud layer reported in a METAR.
Broken clouds cover five to seven eighths of the sky and overcast clouds cover more than seven eighths. Few (FEW) and scattered (SCT) cloud layers covering one to four eighths of the sky are not considered ceiling layers for VFR minimums purposes.
In a METAR, cloud layers are reported as a three-letter descriptor followed by a three-digit height in hundreds of feet AGL — for example, BKN015 indicates a broken layer at 1,500 feet AGL, which would be the reported ceiling.
Generally no — a VFR pilot cannot fly above an overcast cloud layer because doing so makes it impossible to maintain the required cloud clearance below the aircraft.
A VFR pilot may fly above a broken or scattered cloud layer only if they can remain in VMC and maintain the required cloud clearance above, below, and horizontally from clouds at all times.
VFR on top is a specific IFR clearance that allows an IFR-rated pilot to fly above a cloud layer under VFR conditions while on an active IFR flight plan, and it is not available to VFR-only pilots.
VFR is a set of flight regulations, while VMC describes the actual weather conditions that meet the minimums required to fly under those rules.
A pilot flying under VFR must be in VMC at all times. If conditions deteriorate below VMC, VFR flight is no longer legal and the pilot must either land, divert, or obtain an IFR clearance.
IMC (Instrument Meteorological Conditions) describes conditions below VMC thresholds, and flight in IMC without an IFR clearance and rating is both illegal and dangerous.
VFR weather minimums increase above 10,000 feet MSL because aircraft at higher altitudes fly faster, which reduces the time available to detect and avoid other traffic.
At higher altitudes, jet aircraft may be cruising at speeds significantly above those of low-altitude traffic, making the standard 3 statute mile visibility and 500-1,000-2,000 cloud clearance insufficient for safe see-and-avoid separation.
The FAA therefore requires 5 statute miles visibility and greater cloud clearance above 10,000 feet MSL to provide adequate reaction time and separation margin at higher airspeeds.