CAVOK in aviation means Ceiling and Visibility OK—and what pilots should know

What do the letters "CAVOK" signify in an aviation context?

• A. Clouds and Visibility OK
• B. Ceiling and Visibility OK
• C. Clear Air Visibility OK
• D. Current Altimeter and Visibility OK

Answer: (B)

In aviation, the term "CAVOK" stands for "Ceiling and Visibility OK." This phrase is used in meteorological reports and signifies that the weather conditions are suitable for flying, with no significant weather phenomena or obstructions present. Specifically, it means that visibility is 10 kilometers or greater, and there are no significant clouds below 5,000 feet or below the highest minimum sector altitude. Additionally, no significant weather events, such as rain, snow, or thunderstorms, are occurring in the area. This term is especially important in the context of aviation safety and operations, as pilots rely on these conditions to make informed decisions regarding their flights. The clear communication of weather conditions through standardized terminology like "CAVOK" helps ensure a common understanding among pilots, air traffic control, and meteorological services. The other options contain elements that are not used in the official definition of "CAVOK." For example, while clouds and visibility are indeed part of the aviation weather context, the specific phrase "CAVOK" correctly relates to ceilings, making the correct choice definitive in this case.

If you’ve ever scanned a METAR late at night and spotted a single line at the end that says CAVOK, you might have felt a twinge of curiosity. What does that puzzling three-letter word actually mean in the real world of flying? Here’s the quick, no-nonsense version: CAVOK stands for Ceiling and Visibility OK. In other words, the weather looks good enough for normal flying, with enough visibility and cloud ceiling to keep things straightforward.

Let’s unpack what that means in practical terms and why it matters beyond just memorizing an acronym.

What does CAVOK actually signify?

CAVOK is a shorthand used in aviation weather reporting to signal three core conditions are favorable:

• Ceiling: There are no significant clouds below 5,000 feet (or below the highest minimum sector altitude) in the area. In plain English, there isn’t a low cloud layer that would suddenly close you in if you’re flying at low levels. Clouds might be up higher, but there’s no low fog or rain cloud hanging over every field.

• Visibility: The visibility is 10 kilometers or more. That’s about 6.2 miles, give or take, depending on the region. In practice, you can see far enough to spot other traffic, ground features, and landmarks without strain.

• No significant weather: There are no notable weather phenomena like rain, snow, thunderstorms, snow showers, or blowing dust that would hamper flight operations. It’s the “clear skies and calm winds” vibe, at least for the moment.

A practical mental model: imagine you’re planning a short hop in a small, light aircraft. If the METAR puts CAVOK in the forecast chunk, you’re looking at a day when you can stay comfortably in VFR territory—good visibility, no looming weather hazards, and clouds that aren’t sneaking into your flight path.

How CAVOK appears in real-life weather reports

In the aviation weather world, METARs (weather observations) and TAFs (forecast weather) are the go-to sources. CAVOK is most often encountered at the end of a METAR observation when conditions meet the criteria we just spelled out. It’s a compact way of saying, “All of the above are in good shape.”

A quick, representative example (simplified for clarity) might look like this:

METAR KJFK 151753Z 27012KT 9999 FEW060 SCT090 24/15 A2992 CAVOK

Here’s what that means, in plain terms:

• 9999 means visibility is 10 kilometers or more.

• FEW060 and SCT090 indicate some cloud layers, but both are above 5,000 feet, so they don’t violate the “no low ceilings” rule for CAVOK.

• The “CAVOK” tag at the end confirms all three conditions are in a favorable state for standard flight operations.

The important takeaway is this: CAVOK doesn’t mean “perfect weather everywhere.” It means, at the observation point, the ceiling is high enough, visibility is good, and there aren’t significant weather phenomena to worry about. It’s a signal to pilots that, for the moment, the weather supports straightforward flight planning and execution.

What CAVOK implies for pilots and operations

• Simpler planning: When CAVOK is in effect, flight planning can be more straightforward. You’re not juggling low ceilings or patchy precipitation, which often means less need for complex routing or contingency planning.

• Safer hands-on flying: For VFR pilots, good visibility and higher ceilings translate into clearer horizon reference, easier scanning for traffic, and a comfortable margin to maneuver.

