What defines a ceiling in aviation?

Definition. The height above the ground or water of the base of the lowest layer of cloud below 6 000 metres (20 000 feet) covering more than half the sky. ( ICAO Annex 2)

What’s considered a ceiling?

The height above the Earth’s surface of the lowest layer of clouds or obscuring phenomena that is reported as broken, overcast, or obscuration, and not classified as thin or partial.

What cloud coverage constitutes a ceiling?

For aviation, the altitude of cloud base for the lowest cloud with coverage ≥ 5 oktas (i.e. lowest broken or overcast clouds) is considered the ceiling (see Learning Goal 1d). Sometimes the sky is obscured, meaning that there might be clouds but the observer on the ground cannot see them (see Learning Goal 1i).

Is Fog considered a ceiling?

After all, both conditions are technically identical: ceiling is a cloud, while reduced visibility is often caused by fog, which is simply a cloud on the ground. When the ceiling drops below 3000 feet, the visibility often diminishes. Likewise when fog sets in, a low ceiling often follows.

What is a low ceiling in aviation?

In weather and aviation it means low hanging fairly continuous clouds. Like the ceiling of a room. Anything below about 1000 ft AGL could qualify as a low ceiling.

Is few considered a ceiling?

Cloud cover and measurement of ceiling Cloud cover is reported in terms of 1/8th of sky cover with 1-2/8th being FEW, 3-4/8ths being SCT, 5-7/8th being BKN and 8/8 denoted at OVC. We find that these weather observers are generally the most reliable source in determining accurate ceilings.

Are ceilings MSL or AGL?

Area Forecasts (FA) are always MSL unless the height is specifically tagged AGL or CIG (for “ceiling”). It may seem annoying that FA’s are MSL, but they cover large areas where the terrain may vary but the clould bases are usually at a constant height MSL. That is generally more useful for enroute flight planning.