Definition
In a METAR, BKN is a sky cover contraction reporting that 5/8 to 7/8 of the sky at a given layer is covered by clouds. It is reported with the height of the cloud base in hundreds of feet above ground level (for example, BKN025 means a broken layer at 2,500 feet AGL). A BKN layer is considered a ceiling.
Plain English
BKN means most of the sky at that level is covered by cloud, but not quite all of it. The number after BKN tells you how high the bottom of that cloud layer is, in hundreds of feet above the ground.
Context Anchor
Seen in METAR weather reports and other aviation weather products when cloud coverage is listed, such as “BKN025.”
Derivation
“Broken” describes a cloud layer that is mostly continuous but has gaps — like something whole that has been broken into pieces with spaces between them. That everyday image matches what the pilot sees: cloud cover with breaks in it.
Why Pilots Care
A broken layer counts as a ceiling under FAA rules. Ceilings drive VFR/IFR flight category decisions, alternate airport requirements, and approach minimums, so spotting BKN in a METAR directly affects whether and how the flight can be flown.
Analogy
Think of dividing the sky into eight equal parts. BKN means five, six, or seven of those parts are covered by clouds.
Intuition Check
“Broken” does not mean a few separate clouds here. In aviation weather, it specifically means 5/8 to 7/8 of the sky is covered at that layer.
Example Sentence 1
The METAR reported BKN040, so we briefed the approach expecting a ceiling at 4,000 feet.
Example Sentence 2
With BKN conditions reported, the pilot prepared for possible instrument approaches.