CAVU

CAVU stands for Ceiling And Visibility Unrestricted. It describes a set of atmospheric conditions where the cloud ceiling is at least 10,000 feet above ground level and horizontal visibility extends at least 10 miles in all directions. Under these conditions, a pilot operating under visual flight rules (VFR) has excellent sight lines to the horizon, landmarks, and other aircraft, making navigation and collision avoidance straightforward.

The 10,000-foot and 10-mile thresholds are not arbitrary. The VFR minimum ceiling is typically 3,000 feet; CAVU is well above that floor. Similarly, VFR visibility minimums are 3 miles; CAVU offers more than triple that distance. When conditions meet or exceed these higher values, weather and atmospheric restrictions essentially cease to be operational constraints, and the flight profile is limited mainly by aircraft performance and pilot judgment rather than regulatory minimums.

Aviation maintenance personnel encounter CAVU language primarily in flight logbooks, maintenance work orders, and accident or incident reports. A mechanic may note that a test flight was conducted "in CAVU conditions" to establish that an aircraft performed as expected without atmospheric interference. Conversely, an engine failure or avionics malfunction discovered during a cloudy flight might be harder to diagnose because the pilot had reduced visual reference; documentation of actual weather conditions at the time of the event is crucial for troubleshooting.

CAVU is the opposite end of the spectrum from IFR (instrument flight rules) weather, where ceilings drop below 1,000 feet and visibility falls below three miles. Between CAVU and IFR conditions sits a range of marginal VFR and instrument meteorological conditions (IMC) that demand progressively more caution. A mechanic preparing an aircraft for a scheduled flight needs to know what weather category the mission falls into, because that determines whether de-ice systems, anti-icing equipment, or supplemental oxygen systems must be checked and certified.

The term originated in military aviation and entered civilian use through pilot training and air traffic control communication. Its purpose is efficiency: rather than reciting "ceiling is fifteen thousand, visibility is twelve miles" repeatedly, pilots and controllers use the single shorthand CAVU to confirm that flying conditions are unrestricted. The acronym is now standard in flight planning, briefings, and maintenance documentation across general and commercial aviation.