• Expectations for ATC and logistics: Clear weather signals smoother coordination with air traffic control because there are fewer weather-driven deviations or holds to manage.

But a quick caveat: the CAVOK signal is weather-specific. It doesn’t guarantee that every part of the sky around you is perfectly clear or that you won’t encounter turbulence, wind shear, or microbursts elsewhere. Weather can be patchy. A field near you could be CAVOK while another nearby airstrip experiences a different picture. That’s why pilots still perform a thorough risk assessment and check alternate routes or airports when needed.

Common questions and clarifications

• Is CAVOK the same as “clear skies”? Not exactly. It means ceiling and visibility are OK, and there are no significant weather phenomena. There might still be some clouds, but they’re not low enough to interfere with standard flight at the moment.

• Can there be clouds above 5,000 feet and still have CAVOK? Yes. Clouds above the 5,000-foot level are allowed under CAVOK, as long as there are no significant weather events and no low ceilings that would affect the intended flight path.

• Does CAVOK mean I should forget about weather checks? Not at all. You still need to review the full METAR and TAF, along with other advisories. CAVOK is a piece of the weather puzzle, not the entire picture.

Related terms you’ll encounter

• METAR and TAF: The two most common weather products in aviation. METAR is the current observation; TAF is the forecast for the next 24 to 30 hours. CAVOK is a tidy sign you’ll sometimes see in METARs.

• Cloud bases and ceiling categories: Clouds are reported in terms of base height and coverage (FEW, SCT, BKN, OVC). CAVOK implies that any significant cloud below 5,000 feet isn’t present.

• Visibility codes: While CAVOK points to visibility of 10 km or more, you’ll also see numbers like 6SM (statute miles) depending on the region. The key idea is “high visibility,” but the exact unit changes with location.

• Other shorthand you might see: SKC (sky clear), FEW, SCT, BKN, OVC, and RVR (runway visual range) are all part of the weather briefing language you’ll hear in pilots’ world.

A few tips to remember when you’re reading reports

• Look for the CAVOK tag at the end of the METAR. If it’s there, you’ve got a concise summary of favorable ceiling and visibility with no significant weather.

• Check the ceiling separately if you’re operating at a nonstandard altitude. The phrase “no significant clouds below 5,000 feet” is part of CAVOK, but you’ll still want to know what lies above that threshold for planning at higher altitudes.

• Cross-reference with nearby stations. Weather isn’t stationary; what’s true at one field might differ a few miles away, especially in active weather regimes.

A quick way to connect it to the bigger picture

Weather is a living thing in aviation. CAVOK is one of those crisp, memorable terms that help pilots communicate quickly and safely. It’s like the cockpit equivalent of checking the gas gauge and the fuel clear switch before you roll onto the runway. When the conditions meet CAVOK, you’ve got a solid baseline to fly by—no drama, no guesswork, just dependable visibility and an adequate ceiling, with the weather’s less friendly aspects tucked safely away for the moment.

What to keep in mind as you expand your weather literacy

• Context matters: CAVOK is a snapshot. The broader forecast and other weather reports matter for planning multiple legs or longer trips.

• Regional variations exist: Units and reporting conventions differ by region. In some places, visibility is given in kilometers, in others in miles. Clouds are described with different measurement cues in different countries. The core idea, though, is universal: good ceiling, good visibility, no significant weather.

• Practice, not memorization alone: Real-world familiarity comes from reading a lot of METARs, listening to briefings, and seeing how reports translate into decisions in the cockpit. The more you see, the more intuitive it becomes.

A final thought

CAVOK isn’t just a clever acronym. It’s a practical signal that, in the moment, the weather is favorable enough to keep operations smooth and predictable. It’s that reassurance pilots crave when they’re about to take off, when they’re scanning the skies for signs of trouble, and when they’re plotting a route with a coffee cup in hand. So next time you spot CAVOK in a report, you’ll recognize it not as a mysterious string of letters, but as a concise weather brief—one that tells you the ceiling is high, the visibility is clear, and the weather has, for now, given you the green light to go.

If you’re curious, keep exploring METARs and their shorthand. The more you read, the more second nature it becomes, and the more confident you’ll feel when the sky is the only thing between you and your destination.