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The height above the ground or water of the base of the lowest layer of cloud below 6000 meters (20,000 feet) covering more than half the sky. [2] United Kingdom The vertical distance from the elevation of an aerodrome to the lowest part of any cloud visible from the aerodrome which is sufficient to obscure more than half of the sky. [3] United ...
[1] In some countries pilots are required to get an air traffic control (ATC) clearance, or in absence of a controller, advise the nearest flight service station or center. Pilots are required to adhere to VFR minima when climbing and descending over the clouds. Flight in cloud is not permitted. [1]
VFR / VMC visibility requirements in the US. In aviation, visual meteorological conditions (VMC) is an aviation flight category in which visual flight rules (VFR) flight is permitted—that is, conditions in which pilots have sufficient visibility to fly the aircraft maintaining visual separation from terrain and other aircraft.
Although relatively straightforward to measure (visually, for instance, by using a mirror [3]), oktas only estimate cloud cover in terms of the area of the sky covered by clouds. They do not account for cloud type or thickness, and this limits their use for estimating cloud albedo or surface solar radiation receipt.
Broken, low to mid-level clouds. A broken sky has thin strips of clear blue peeking through abundant clouds. Broken clouds don’t form a uniform layer across the sky; they can be thinner in spots ...
Under visual meteorological conditions, the minimum visual range, distance from clouds, or cloud clearance requirements to be maintained above ground vary by jurisdiction, and may also vary according to the airspace in which the aircraft is operating. [4] In some countries, VFR flight is permitted at night, and is known as night VFR.
Thus, cloud ceiling and flight visibility are the most important variables for safe operations during all phases of flight. [3] The minimum weather conditions for ceiling and visibility for VFR flights are defined in FAR Part 91.155, and vary depending on the type of airspace in which the aircraft is operating, and on whether the flight is ...
ii. Broken down into geographical areas, and/or states; iii. Describes cloud and weather affecting VFR flight operations, including precipitation, thunderstorms, and sustained surface winds 20 Kts or greater. Also includes visibility when the forecast to visibility is between 3 and 6 SM and/or obstructions to visibility